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Preface
The Spring Vault project applies core Spring concepts to the development of solutions using HashiCorp Vault. We provide a "template" as a high-level abstraction for storing and querying documents. You will notice similarities to the REST support in the Spring Framework.
This document is the reference guide for Spring Vault. It explains Vault concepts and semantics and the syntax.
This part of the reference documentation explains the core functionality offered by Spring Vault.
Vault support introduces the Vault module feature set.
1. Document Structure
This section provides basic introduction to Spring and Vault. It contains details about following development and how to get support.
The rest of the document refers to Spring Vault features and assumes the user is familiar with HashiCorp Vault as well as Spring concepts.
2. Knowing Spring
Spring Vault uses Spring framework’s core functionality, such as IoC container. While it is not important to know the Spring APIs, understanding the concepts behind them is. At a minimum, the idea behind IoC should be familiar for whatever IoC container you choose to use.
The core functionality of the Vault support can be used directly, with no need to invoke the IoC services of the Spring Container. This is much like RestTemplate
which can be used 'standalone' without any other services of the Spring container. To leverage all the features of Spring Vault document, such as the session support, you will need to configure some parts of the library using Spring.
To learn more about Spring, you can refer to the comprehensive (and sometimes disarming) documentation that explains in detail the Spring Framework. There are a lot of articles, blog entries and books on the matter - take a look at the Spring framework home page for more information.
3. Knowing Vault
Security and working with secrets is a concern of every developer working with databases, user credentials or API keys. Vault steps in by providing a secure storage combined with access control, revocation, key rolling and auditing. In short: Vault is a service for securely accessing and storing secrets. A secret is anything that you want to tightly control access to, such as API keys, passwords, certificates, and more.
The jumping off ground for learning about Vault is www.vaultproject.io. Here is a list of useful resources:
-
The manual introduces Vault and contains links to getting started guides, reference documentation and tutorials.
-
The online shell provides a convenient way to interact with a Vault instance in combination with the online tutorial.
Spring Vault provides client-side support for accessing, storing and revoking secrets. With HashiCorp’s Vault you have a central place to manage external secret data for applications across all environments. Vault can manage static and dynamic secrets such as application data, username/password for remote applications/resources and provide credentials for external services such as MySQL, PostgreSQL, Apache Cassandra, Consul, AWS and more.
4. Requirements
Spring Vault 2.x binaries requires JDK level 8.0 and above, and Spring Framework 5.3.29 and above.
In terms of Vault, Vault at least 0.6.
5. Additional Help Resources
Learning a new framework is not always straight forward. In this section, we try to provide what we think is an easy to follow guide for starting with Spring Vault module. However, if you encounter issues or you are just looking for advice, feel free to use one of the links below:
5.1. Support
There are a few support options available:
5.1.1. Community Forum
Post questions questions regarding Spring Vault on Stackoverflow to share information and help each other. Note that registration is needed only for posting.
5.1.2. Professional Support
Professional, from-the-source support, with guaranteed response time, is available from Pivotal Sofware, Inc., the company behind Spring Vault and Spring.
5.2. Following Development
For information on the Spring Vault source code repository, nightly builds and snapshot artifacts please see the Spring Vault homepage. You can help make Spring Vault best serve the needs of the Spring community by interacting with developers through the Community on Stackoverflow. If you encounter a bug or want to suggest an improvement, please create a ticket on the Spring Vault issue tracker. To stay up to date with the latest news and announcements in the Spring ecosystem, subscribe to the Spring Community Portal. Lastly, you can follow the Spring blog or the project team on Twitter (SpringCentral).
6. New & Noteworthy
6.1. What’s new in Spring Vault 2.3
-
Support for PEM-encoded certificates for keystore and truststore usage.
-
ReactiveVaultEndpointProvider
for non-blocking lookup ofVaultEndpoint
. -
VaultKeyValueMetadataOperations
for Key-Value metadata interaction. -
Support for
transform
backend (Enterprise Feature). -
Documentation of how to use Vault secret backends.
-
Login credentials for Kubernetes and PCF authentication are reloaded for each login attempt.
-
SecretLeaseContainer
publishesSecretLeaseRotatedEvent
instead ofSecretLeaseExpiredEvent
andSecretLeaseCreatedEvent
on successful secret rotation. -
AbstractVaultConfiguration.threadPoolTaskScheduler()
bean type changed toTaskSchedulerWrapper
instead ofThreadPoolTaskScheduler
. -
Since 2.3.2:
GcpIamCredentialsAuthentication
6.2. What’s new in Spring Vault 2.2
-
Support for Key-Value v2 (versioned backend) secrets through
@VaultPropertySource
. -
SpEL support in
@Secret
. -
Add support for Jetty as reactive HttpClient.
-
LifecycleAwareSessionManager
andReactiveLifecycleAwareSessionManager
emit nowAuthenticationEvent
s. -
Deprecation of
AppIdAuthentication
. UseAppRoleAuthentication
instead as recommended by HashiCorp Vault. -
CubbyholeAuthentication
and wrappedAppRoleAuthentication
now usesys/wrapping/unwrap
endpoints by default. -
Kotlin Coroutines support for
ReactiveVaultOperations
.
6.3. What’s new in Spring Vault 2.1
-
GCP Compute, GCP IAM, and Azure authentication.
-
Template API support for versioned and unversioned Key/Value backends and for Vault wrapping operations.
-
Support full pull mode in reactive AppRole authentication.
-
Improved Exception hierarchy for Vault login failures.
6.4. What’s new in Spring Vault 2.0
-
Authentication steps DSL to compose authentication flows.
-
Reactive Vault client via
ReactiveVaultOperations
. -
Vault repository support based on Spring Data KeyValue.
-
Transit batch encrypt and decrypt support.
-
Policy management for policies stored as JSON.
-
Support CSR signing, certificate revocation and CRL retrieval.
-
RoleId/SecretId unwrapping for AppRole authentication.
-
Spring Security integration with transit backend-based
BytesKeyGenerator
andBytesEncryptor
.
6.5. What’s new in Spring Vault 1.1.0
-
Configuration of encryption/decryption versions for transit keys.
-
Pull mode for AppRole authentication.
-
Transit batch encrypt and decrypt support.
-
TTL-based generic secret rotation.
Reference documentation
7. Vault support
The Vault support contains a wide range of features which are summarized below.
-
Spring configuration support using Java based @Configuration classes
-
VaultTemplate
helper class that increases productivity performing common Vault operations. Includes integrated object mapping between Vault responses and POJOs.
For most tasks, you will find yourself using VaultTemplate
that leverages the
rich communication functionality. VaultTemplate
is the place to look for
accessing functionality such as reading data from Vault or issuing
administrative commands. VaultTemplate
also provides callback methods so that it is easy for you to
get a hold of the low-level API artifacts such as RestTemplate
to communicate
directly with Vault.
7.1. Dependencies
The easiest way to find compatible versions of Spring Vault dependencies is by relying on the Spring Vault BOM we ship with the compatible versions defined.
In a Maven project you would declare this dependency in the
<dependencyManagement />
section of your pom.xml
:
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.vault</groupId>
<artifactId>spring-vault-dependencies</artifactId>
<version>2.3.4</version>
<scope>import</scope>
<type>pom</type>
</dependency>
</dependencies>
</dependencyManagement>
The current version is 2.3.4
.
The version name follows the following patterns: ${version}
for GA and service releases and ${version}-${release}
for snapshots and milestones. release
can be one of the following:
-
SNAPSHOT
- current snapshots -
M1
,M2
etc. - milestones -
RC1
,RC2
etc. - release candidates
<dependencies>
<dependency>
<groupId>org.springframework.vault</groupId>
<artifactId>spring-vault-core</artifactId>
</dependency>
</dependencies>
8. Getting Started
Spring Vault support requires Vault 0.6 or higher and Java SE 6 or higher. An easy way to bootstrap setting up a working environment is to create a Spring based project in STS.
First you need to set up a running Vault server. Refer to the Vault for an explanation on how to startup a Vault instance.
To create a Spring project in STS go to File → New →
Spring Template Project → Simple Spring Utility Project →
press Yes when prompted. Then enter a project and a package name such as org.spring.vault.example
.
Then add the following to pom.xml
dependencies section.
<dependencies>
<!-- other dependency elements omitted -->
<dependency>
<groupId>org.springframework.vault</groupId>
<artifactId>spring-vault-core</artifactId>
<version>2.3.4</version>
</dependency>
</dependencies>
If you are using a milestone or release candidate, you will also need to add the location of the Spring
Milestone repository to your maven pom.xml
which is at the same level of your <dependencies/>
element.
<repositories>
<repository>
<id>spring-milestone</id>
<name>Spring Maven MILESTONE Repository</name>
<url>https://repo.spring.io/libs-milestone</url>
</repository>
</repositories>
The repository is also browseable here.
If you are using a SNAPSHOT, you will also need to add the location of the Spring
Snapshot repository to your maven pom.xml
which is at the same level of your <dependencies/>
element.
<repositories>
<repository>
<id>spring-snapshot</id>
<name>Spring Maven SNAPSHOT Repository</name>
<url>https://repo.spring.io/libs-snapshot</url>
</repository>
</repositories>
The repository is also browseable here.
