Amazon S3 - SAML2 Metadata Management

Metadata documents may also be stored in and fetched from an Amazon S3 instance. This may specially be used to avoid copying metadata files across CAS nodes in a cluster, particularly where one needs to deal with more than a few bilateral SAML integrations. Metadata documents are stored in and fetched from a single pre-defined bucket that is taught to CAS via settings.

Support is enabled by including the following module in the overlay:

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<dependency>
    <groupId>org.apereo.cas</groupId>
    <artifactId>cas-server-support-saml-idp-metadata-aws-s3</artifactId>
    <version>${cas.version}</version>
</dependency>
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implementation "org.apereo.cas:cas-server-support-saml-idp-metadata-aws-s3:${project.'cas.version'}"
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dependencyManagement {
    imports {
        mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
    }
}

dependencies {
    implementation "org.apereo.cas:cas-server-support-saml-idp-metadata-aws-s3"
}
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dependencies {
    /*
        The following platform references are included automatically and are listed for reference only.

        implementation enforcedPlatform("org.apereo.cas:cas-server-support-bom:${project.'cas.version'}")
        implementation platform(org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES)
        
    */
    implementation "org.apereo.cas:cas-server-support-saml-idp-metadata-aws-s3"
}

SAML service definitions must then be designed as follows to allow CAS to fetch metadata documents from Amazon S3 buckets:

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{
  "@class" : "org.apereo.cas.support.saml.services.SamlRegisteredService",
  "serviceId" : "the-entity-id-of-the-sp(s)",
  "name" : "SAMLService",
  "id" : 10000003,
  "description" : "Amazon S3-based metadata resolver",
  "metadataLocation" : "awss3://"
}

The following parameters are expected for the Amazon S3 object metadata:

Parameter Description
signature The metadata signing certificate, if any.
:information_source: Metadata Location

The metadata location in the registration record above needs to be specified as awss3:// to signal to CAS that SAML metadata for registered service provider must be fetched from Amazon S3 defined in CAS configuration.

The following settings and properties are available from the CAS configuration catalog:

cas.authn.saml-idp.metadata.amazon-s3.credential-access-keyUse access-key provided by AWS to authenticate.
no default
RequiredSpEL

Use access-key provided by AWS to authenticate.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.amazon-s3.credential-secret-keyUse secret key provided by AWS to authenticate.
no default
RequiredSpEL

Use secret key provided by AWS to authenticate.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.amazon-s3.crypto.encryption.keyThe encryption key is a string whose length is defined by the encryption key size setting.
no default
RequiredSpEL