Create a simple Secrets
class to persist:
package org.spring.vault.example;
public class Secrets {
String username;
String password;
public String getUsername() {
return username;
}
public String getPassword() {
return password;
}
}
And a main application to run
package org.springframework.vault.example;
import org.springframework.vault.authentication.TokenAuthentication;
import org.springframework.vault.client.VaultEndpoint;
import org.springframework.vault.core.VaultTemplate;
import org.springframework.vault.support.VaultResponseSupport;
public class VaultApp {
public static void main(String[] args) {
VaultTemplate vaultTemplate = new VaultTemplate(new VaultEndpoint(),
new TokenAuthentication("00000000-0000-0000-0000-000000000000"));
Secrets secrets = new Secrets();
secrets.username = "hello";
secrets.password = "world";
vaultTemplate.write("secret/myapp", secrets);
VaultResponseSupport<Secrets> response = vaultTemplate.read("secret/myapp", Secrets.class);
System.out.println(response.getData().getUsername());
vaultTemplate.delete("secret/myapp");
}
}
Even in this simple example, there are few things to take notice of
-
You can instantiate the central class of Spring Vault,
VaultTemplate
, using theorg.springframework.vault.client.VaultEndpoint
object and theClientAuthentication
. You are not required to spin up a Spring Context to use Spring Vault. -
Vault is expected to be configured with a root token of
00000000-0000-0000-0000-000000000000
to run this application. -
The mapper works against standard POJO objects without the need for any additional metadata (though you can optionally provide that information).
-
Mapping conventions can use field access. Notice the
Secrets
class has only getters. -
If the constructor argument names match the field names of the stored document, they will be used to instantiate the object.
9. Introduction to VaultTemplate
The class VaultTemplate
, located in the package org.springframework.vault.core
,
is the central class of the Spring’s Vault support providing a rich feature set to
interact with Vault. The template offers convenience operations to read, write and
delete data in Vault and provides a mapping between your domain objects and Vault data.
Once configured, VaultTemplate is thread-safe and can be reused across
multiple instances.
|
The mapping between Vault documents and domain classes is done by delegating to
RestTemplate
. Spring Web support provides the mapping infrastructure.
The VaultTemplate
class implements the interface VaultOperations
.
In as much as possible, the methods on VaultOperations
are named after methods
available on the Vault API to make the API familiar to existing Vault developers
who are used to the API and CLI. For example, you will find methods such as
"write", "delete", "read", and "revoke".
The design goal was to make it as easy as possible to transition between
the use of the Vault API and VaultOperations
. A major difference in between
the two APIs is that VaultOperations
can be passed domain objects instead of
JSON Key-Value pairs.
The preferred way to reference the operations on VaultTemplate instance
is via its interface VaultOperations .
|
While there are many convenience methods on VaultTemplate
to help you easily
perform common tasks if you should need to access the Vault API directly to access
functionality not explicitly exposed by the VaultTemplate
you can use one of
several execute callback methods to access underlying APIs. The execute callbacks
will give you a reference to a RestOperations
object.
Please see the section Execution Callbacks for more information.
Now let’s look at a examples of how to work with Vault in the context of the Spring container.
9.1. Registering and configuring Spring Vault beans
Using Spring Vault does not require a Spring Context. However, instances of VaultTemplate
and SessionManager
registered inside a managed context will participate
in lifecycle events
provided by the Spring IoC container. This is useful to dispose active Vault sessions upon
application shutdown. You also benefit from reusing the same VaultTemplate
instance across your application.
Spring Vault comes with a supporting configuration class that provides bean definitions
for use inside a Spring context. Application configuration
classes typically extend from AbstractVaultConfiguration
and are required to
provide additional details that are environment specific.
Extending from AbstractVaultConfiguration
requires to implement
` VaultEndpoint vaultEndpoint()` and ClientAuthentication clientAuthentication()
methods.
@Configuration
public class AppConfig extends AbstractVaultConfiguration {
/**
* Specify an endpoint for connecting to Vault.
*/
@Override
public VaultEndpoint vaultEndpoint() {
return new VaultEndpoint(); (1)
}
/**
* Configure a client authentication.
* Please consider a more secure authentication method
* for production use.
*/
@Override
public ClientAuthentication clientAuthentication() {
return new TokenAuthentication("…"); (2)
}
}
1 | Create a new VaultEndpoint that points by default to https://localhost:8200 . |
2 | This sample uses TokenAuthentication to get started quickly.
See Authentication Methods for details on supported authentication methods. |
@Configuration
public class AppConfig extends AbstractVaultConfiguration {
@Value("${vault.uri}")
URI vaultUri;
/**
* Specify an endpoint that was injected as URI.
*/
@Override
public VaultEndpoint vaultEndpoint() {
return VaultEndpoint.from(vaultUri); (1)
}
/**
* Configure a Client Certificate authentication.
* {@link RestOperations} can be obtained from {@link #restOperations()}.
*/
@Override
public ClientAuthentication clientAuthentication() {
return new ClientCertificateAuthentication(restOperations()); (2)
}
}
1 | VaultEndpoint can be constructed using various factory methods such as
from(URI uri) or VaultEndpoint.create(String host, int port) . |
2 | Dependencies for ClientAuthentication methods can be obtained either from
AbstractVaultConfiguration or provided by your configuration. |
Creating a custom configuration class might be cumbersome in some cases.
Take a look at EnvironmentVaultConfiguration that allows configuration by using
properties from existing property sources and Spring’s Environment . Read more
in Using EnvironmentVaultConfiguration .
|
9.2. Session Management
Spring Vault requires a ClientAuthentication
to login and access Vault.
See Authentication Methods on details regarding authentication.
Vault login should not occur on each authenticated Vault interaction but
must be reused throughout a session. This aspect is handled by a
SessionManager
implementation. A SessionManager
decides how often it
obtains a token, about revocation and renewal. Spring Vault comes with two implementations:
-
SimpleSessionManager
: Just obtains tokens from the suppliedClientAuthentication
without refresh and revocation -
LifecycleAwareSessionManager
: ThisSessionManager
schedules token renewal if a token is renewable and revoke a login token on disposal. Renewal is scheduled with anAsyncTaskExecutor
.LifecycleAwareSessionManager
is configured by default if usingAbstractVaultConfiguration
.
9.3. Using EnvironmentVaultConfiguration
Spring Vault includes EnvironmentVaultConfiguration
configure the Vault client from Spring’s Environment
and a set of predefined
property keys. EnvironmentVaultConfiguration
supports frequently applied configurations. Other configurations are supported by deriving from the most appropriate configuration class. Include EnvironmentVaultConfiguration
with @Import(EnvironmentVaultConfiguration.class)
to existing
Java-based configuration classes and supply configuration properties through any of Spring’s PropertySource
s.
@PropertySource("vault.properties")
@Import(EnvironmentVaultConfiguration.class)
public class MyConfiguration{
}
vault.uri=https://localhost:8200
vault.token=00000000-0000-0000-0000-000000000000
Property keys
-
Vault URI:
vault.uri
-
SSL Configuration
-
Keystore resource:
vault.ssl.key-store
(optional) -
Keystore password:
vault.ssl.key-store-password
(optional) -
Keystore type:
vault.ssl.key-store-type
(optional, typicallyjks
, supports alsopem
) -
Truststore resource:
vault.ssl.trust-store
(optional) -
Truststore password:
vault.ssl.trust-store-password
(optional) -
Truststore type:
vault.ssl.trust-store-type
(optional, typicallyjks
, supports alsopem
) -
Enabled SSL/TLS protocols:
vault.ssl.enabled-protocols
(since 2.3.2, optional, protocols separated with comma) -
Enabled SSL/TLS cipher suites:
vault.ssl.enabled-cipher-suites
(since 2.3.2, optional, cipher suites separated with comma)
-
-
Authentication method:
vault.authentication
(defaults toTOKEN
, supported authentication methods are:TOKEN
,APPID
,APPROLE
,AWS_EC2
,AZURE
,CERT
,CUBBYHOLE
,KUBERNETES
)
Authentication-specific property keys
-
Vault Token:
vault.token
-
AppId path:
vault.app-id.app-id-path
(defaults toapp-id
) -
AppId:
vault.app-id.app-id
-
UserId:
vault.app-id.user-id
.MAC_ADDRESS
andIP_ADDRESS
useMacAddressUserId
, respectiveIpAddressUserId
user id mechanisms. Any other value is used withStaticUserId
.
-
AppRole path:
vault.app-role.app-role-path
(defaults toapprole
) -
RoleId:
vault.app-role.role-id
-
SecretId:
vault.app-role.secret-id
(optional)
-
AWS EC2 path:
vault.aws-ec2.aws-ec2-path
(defaults toaws-ec2
) -
Role:
vault.aws-ec2.role
-
RoleId:
vault.aws-ec2.role-id
(deprecated: usevault.aws-ec2.role
instead) -
Identity Document URL:
vault.aws-ec2.identity-document
(defaults tohttp://169.254.169.254/latest/dynamic/instance-identity/pkcs7
)
-
Azure MSI path:
vault.azure-msi.azure-path
(defaults toazure
) -
Role:
vault.azure-msi.role
-
Metadata Service URL:
vault.azure-msi.metadata-service
(defaults tohttp://169.254.169.254/metadata/instance?api-version=2017-08-01
) -
Identity TokenService URL:
vault.azure-msi.identity-token-service
(defaults tohttp://169.254.169.254/metadata/identity/oauth2/token?resource=https://vault.hashicorp.com&api-version=2018-02-01
)
No configuration options.
-
Initial Vault Token:
vault.token
-
Kubernetes path:
vault.kubernetes.kubernetes-path
(defaults tokubernetes
) -
Role:
vault.kubernetes.role
-
Path to service account token file:
vault.kubernetes.service-account-token-file
(defaults to/var/run/secrets/kubernetes.io/serviceaccount/token
)
9.4. Execution callbacks
One common design feature of all Spring template classes is that all functionality is routed into one of the templates execute callback methods.
This helps ensure that exceptions and any resource management that maybe required are performed consistency.
While this was of much greater need in the case of JDBC and JMS than with Vault, it still offers a single spot for access and logging to occur.
As such, using the execute callback is the preferred way to access the Vault API
to perform uncommon operations that we’ve not exposed as methods on VaultTemplate
.
Here is a list of execute callback methods.
-
<T> T
doWithVault(RestOperationsCallback<T> callback)
Executes the givenRestOperationsCallback
, allows to interact with Vault usingRestOperations
without requiring a session. -
<T> T
doWithSession(RestOperationsCallback<T> callback)
Executes the givenRestOperationsCallback
, allows to interact with Vault in an authenticated session.
Here is an example that uses the ClientCallback
to initialize Vault:
vaultOperations.doWithVault(new RestOperationsCallback<VaultInitializationResponse>() {
@Override
public VaultInitializationResponse doWithRestOperations(RestOperations restOperations) {
ResponseEntity<VaultInitializationResponse> exchange = restOperations
.exchange("/sys/init", HttpMethod.PUT,
new HttpEntity<Object>(request),
VaultInitializationResponse.class);
return exchange.getBody();
}
});
10. Supporting for Vault’s Secret Engines
Spring Vault ships with several extensions to support Vault’s various secret engines.
Specifically, Spring Vault ships with extensions for:
-
Transform (Enterprise Feature)
-
System Backend
You can use all other backends through methods on VaultTemplate
directly (VaultTemplate.read(…)
, VaultTemplate.write(…)
).
10.1. Key-Value Version 1 ("unversioned secrets")
The kv
secrets engine is used to store arbitrary secrets within the configured physical storage for Vault.
When running the kv
secrets engine in a non-versioned way, only the most recently written value for a key is preserved.
The benefits of non-versioned kv is a reduced storage size for each key, since no additional metadata or history is stored.
Additionally, requests going to a backend configured this way are more performant because there are fewer storage calls and no locking for any given request.
Spring Vault ships with a dedicated Key-Value API to encapsulate differences between the individual Key-Value API implementations.
VaultKeyValueOperations
follows the Vault CLI design.
That’s the primary command line tool for Vault providing commands such as vault kv get
, vault kv put
and so on.
You can use this API with both Key-Value engine versions by specifying the version and mount path. The following example uses the Key-Value version 1:
VaultOperations operations = new VaultTemplate(new VaultEndpoint());
VaultKeyValueOperations keyValueOperations = operations.opsForKeyValue("secret",
VaultKeyValueOperationsSupport.KeyValueBackend.KV_1);
keyValueOperations.put("elvis", Collections.singletonMap("password", "409-52-2002"));
VaultResponse read = keyValueOperations.get("elvis");
read.getRequiredData().get("social-security-number");
VaultKeyValueOperations
supports all Key-Value operations such as put
, get
, delete
, list
.
Alternatively, the API can be used through VaultTemplate
because of its direct mapping and simple use, as keys and responses map directly to input and output keys.
The following example illustrates writing and reading a secret at mykey
.
The kv
secrets engine is mounted at secret
:
VaultOperations operations = new VaultTemplate(new VaultEndpoint());
operations.write("secret/elvis", Collections.singletonMap("social-security-number", "409-52-2002"));
VaultResponse read = operations.read("secret/elvis");
read.getRequiredData().get("social-security-number");
You can find more details about the Vault Key-Value version 1 API in the Vault reference documentation.
10.2. Key-Value Version 2 ("versioned secrets")
You can run the kv
secrets engine in one of two versions.
This section explains using version 2. When running version 2 of the kv
backend a key can retain a configurable number of versions.
You can retrieve the metadata and data of the older versions.
Additionally, you can use check-and-set operations to avoid unintentionally overwriting data.
Similar to Key-Value Version 1 ("unversioned secrets"), Spring Vault ships with a dedicated Key-Value API to encapsulate differences between the individual Key-Value API implementations.
Spring Vault ships with a dedicated Key-Value API to encapsulate differences between the individual Key-Value API implementations.
VaultKeyValueOperations
follows the Vault CLI design.
That is the primary command line tool for Vault, providing commands such as vault kv get
, vault kv put
, and so on.
You can use this API with both Key-Value engine versions by specifying the version and mount path. The following example uses Key-Value version 2:
VaultOperations operations = new VaultTemplate(new VaultEndpoint());
VaultKeyValueOperations keyValueOperations = operations.opsForKeyValue("secret",
VaultKeyValueOperationsSupport.KeyValueBackend.KV_2);
keyValueOperations.put("elvis", Collections.singletonMap("social-security-number", "409-52-2002"));
VaultResponse read = keyValueOperations.get("elvis");
read.getRequiredData().get("social-security-number");
VaultKeyValueOperations
supports all Key-Value operations, such as put
, get
, delete
, list
.
You can also interact with the specifics of the versioned key-value API. This is useful if you want to obtain a specific secret or you need access to the metadata.
VaultOperations operations = new VaultTemplate(new VaultEndpoint());
VaultVersionedKeyValueOperations versionedOperations = operations.opsForVersionedKeyValue("secret");
Versioned.Metadata metadata = versionedOperations.put("elvis", (1)
Collections.singletonMap("social-security-number", "409-52-2002"));
Version version = metadata.getVersion(); (2)
Versioned<Object> ssn = versionedOperations.get("elvis", Version.from(42)); (3)
Versioned<SocialSecurityNumber> mappedSsn = versionedOperations.get("elvis", (4)
Version.from(42), SocialSecurityNumber.class);
Versioned<Map<String,String>> versioned = Versioned.create(Collections (5)
.singletonMap("social-security-number", "409-52-2002"),
Version.from(42));
versionedOperations.put("elvis", version);
1 | Store secrets at elvis in that is available under the secret/ mount. |
2 | Storing data in the versioned backend returns metadata such as the version number. |
3 | The versioned Key-Value API allows retrieval of specific versions identified by the version number. |
4 | Versioned key-value secrets can be mapped into value objects. |
5 | When updating versioned secrets using CAS, the input must refer to the previously obtained version. |
While using the kv
v2 secrets engine through VaultTemplate
is possible.
It is not the most convenient approach since the API offers a different approach to context paths and how input/output is represented.
Specifically, interaction with the actual secrets requires wrapping and unwrapping of the data section and introducing a data/
path segment between the mount and the secrets key.
VaultOperations operations = new VaultTemplate(new VaultEndpoint());
operations.write("secret/data/elvis", Collections.singletonMap("data",
Collections.singletonMap("social-security-number", "409-52-2002")));
VaultResponse read = operations.read("secret/data/ykey");
Map<String,String> data = (Map<String, String>) read.getRequiredData().get("data");
data.get("social-security-number");
You can find more details about the Vault Key-Value version 2 API in the Vault reference documentation.
10.3. PKI (Public Key Infrastructure)
The pki
secrets engine represents a backend for certificates by implementing certificate authority operations.
The PKI secrets engine generates dynamic X.509 certificates. With this secrets engine, services can get certificates without going through the usual manual process of generating a private key and CSR, submitting to a CA, and waiting for a verification and signing process to complete. Vault’s built-in authentication and authorization mechanisms provide the verification functionality.
Spring Vault supports issuing, signing, revoking certificates, and CRL retrieval through VaultPkiOperations
.
All other PKI functionality can be used through VaultOperations
.
The following examples explain briefly the use of how to issue and revoke certificates:
VaultOperations operations = new VaultTemplate(new VaultEndpoint());
VaultPkiOperations pkiOperations = operations.opsForPki("pki");
VaultCertificateRequest request = VaultCertificateRequest.builder() (1)
.ttl(Duration.ofHours(48))
.altNames(Arrays.asList("prod.dc-1.example.com", "prod.dc-2.example.com"))
.withIpSubjectAltName("1.2.3.4")
.commonName("hello.example.com")
.build();
VaultCertificateResponse response = pkiOperations.issueCertificate("production", request); (2)
CertificateBundle certificateBundle = response.getRequiredData();
KeyStore keyStore = certificateBundle.createKeyStore("my-keystore"); (3)
KeySpec privateKey = certificateBundle.getPrivateKeySpec(); (4)
X509Certificate certificate = certificateBundle.getX509Certificate();
X509Certificate caCertificate = certificateBundle.getX509IssuerCertificate();
pkiOperations.revoke(certificateBundle.getSerialNumber()); (5)
1 | Construct a certificate request by using the VaultCertificateRequest builder. |
2 | Request a certificate from Vault.
Vault acts as certificate authority and responds with a signed X.509 certificate.
The actual response is a CertificateBundle . |
3 | You can obtain generated certificates directly as Java KeyStore that contains public and private keys as well as the issuer certificate. KeyStore has a wide range of uses, which makes this format suitable to configure (for example a HTTP client, a database driver, or an SSL-secured HTTP server). |
4 | CertificateBundle allows accessing the private key and the public and issuer certificates directly through the Java Cryptography Extension API. |
5 | Once a certificate is no longer in use (or it was compromised), you can revoke it through its serial number. Vault includes the revoked certificate in its CRL. |
You can find more details about the Vault PKI secrets API in the Vault reference documentation.
10.4. Token Authentication Backend
This backend is an authentication backend that does not interact with actual secrets. Rather, it gives access to access token management. You can read more about Token-based authentication in the authentication methods chapter.
The token
authentication method is built-in and automatically available at /auth/token
.
It lets users authenticate using a token, as well to create new tokens, revoke secrets by token, and more.
When any other auth method returns an identity, Vault core invokes the token method to create a new unique token for that identity.
You can also use the token store to bypass any other auth method. You can create tokens directly, as well as perform a variety of other operations on tokens, such as renewal and revocation.
Spring Vault uses this backend to renew and revoke the session tokens supplied by the configured authentication method.
The following examples show how to request, renew and revoke a Vault token from within your application:
VaultOperations operations = new VaultTemplate(new VaultEndpoint());
VaultTokenOperations tokenOperations = operations.opsForToken();
VaultTokenResponse tokenResponse = tokenOperations.create(); (1)
VaultToken justAToken = tokenResponse.getToken();
VaultTokenRequest tokenRequest = VaultTokenRequest.builder().withPolicy("policy-for-myapp")
.displayName("Access tokens for myapp")
.renewable()
.ttl(Duration.ofHours(1))
.build();
VaultTokenResponse appTokenResponse = tokenOperations.create(tokenRequest); (2)
VaultToken appToken = appTokenResponse.getToken();
tokenOperations.renew(appToken); (3)
tokenOperations.revoke(appToken); (4)
1 | Create an token by applying role defaults. |
2 | Using the builder API, you can define fine-grained settings for the token to request.
Requesting a token returns a VaultToken , which is used as value object for Vault tokens. |
3 | You can renew tokens through the Token API. Typically, that is done by SessionManager to keep track of the Vault session token. |
4 | Tokens can be revoked if needed through the Token API. Typically, that is done by SessionManager to keep track of the Vault session token. |
You can find more details about the Vault Token Auth Method API in the Vault reference documentation.
10.5. Transit Backend
The transit secrets engine handles cryptographic functions on data in-transit. Vault does not store the data sent to this secrets engine. It can also be seen as "cryptography as a service" or "encryption as a service". The transit secrets engine can also sign and verify data, generate hashes and HMACs of data, and act as a random bytes source.
The primary use case for transit is to encrypt data from applications while still storing that encrypted data in some primary data store. This relieves the burden of proper encryption and decryption from application developers and pushes the burden onto the operators of Vault.
Spring Vault supports a wide range of Transit operations:
-
Key creation
-
Key reconfiguration
-
Encryption/Decryption/Rewrapping
-
HMAC computation
-
Signing and signature verification
All operations within transit
are centered around keys.
The Transit engine supports the versioning of keys and a variety of key types.
Note that the key type may impose a limitation on which operations can used.
The following examples shows how to create a key and how to encrypt and decrypt data:
VaultOperations operations = new VaultTemplate(new VaultEndpoint());
VaultTransitOperations transitOperations = operations.opsForTransit("transit");
transitOperations.createKey("my-aes-key", VaultTransitKeyCreationRequest.ofKeyType("aes128-gcm96")); (1)
String ciphertext = transitOperations.encrypt("my-aes-key", "plaintext to encrypt"); (2)
String plaintext = transitOperations.decrypt("my-aes-key", ciphertext); (3)
1 | First, we need a key to begin with.
Each key requires the type to be specified. aes128-gcm96 supports encryption, decryption, key derivation, and convergent encryption, of which we need encryption and decryption for this example. |
2 | Next, we encrypt a String that contains the plain text that should be encrypted.
The input String uses the default Charset to encode the string into its binary representation.
Requesting a token returns a VaultToken , which is used as value object for Vault tokens.
The encrypt method returns Base64-encoded ciphertext, typically starting with vault: . |
3 | To decrypt ciphertext into plain text, call the decrypt method.
It decrypts the ciphertext and returns a String that is decoded using the default charset. |
The preceeding example uses simple strings for cryptographic operations. While it is a simple approach, it bears the risk of charset misconfiguration and is not binary-safe. Binary safety is required when the plain text uses a binary representation for data such as images, compressed data, or binary data structures.
To encrypt and decrypt binary data, use the Plaintext
and Ciphertext
value objects that can hold binary values:
byte [] plaintext = "plaintext to encrypt".getBytes();
Ciphertext ciphertext = transitOperations.encrypt("my-aes-key", Plaintext.of(plaintext)); (1)
Plaintext decrypttedPlaintext = transitOperations.decrypt("my-aes-key", ciphertext); (2)
1 | Assuming a key my-aes-key is already in place, we’re encrypting the Plaintext object.
In return, the encrypt method returns a Ciphertext object. |
2 | The Ciphertext object can be used directly for decryption and returns a Plaintext object. |
Plaintext
and Ciphertext
come with a contextual object, VaultTransitContext
.
It is used to supply a nonce value for convergent encryption and for a context value to make use of key derivation.
Transit allows for signing plain text and verifying the signature for a given plain text. Sign operations require an asymmetric key, typically using Elliptic Curve Cryptography or RSA.
Signatures use the public/private key split to ensure authenticity. The signer uses its private key to create a signature. Otherwise, anybody would be able to sign messages in your name. The verifier uses the public key part to verify the signature. The actual signature is typically a hash value. Internally, the hash gets computed and encrypted using the private key to create the final signature. The verification decrypts the signature message, computes their own hash for the plain text and compares both hash values to check whether the signature is valid or not. |
byte [] plaintext = "plaintext to sign".getBytes();
transitOperations.createKey("my-ed25519-key", VaultTransitKeyCreationRequest.ofKeyType("ed25519")); (1)
Signature signature = transitOperations.sign("my-ed25519-key", Plaintext.of(plaintext)); (2)
boolean valid = transitOperations.verify("my-ed25519-key", Plaintext.of(plaintext), signature); (3)
1 | Signing requires an asymmetric key. You can use any Elliptic Curve Cryptography or RSA key type. Once the key is created, you have all the prerequisites in place to create a signature. |
2 | The signature gets created for a plain text message. The returned Signature contains an ASCII-safe string that uses Base64 characters. |
3 | To verify the signature, the verification requires a Signature object and the plain text message. As the return value, you get whether the signature was valid or not. |
You can find more details about the Vault Transit Backend in the Vault reference documentation.
11. Introduction to ReactiveVaultTemplate
This section covers basic information on the reactive programming support using Spring Vault.
11.1. What is Reactive Programming?
In plain terms reactive programming is about non-blocking applications that are asynchronous and event-driven and require a small number of threads to scale vertically (i.e. within the JVM) rather than horizontally (i.e. through clustering).
A key aspect of reactive applications is the concept of backpressure which is a mechanism to ensure producers don’t overwhelm consumers. For example in a pipeline of reactive components extending from the database to the HTTP response when the HTTP connection is too slow the data repository can also slow down or stop completely until network capacity frees up.
11.2. Reactive Vault Client
Spring Vault’s reactive client support is built on top of composable authentication steps and Spring’s functional WebClient
via Reactor Netty or Jetty, which feature both a fully non-blocking, event-driven HTTP client.
It exposes VaultTokenSupplier
as supplier of VaultToken
to authenticate HTTP requests
and ReactiveVaultOperations
as the primary entry point. The core configuration of
VaultEndpoint
, ClientOptions
and SSL are reused across the
various client implementation.
The class ReactiveVaultTemplate
, located in the package org.springframework.vault.core
,
is the central class of the Spring’s reactive Vault support providing a rich feature set to
interact with Vault. The template offers convenience operations to read, write and
delete data in Vault and provides a mapping between your domain objects and Vault data.
Once configured, ReactiveVaultTemplate is thread-safe and can be reused across
multiple instances.
|
The mapping between Vault documents and domain classes is done by delegating to
WebClient
and its codecs.
The ReactiveVaultTemplate
class implements the interface ReactiveVaultOperations
.
In as much as possible, the methods on ReactiveVaultOperations
are named after methods
available on the Vault API to make the API familiar to existing Vault developers
who are used to the API and CLI. For example, you will find methods such as
"write", "delete", and "read".
The design goal was to make it as easy as possible to transition between
the use of the Vault API and ReactiveVaultOperations
. A major difference in between
the two APIs is that ReactiveVaultOperations
can be passed domain objects instead of
JSON Key-Value pairs.
The preferred way to reference the operations on ReactiveVaultTemplate instance
is via its interface ReactiveVaultOperations .
|
Functionality not explicitly exposed by the ReactiveVaultTemplate
you can use one of
several execute callback methods to access underlying APIs. The execute callbacks
will give you a reference to a WebClient
object.
Please see the section Execution Callbacks for more information.
Now let’s look at a examples of how to work with Vault in the context of the Spring container.
11.3. Registering and configuring Spring Vault beans
Using Spring Vault does not require a Spring Context. However, instances of
ReactiveVaultTemplate
and VaultTokenSupplier
registered inside a managed context will participate
in lifecycle events
provided by the Spring IoC container. This is useful to dispose active Vault sessions upon
application shutdown. You also benefit from reusing the same ReactiveVaultTemplate
instance across your application.
Spring Vault comes with a supporting configuration class that provides bean definitions
for use inside a Spring context. Application configuration
classes typically extend from AbstractVaultConfiguration
and are required to
provide additional details that are environment specific.
Extending from AbstractVaultConfiguration
requires to implement
` VaultEndpoint vaultEndpoint()` and ClientAuthentication clientAuthentication()
methods.
@Configuration
public class AppConfig extends AbstractReactiveVaultConfiguration {
/**
* Specify an endpoint for connecting to Vault.
*/
@Override
public VaultEndpoint vaultEndpoint() {
return new VaultEndpoint(); (1)
}
/**
* Configure a client authentication.
* Please consider a more secure authentication method
* for production use.
*/
@Override
public ClientAuthentication clientAuthentication() {
return new TokenAuthentication("…"); (2)
}
}
1 | Create a new VaultEndpoint that points by default to https://localhost:8200 . |
2 | This sample uses TokenAuthentication to get started quickly.
See Authentication Methods for details on supported authentication methods. |
11.4. Session Management
Spring Vault requires a token to authenticate Vault requests.
See Authentication Methods on details regarding authentication.
The reactive client requires a non-blocking token supplier whose contract is defined
in VaultTokenSupplier
. Tokens can be static or obtained through a
declared authentication flow.
Vault login should not occur on each authenticated Vault interaction but
the session token should be kept across a session. This aspect is handled by a
session manager implementing ReactiveSessionManager
, such as ReactiveLifecycleAwareSessionManager
.
11.5. Execution callbacks
One common design feature of all Spring template classes is that all functionality
is routed into one of the templates execute callback methods. This helps ensure
that exceptions and any resource management that maybe required are performed
consistency. While this was of much greater need in the case of JDBC and JMS
than with Vault, it still offers a single spot for access and logging to occur.
As such, using the execute callback is the preferred way to access the Vault API
to perform uncommon operations that we’ve not exposed as methods on ReactiveVaultTemplate
.
Here is a list of execute callback methods.
-
<T> T
doWithVault(Function<WebClient, ? extends T> clientCallback)
Composes a reactive sequence the givenWebClient
, allows to interact with Vault without a session context. -
<T> T
doWithSession(Function<WebClient, ? extends T> clientCallback)
Composes a reactive sequence the givenWebClient
, allows to interact with Vault in an authenticated session.
Here is an example that uses the callback to initialize Vault:
reactiveVaultOperations.doWithVault(webClient -> {
return webClient.put()
.uri("/sys/init")
.syncBody(request)
.retrieve()
.toEntity(VaultInitializationResponse.class);
});
12. Vault Property Source Support
Vault can be used in many different ways. One specific use-case is using Vault to store encrypted properties. Spring Vault supports Vault as property source to obtain configuration properties using Spring’s PropertySource abstraction.
You can reference properties stored inside Vault in other property sources or use value injection with @Value(…) . Special attention is required when bootstrapping beans that require data stored inside of Vault. A VaultPropertySource must be initialized at that time to retrieve properties from Vault.
|
Spring Boot/Spring Cloud users can benefit from Spring Cloud Vault's configuration integration that initializes various property sources during application startup. |
12.1. Registering VaultPropertySource
Spring Vault provides a VaultPropertySource
to be used with Vault to obtain
properties. It uses the nested data
element to expose properties stored and
encrypted in Vault.
ConfigurableApplicationContext ctx = new GenericApplicationContext();
MutablePropertySources sources = ctx.getEnvironment().getPropertySources();
sources.addFirst(new VaultPropertySource(vaultTemplate, "secret/my-application"));
In the code above, VaultPropertySource
has been added with highest precedence
in the search. If it contains a ´foo` property, it will be detected and returned
ahead of any foo
property in any other PropertySource
.
MutablePropertySources
exposes a number of methods that allow for precise
manipulation of the set of property sources.
12.2. @VaultPropertySource
The @VaultPropertySource
annotation provides a convenient and declarative
mechanism for adding a PropertySource
to Spring’s Environment
to be used in conjunction with @Configuration
classes.
@VaultPropertySource
takes a Vault path such as secret/my-application
and exposes the data stored at the node in a PropertySource
.
@VaultPropertySource
supports lease renewal for secrets associated with a lease
(i. e. credentials from the mysql
backend) and credential rotation upon terminal
lease expiration. Lease renewal is disabled by default.
{
// …
"data": {
"database": {
"password": ...
},
"user.name": ...,
}
// …
}
@VaultPropertySource
@Configuration
@VaultPropertySource("secret/my-application")
public class AppConfig {
@Autowired Environment env;
@Bean
public TestBean testBean() {
TestBean testBean = new TestBean();
testBean.setUser(env.getProperty("user.name"));
testBean.setPassword(env.getProperty("database.password"));
return testBean;
}
}
@VaultPropertySource
with credential rotation and prefix@Configuration
@VaultPropertySource(value = "aws/creds/s3-access",
propertyNamePrefix = "aws.",
renewal = Renewal.ROTATE)
public class AppConfig {
// provides aws.access_key and aws.secret_key properties
}
Secrets obtained from generic secret backends are associated with a TTL (refresh_interval ) but not a lease Id. Spring Vault’s PropertySource rotates generic secrets when reaching its TTL.
|
You can use @VaultPropertySource to obtain the newest secret version from the versioned Key-Value backend. Make sure to not include the data/ segment in the path.
|
Any ${…}
placeholders present in a @VaultPropertySource
path are resolved against the set of property sources already registered against the environment, as the following example shows:
@VaultPropertySource
path using placeholders@Configuration
@VaultPropertySource(value = "aws/creds/${my.placeholder:fallback/value}",
propertyNamePrefix = "aws.",
renewal = Renewal.ROTATE)
public class AppConfig {
}
Assuming that my.placeholder
is present in one of the property sources already registered (for example, system properties or environment variables), the placeholder is resolved to the corresponding value.
If not, then fallback/value
is used as a default.
If no default is specified and a property cannot be resolved, an IllegalArgumentException
is thrown.
In certain situations, it may not be possible or practical to tightly control
property source ordering when using @VaultPropertySource
annotations.
For example, if the @Configuration
classes above were registered via
component-scanning, the ordering is difficult to predict.
In such cases - and if overriding is important - it is recommended that the
user fall back to using the programmatic PropertySource API.
See ConfigurableEnvironment
and
MutablePropertySources
for details.
13. Vault Repositories
Working with VaultTemplate
and responses mapped to Java classes allows basic data operations like read, write
and delete. Vault repositories apply Spring Data’s repository concept on top of Vault.
A Vault repository exposes basic CRUD functionality and supports query derivation with predicates constraining
the Id property, paging and sorting.
Read more about Spring Data Repositories in the Spring Data Commons reference documentation. The reference documentation will give you an introduction to Spring Data repositories. |
13.1. Usage
To access domain entities stored in Vault you can leverage repository support that eases implementing those quite significantly.
@Secret
public class Credentials {
@Id String id;
String password;
String socialSecurityNumber;
Address address;
}
We have a pretty simple domain object here. Note that it has a property named id
annotated with
org.springframework.data.annotation.Id
and a @Secret
annotation on its type.
Those two are responsible for creating the actual key used to persist the object as JSON inside Vault.
Properties annotated with @Id as well as those named id are considered as the identifier properties.
Those with the annotation are favored over others.
|
The next step is to declare a repository interface that uses the domain object.
Credentials
entitiespublic interface CredentialsRepository extends CrudRepository<Credentials, String> {
}
As our repository extends CrudRepository
it provides basic CRUD and query methods. Vault repositories
require Spring Data components. Make sure to include spring-data-commons
and spring-data-keyvalue
artifacts in your class path.
The easiest way to achive this, is by setting up dependency management and adding the artifacts to your pom.xml
:
Then add the following to pom.xml
dependencies section.
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-bom</artifactId>
<version>2020.0.15</version>
<scope>import</scope>
<type>pom</type>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<!-- other dependency elements omitted -->
<dependency>
<groupId>org.springframework.vault</groupId>
<artifactId>spring-vault-core</artifactId>
<version>2.3.4</version>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-keyvalue</artifactId>
<!-- Version inherited from the BOM -->
</dependency>
</dependencies>
The thing we need in between to glue things together is the according Spring configuration.
@Configuration
@EnableVaultRepositories
public class ApplicationConfig {
@Bean
public VaultTemplate vaultTemplate() {
return new VaultTemplate(…);
}
}
Given the setup above we can go on and inject CredentialsRepository
into our components.
@Autowired CredentialsRepository repo;
public void basicCrudOperations() {
Credentials creds = new Credentials("heisenberg", "327215", "AAA-GG-SSSS");
rand.setAddress(new Address("308 Negra Arroyo Lane", "Albuquerque", "New Mexico", "87104"));
repo.save(creds); (1)
repo.findOne(creds.getId()); (2)
repo.count(); (3)
repo.delete(creds); (4)
}
1 | Stores properties of Credentials inside Vault Hash with a key pattern keyspace/id ,
in this case credentials/heisenberg , in the generic secret backend. |
2 | Uses the provided id to retrieve the object stored at keyspace/id . |
3 | Counts the total number of entities available within the keyspace credentials defined by @Secret on Credentials . |
4 | Removes the key for the given object from Vault. |
13.2. Object to Vault JSON Mapping
Vault repositories store objects in Vault using JSON as interchange format. Object mapping between JSON and
the entity is done by VaultConverter
. The converter reads and writes SecretDocument
that contains the body
from a VaultResponse
. VaultResponse
s are read from Vault and the body is deserialized by
Jackson into a Map
of String
and Object
.
The default VaultConverter
implementation reads the Map
with nested values, List
and Map
objects and
converts these to entities and vice versa.
Given the Credentials
type from the previous sections the default mapping is as follows:
{
"_class": "org.example.Credentials", (1)
"password": "327215", (2)
"socialSecurityNumber": "AAA-GG-SSSS",
"address": { (3)
"street": "308 Negra Arroyo Lane",
"city": "Albuquerque",
"state": "New Mexico",
"zip": "87104"
}
}
1 | The _class attribute is included on root level as well as on any nested interface or abstract types. |
2 | Simple property values are mapped by path. |
3 | Properties of complex types are mapped as nested objects. |
The @Id property must be mapped to String .
|
Type | Sample | Mapped Value |
---|---|---|
Simple Type |
String firstname = "Walter"; |
"firstname": "Walter" |
Complex Type |
Address adress = new Address("308 Negra Arroyo Lane"); |
"address": { "street": "308 Negra Arroyo Lane" } |
List |
List<String> nicknames = asList("walt", "heisenberg"); |
"nicknames": ["walt", "heisenberg"] |
Map |
Map<String, Integer> atts = asMap("age", 51) |
"atts" : {"age" : 51} |
List |
List<Address> addresses = asList(new Address("308… |
"address": [{ "street": "308 Negra Arroyo Lane" }, …] |
You can customize the mapping behavior by registering a Converter
in VaultCustomConversions
.
Those converters can take care of converting from/to a type such as LocalDate
as well as SecretDocument
whereas the first one is suitable for converting simple properties and the last one complex types to their JSON
representation. The second option offers full control over the resulting SecretDocument
. Writing objects to Vault
will delete the content and re-create the whole entry, so not mapped data will be lost.
13.3. Queries and Query Methods
Query methods allow automatic derivation of simple queries from the method name. Vault has no query engine but requires direct access of HTTP context paths. Vault query methods translate Vault’s API possibilities to queries. A query method execution lists children under a context path, applies filtering to the Id, optionally limits the Id stream with offset/limit and applies sorting after fetching the results.
public interface CredentialsRepository extends CrudRepository<Credentials, String> {
List<Credentials> findByIdStartsWith(String prefix);
}
Query methods for Vault repositories support only queries with predicates on the @Id property.
|
Here’s an overview of the keywords supported for Vault.
Keyword | Sample |
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13.3.1. Sorting and Paging
Query methods support sorting and paging by selecting in memory a sublist (offset/limit) Id’s retrieved from a Vault context path. Sorting has is not limited to a particular field, unlike query method predicates. Unpaged sorting is applied after Id filtering and all resulting secrets are fetched from Vault. This way a query method fetches only results that are also returned as part of the result.
Using paging and sorting requires secret fetching before filtering the Id’s which impacts performance. Sorting and paging guarantees to return the same result even if the natural order of Id returned by Vault changes. Therefore, all Id’s are fetched from Vault first, then sorting is applied and afterwards filtering and offset/limiting.
public interface CredentialsRepository extends PagingAndSortingRepository<Credentials, String> {
List<Credentials> findTop10ByIdStartsWithOrderBySocialSecurityNumberDesc(String prefix);
List<Credentials> findByIdStarts(String prefix, Pageable pageRequest);
}
14. Client support
Spring Vault supports various HTTP clients to access Vault’s HTTP API. Spring Vault uses
RestTemplate
as primary interface accessing Vault.
Dedicated client support originates from customized SSL configuration
that is scoped only to Spring Vault’s client components.
Spring Vault supports following HTTP imperative clients:
-
Java’s builtin
HttpURLConnection
(default client) -
Apache Http Components
-
Netty
-
OkHttp 3
Spring Vault’s reactive integration supports the following reactive HTTP clients:
-
Reactor Netty
-
Jetty
Using a specific client requires the according dependency to be available on the classpath so Spring Vault can use the available client for communicating with Vault.
14.1. Java’s builtin HttpURLConnection
Java’s builtin HttpURLConnection
is available out-of-the-box without additional
configuration. Using HttpURLConnection
comes with a limitation regarding SSL configuration.
Spring Vault won’t apply customized SSL configuration as it would
require a deep reconfiguration of the JVM. This configuration would affect all
components relying on the default SSL context. Configuring SSL settings using
HttpURLConnection
requires you providing these settings as System Properties. See
Customizing JSSE for further details.
14.2. External Clients
You can use external clients to access Vault’s API. Simply add one of the following dependencies to your project. You can omit the version number if using Spring Vault’s Dependency BOM
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
</dependency>
Apache HttpClient’s wire logging can be enabled through logging configuration. Make sure to not accidentally enable wire logging as logs may expose traffic (tokens and secrets) between your application and Vault in plain text. |
<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
</dependency>
<dependency>
<groupId>com.squareup.okhttp3</groupId>
<artifactId>okhttp</artifactId>
</dependency>
<dependency>
<groupId>io.projectreactor.netty</groupId>
<artifactId>reactor-netty</artifactId>
</dependency>
<dependency>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-reactive-httpclient</artifactId>
</dependency>
14.3. Vault Client SSL configuration
SSL can be configured using SslConfiguration
by setting various properties.
You can set either javax.net.ssl.trustStore
to configure
JVM-wide SSL settings or configure SslConfiguration
to set SSL settings only for Spring Vault.
SslConfiguration sslConfiguration = SslConfiguration.create( (1)
new FileSystemResource("client-cert.jks"), "changeit".toCharArray(),
new FileSystemResource("truststore.jks"), "changeit".toCharArray());
SslConfiguration.forTrustStore(new FileSystemResource("keystore.jks"), (2)
"changeit".toCharArray())
SslConfiguration.forKeyStore(new FileSystemResource("keystore.jks"), (3)
"changeit".toCharArray())
SslConfiguration.forKeyStore(new FileSystemResource("keystore.jks"), (4)
"changeit".toCharArray(),
KeyConfiguration.of("key-password".toCharArray(),
"my-key-alias"))
1 | Full configuration. |
2 | Configuring only trust store settings. |
3 | Configuring only key store settings. |
4 | Configuring only key store settings with providing a key-configuration. |
Please note that providing SslConfiguration
can be only applied when either Apache Http Components or the OkHttp client is on your class-path.
The SSL configuration supports also PEM-encoded certificates as alternative to a Java Key Store.
KeyStoreConfiguration keystore = KeyStoreConfiguration
.of(new ClassPathResource("ca.pem")).withStoreType("PEM");
SslConfiguration configuration = SslConfiguration.forTrustStore(keystore);
PEM files may contain one or more certificates (blocks of -----BEGIN CERTIFICATE-----
and -----END CERTIFICATE-----
).
Certificates added to the underlying KeyStore
use the full subject name as alias.
15. Authentication Methods
Different organizations have different requirements for security and authentication. Vault reflects that need by shipping multiple authentication methods. Spring Vault supports multiple authentications mechanisms.
15.1. Externalizing login credentials
Obtaining first-time access to a secured system is known as secure introduction. Any client requires ephemeral or permanent credentials to access Vault. Externalizing credentials is a good pattern to keep code maintainability high but comes at a risk of increased disclosure.
Disclosure of login credentials to any party allows login to Vault and access secrets that are permitted by the underlying role. Picking the appropriate client authentication and injecting credentials into the application is subject to risk evaluation.
Spring’s PropertySource abstraction is a natural fit to keep configuration outside the application code. You can use system properties, environment variables or property files to store login credentials. Each approach comes with its own properties. Keep in mind that the command line and environment properties can be introspected with appropriate OS access levels.
vault.token
to a properties file@PropertySource("configuration.properties")
@Configuration
public class Config extends AbstractVaultConfiguration {
@Override
public ClientAuthentication clientAuthentication() {
return new TokenAuthentication(getEnvironment().getProperty("vault.token"));
}
}
Spring allows multiple ways to obtain Environment . When using VaultPropertySource , injection via @Autowired Environment environment will not provide the Environment as the environment bean is still in construction and autowiring comes at a later stage. Your configuration class should rather implement ApplicationContextAware and obtain the Environment from ApplicationContext .
|
See SecurePropertyUsage.java
for a sample on referencing properties in components and other property sources.
15.2. Token authentication
Tokens are the core method for authentication within Vault. Token authentication requires a static token to be provided.
Token authentication is the default authentication method. If a token is disclosed an unintended party, it gains access to Vault and can access secrets for the intended client. |
Typically, Token authentication is used in scenarios in which the token is created and renewed
externally (such as HashiCorp Vault service broker).
Depending on the actual setup, you may or may not want token renewal and revocation.
See LifecycleAwareSessionManager
for details about TTL and token revocation.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
return new TokenAuthentication("…");
}
// …
}
See also:
15.3. AppId authentication
AppId authentication is deprecated by Vault. Use AppRole authentication instead. |
Vault supports AppId
authentication that consists of two hard to guess tokens. The AppId
defaults to spring.application.name
that is statically configured.
The second token is the UserId which is a part determined by the application,
usually related to the runtime environment. IP address, Mac address or a
Docker container name are good examples. Spring Vault supports
IP address, Mac address and static UserId’s (e.g. supplied via System properties).
The IP and Mac address are represented as Hex-encoded SHA256 hash.
IP address-based UserId’s use the local host’s IP address.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
AppIdAuthenticationOptions options = AppIdAuthenticationOptions.builder()
.appId("myapp")
.userIdMechanism(new IpAddressUserId())
.build();
return new AppIdAuthentication(options, restOperations());
}
// …
}
The corresponding command to generate the IP address UserId from a command line is:
$ echo -n 192.168.99.1 | sha256sum
Including the line break of echo leads to a different hash value
so make sure to include the -n flag.
|
Mac address-based UserId’s obtain their network device from the
localhost-bound device. The configuration also allows specifying
a network-interface
hint to pick the right device. The value of
network-interface
is optional and can be either an interface
name or interface index (0-based).
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
AppIdAuthenticationOptions options = AppIdAuthenticationOptions.builder()
.appId("myapp")
.userIdMechanism(new MacAddressUserId())
.build();
return new AppIdAuthentication(options, restOperations());
}
// …
}
The corresponding command to generate the Mac address UserId from a command line is:
$ echo -n 0AFEDE1234AC | sha256sum
The Mac address is specified uppercase and without colons.
Including the line break of echo leads to a different hash value
so make sure to include the -n flag.
|
15.3.1. Custom UserId
A more advanced approach lets you implementing your own AppIdUserIdMechanism
.
This class must be on your classpath and must implement
the org.springframework.vault.authentication.AppIdUserIdMechanism
interface
and the createUserId
method. Spring Vault will obtain the UserId
by calling createUserId
each time it authenticates using AppId to
obtain a token.
public class MyUserIdMechanism implements AppIdUserIdMechanism {
@Override
public String createUserId() {
String userId = …
return userId;
}
}
15.4. AppRole authentication
AppRole allows machine authentication, like the deprecated (since Vault 0.6.1) AppId authentication. AppRole authentication consists of two hard to guess (secret) tokens: RoleId and SecretId.
Spring Vault supports AppRole authentication by providing either RoleId only or together with a provided SecretId and fetching RoleId/SecretId from Vault (push and pull modes with response unwrapping).
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
AppRoleAuthenticationOptions options = AppRoleAuthenticationOptions.builder()
.roleId(RoleId.provided("…"))
.secretId(SecretId.wrapped(VaultToken.of("…")))
.build();
return new AppRoleAuthentication(options, restOperations());
}
// …
}
Spring Vault also support full pull mode: If RoleId and SecretId are not provided, Spring Vault will retrieve them using the role name and an initial token. The initial token may be associated with a TTL and usage limit.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
VaultToken initialToken = VaultToken.of("…");
AppRoleAuthenticationOptions options = AppRoleAuthenticationOptions.builder()
.appRole("…")
.roleId(RoleId.pull(initialToken))
.secretId(SecretId.pull(initialToken))
.build();
return new AppRoleAuthentication(options, restOperations());
}
// …
}
15.5. AWS-EC2 authentication
The aws-ec2 auth backend provides a secure introduction mechanism for AWS EC2 instances, allowing automated retrieval of a Vault token. Unlike most Vault authentication backends, this backend does not require first-deploying, or provisioning security-sensitive credentials (tokens, username/password, client certificates, etc.). Instead, it treats AWS as a Trusted Third Party and uses the cryptographically signed dynamic metadata information that uniquely represents each EC2 instance.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
return new AwsEc2Authentication(restOperations());
}
// …
}
AWS-EC2 authentication enables nonce by default to follow the Trust On First Use (TOFU) principle. Any unintended party that gains access to the PKCS#7 identity metadata can authenticate against Vault.
During the first login, Spring Vault generates a nonce that is stored in the auth backend aside the instance Id. Re-authentication requires the same nonce to be sent. Any other party does not have the nonce and can raise an alert in Vault for further investigation.
The nonce is kept in memory and is lost during application restart.
AWS-EC2 authentication roles are optional and default to the AMI.
You can configure the authentication role by setting
it in AwsEc2AuthenticationOptions
.
15.6. AWS-IAM authentication
The aws auth backend allows Vault login by using existing AWS IAM credentials.
AWS IAM authentication creates a signed HTTP request that is
executed by Vault to get the identity of the signer using AWS STS
GetCallerIdentity
method. AWSv4 signatures require IAM credentials.
IAM credentials can be obtained from either the runtime environment or supplied externally. Runtime environments such as AWS-EC2, Lambda and ECS with assigned IAM principals do not require client-specific configuration of credentials but can obtain these from its metadata source.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
AwsIamAuthenticationOptions options = AwsIamAuthenticationOptions.builder()
.credentials(new BasicAWSCredentials(…)).build();
return new AwsIamAuthentication(options, restOperations());
}
// …
}
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
AwsIamAuthenticationOptions options = AwsIamAuthenticationOptions.builder()
.credentialsProvider(InstanceProfileCredentialsProvider.getInstance()).build();
return new AwsIamAuthentication(options, restOperations());
}
// …
}
AwsIamAuthentication
requires the AWS Java SDK dependency (com.amazonaws:aws-java-sdk-core
)
as the authentication implementation uses AWS SDK types for credentials and request signing.
You can configure the authentication via AwsIamAuthenticationOptions
.
See also:
15.7. Azure (MSI) authentication
The azure auth backend provides a secure introduction mechanism for Azure VM instances, allowing automated retrieval of a Vault token. Unlike most Vault authentication backends, this backend does not require first-deploying, or provisioning security-sensitive credentials (tokens, username/password, client certificates, etc.). Instead, it treats Azure as a Trusted Third Party and uses the managed service identity and instance metadata information that can be bound to a VM instance.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
AzureMsiAuthenticationOptions options = AzureMsiAuthenticationOptions.builder()
.role(…).build();
return new AzureMsiAuthentication(options, restOperations());
}
// …
}
Azure authentication requires details about the VM environment (subscription Id,
resource group name, VM name). These details can be either configured through
AzureMsiAuthenticationOptionsBuilder
.
If left unconfigured, AzureMsiAuthentication
queries Azure’s instance metadata service to
obtain these details.
See also:
15.8. GCP-GCE authentication
The gcp auth backend allows Vault login by using existing GCP (Google Cloud Platform) IAM and GCE credentials.
GCP GCE (Google Compute Engine) authentication creates a signature in the form of a JSON Web Token (JWT) for a service account. A JWT for a Compute Engine instance is obtained from the GCE metadata service using Instance identification. This API creates a JSON Web Token that can be used to confirm the instance identity.
Unlike most Vault authentication backends, this backend does not require first-deploying, or provisioning security-sensitive credentials (tokens, username/password, client certificates, etc.). Instead, it treats GCP as a Trusted Third Party and uses the cryptographically signed dynamic metadata information that uniquely represents each GCP service account.
You can configure the authentication via GcpComputeAuthenticationOptions
.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
GcpComputeAuthenticationOptions options = GcpComputeAuthenticationOptions.builder()
.role(…).build();
GcpComputeAuthentication authentication = new GcpComputeAuthentication(options,
restOperations());
}
// …
}
See also:
15.9. GCP-IAM authentication
The gcp auth backend allows Vault login by using existing GCP (Google Cloud Platform) IAM and GCE credentials.
GCP IAM authentication creates a signature in the form of a JSON Web Token (JWT)
for a service account. A JWT for a service account is obtained by
calling GCP IAM’s projects.serviceAccounts.signJwt
API. The caller authenticates against GCP IAM
and proves thereby its identity. This Vault backend treats GCP as a Trusted Third Party.
IAM credentials can be obtained from either the runtime environment
or supplied externally as e.g. JSON. JSON is the preferred form as it
carries the project id and service account identifier required for calling
projects.serviceAccounts.signJwt
.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
GcpIamCredentialsAuthenticationOptions options = GcpIamCredentialsAuthenticationOptions.builder()
.role(…).credential(GoogleCredentials.getApplicationDefault()).build();
GcpIamCredentialsAuthentication authentication = new GcpIamCredentialsAuthentication(options,
restOperations());
}
// …
}
GcpIamCredentialsAuthenticationOptions
requires the Google Cloud Java SDK dependency
(com.google.cloud:google-cloud-iamcredentials
)
as the authentication implementation uses Google APIs for credentials and JWT signing.
You can configure the authentication via GcpIamCredentialsAuthenticationOptions
.
Google credentials require an OAuth 2 token maintaining the token lifecycle. All API
is synchronous therefore, GcpIamCredentialsAuthentication does not support AuthenticationSteps which is
required for reactive usage.
|
GcpIamCredentialsAuthentication uses the IAM Credentials API and is a replacement using the for the deprecated GcpIamAuthentication using the deprecated IAM API.
|
See also:
15.10. PCF authentication
The pcf auth backend allows Vault login for PCF instances. It leverages PCF’s App and Container Identity Assurance.
PCF authentication uses the instance key and certificate to create a signature that is validated by Vault. If the signature matches, and potentially bound organization/space/application Id’s match, Vault issues an appropriately-scoped token.
Instance credentials are available from files at CF_INSTANCE_CERT
and
CF_INSTANCE_KEY
variables.
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
PcfAuthenticationOptions options = PcfAuthenticationOptions.builder()
.role(…).build();
PcfAuthentication authentication = new PcfAuthentication(options,
restOperations());
}
// …
}
PcfAuthenticationOptions
requires the BouncyCastle
library for creating RSA-PSS signatures.
You can configure the authentication via PcfAuthenticationOptions
.
See also:
15.11. TLS certificate authentication
The cert
auth backend allows authentication using SSL/TLS client
certificates that are either signed by a CA or self-signed.
To enable cert
authentication you need to:
-
Use SSL, see Vault Client SSL configuration
-
Configure a Java
Keystore
that contains the client certificate and the private key
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
ClientCertificateAuthenticationOptions options = ClientCertificateAuthenticationOptions.builder()
.path(…).build();
return new ClientCertificateAuthentication(options, restOperations());
}
// …
}
15.12. Cubbyhole authentication
Cubbyhole authentication uses Vault primitives to provide a secured authentication
workflow. Cubbyhole authentication uses tokens as primary login method.
An ephemeral token is used to obtain a second, login VaultToken from Vault’s
Cubbyhole secret backend. The login token is usually longer-lived and used to
interact with Vault. The login token can be retrieved either from a wrapped
response or from the data
section.
Creating a wrapped token
Response Wrapping for token creation requires Vault 0.6.0 or higher. |
$ vault token-create -wrap-ttl="10m"
Key Value
--- -----
wrapping_token: 397ccb93-ff6c-b17b-9389-380b01ca2645
wrapping_token_ttl: 0h10m0s
wrapping_token_creation_time: 2016-09-18 20:29:48.652957077 +0200 CEST
wrapped_accessor: 46b6aebb-187f-932a-26d7-4f3d86a68319
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
CubbyholeAuthenticationOptions options = CubbyholeAuthenticationOptions
.builder()
.initialToken(VaultToken.of("…"))
.wrapped()
.build();
return new CubbyholeAuthentication(options, restOperations());
}
// …
}
Using stored tokens
$ vault token create
Key Value
--- -----
token f9e30681-d46a-cdaf-aaa0-2ae0a9ad0819
token_accessor 4eee9bd9-81bb-06d6-af01-723c54a72148
token_duration 0s
token_renewable false
token_policies [root]
$ vault token create -use-limit=2 -orphan -no-default-policy -policy=none
Key Value
--- -----
token 895cb88b-aef4-0e33-ba65-d50007290780
token_accessor e84b661c-8aa8-2286-b788-f258f30c8325
token_duration 0s
token_renewable false
token_policies [none]
$ export VAULT_TOKEN=895cb88b-aef4-0e33-ba65-d50007290780
$ vault write cubbyhole/token token=f9e30681-d46a-cdaf-aaa0-2ae0a9ad0819
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
CubbyholeAuthenticationOptions options = CubbyholeAuthenticationOptions
.builder()
.initialToken(VaultToken.of("…"))
.path("cubbyhole/token")
.build();
return new CubbyholeAuthentication(options, restOperations());
}
// …
}
Remaining TTL/Renewability
Tokens retrieved from Cubbyhole associated with a non-zero TTL start their TTL at the time of token creation. That time is not necessarily identical with application startup. To compensate for the initial delay, Cubbyhole authentication performs a self lookup for tokens associated with a non-zero TTL to retrieve the remaining TTL. Cubbyhole authentication will not self-lookup wrapped tokens without a TTL because a zero TTL indicates there is no TTL associated.
Non-wrapped tokens do not provide details regarding renewability and TTL by just retrieving the token. A self-lookup will lookup renewability and the remaining TTL.
See also:
15.13. Kubernetes authentication
Vault supports since 0.8.3 kubernetes-based authentication using Kubernetes tokens.
Using Kubernetes authentication requires a Kubernetes Service Account Token,
usually mounted at /var/run/secrets/kubernetes.io/serviceaccount/token
.
The file contains the token which is read and sent to Vault.
Vault verifies its validity using Kubernetes' API during login.
Configuring Kubernetes authentication requires at least the role name to be provided:
@Configuration
class AppConfig extends AbstractVaultConfiguration {
// …
@Override
public ClientAuthentication clientAuthentication() {
KubernetesAuthenticationOptions options = KubernetesAuthenticationOptions.builder()
.role(…).jwtSupplier(…).build();
return new KubernetesAuthentication(options, restOperations());
}
// …
}
You can configure the authentication via KubernetesAuthenticationOptions
.
See also:
15.14. Authentication Steps
ClientAuthentication
objects describe the authentication flow and perform the actual
authentication steps. Pre-composed authentications are easy to use and to configure with
a tight binding to synchronous execution.
The composition of authentication methods and reusing common steps, such as posting login
payload to Vault or retrieving authentication input from an HTTP source is not intended
with ClientAuthentication
objects.
Authentication steps provide reusability of common authentication activity.
Steps created via AuthenticationSteps
describe an authentication flow in a functional
style leaving the actual authentication execution to specific executors.
AuthenticationSteps.just(VaultToken.of(…)); (1)
1 | Creates AuthenticationSteps from just a VaultToken . |
A single-step authentication flow can be created from a single input. Flows declaring
multiple authentication steps start with a Supplier
or HttpRequest
that provide an
authentication state object which can be used to map or post to Vault for login.
AuthenticationSteps.fromSupplier( (1)
() -> getAppRoleLogin(options.getRoleId(), options.getSecretId())) (2)
.login("auth/{mount}/login", options.getPath()); (3)
1 | Start declaring AuthenticationSteps accepting a Supplier<T> .
The state object type depends on the Supplier response type which can be mapped in a later step. |
2 | The actual Supplier implementation.
Creating a Map in this case. |
3 | Perform a Vault login by posting the state object (Map ) to a Vault endpoint for Vault token creation.
Note that template variables are subject to URL escaping. |
Authentication flows require an executor to perform the actual login. We provide two executors for different execution models:
-
AuthenticationStepsExecutor
as a drop-in replacement for synchronousClientAuthentication
. -
AuthenticationStepsOperator
for reactive execution.
Many ClientAuthentication
's come with static factory methods to create AuthenticationSteps
for their authentication-specific options:
AuthenticationSteps
executionCubbyholeAuthenticationOptions options = …
RestOperations restOperations = …
AuthenticationSteps steps = CubbyholeAuthentication.createAuthenticationSteps(options);
AuthenticationStepsExecutor executor = new AuthenticationStepsExecutor(steps, restOperations);
VaultToken token = executor.login();
15.15. Token Lifecycle
Vault’s tokens can be associated with a time to live. Tokens obtained by an authentication method are intended to be used as long as the session is active and should not expire while the application is active.
Spring Vault provides with LifecycleAwareSessionManager
a session manager that can renew the token until it reaches its terminal TTL to then perform another login to obtain the next token which is associated with the session.
Depending on the authentication method, a login can create two kinds of tokens:
-
VaultToken
: Generic token encapsulating the actual token. -
LoginToken
: Token associated with renewability/TTL.
Authentication methods such as TokenAuthentication
just create a VaultToken
which does not carry any renewability/TTL details. LifecycleAwareSessionManager
will run a self-lookup on the token to retrieve renewability and TTL from Vault.
VaultToken
are renewed periodically if self-lookup is enabled. Note that VaultToken
are never revoked, only LoginToken
are revoked.
Authentication methods creating LoginToken
directly (all login-based authentication methods) already provide all necessary details to setup token renewal. Tokens obtained from a login are revoked by LifecycleAwareSessionManager
if the session manager is shut down.
16. Miscellaneous
Learn in this chapter about details worth mentioning like the Spring Security integration.
16.1. Spring Security
Spring Vault integrates with Spring Security by providing implementations for BytesKeyGenerator
and BytesEncryptor
. Both implementations use Vault’s transit
backend.
VaultBytesKeyGenerator
exampleVaultOperations operations = …;
VaultBytesKeyGenerator generator = new VaultBytesKeyGenerator(operations);
byte[] key = generator.generateKey();
VaultBytesEncryptor
exampleVaultTransitOperations transit = …;
VaultBytesEncryptor encryptor = new VaultBytesEncryptor(transit, "my-key-name");
byte[] ciphertext = encryptor.encrypt(plaintext);
byte[] result = encryptor.decrypt(ciphertext);
Vault encapsulates an entropy source that is decoupled from your JVM along with server-side key-management. This relieves the burden of proper encryption/decryption from application developers and pushes the burden onto the operators of Vault. Operators of Vault commonly include the security team at an organization, which means they can ensure that data is encrypted/decrypted properly. Additionally, since encrypt/decrypt operations must enter the audit log, any decryption event is recorded.
The backend also supports key rotation, which allows a new version of the named key to be generated. All data encrypted with the key will use the newest version of the key; previously encrypted data can be decrypted using old versions of the key. Administrators can control which previous versions of a key are available for decryption, to prevent an attacker gaining an old copy of ciphertext to be able to successfully decrypt it.
Vault is after all a networked service that incurs each operation with a latency. Components heavily using encryption or random bytes generation may experience a difference in throughput and performance.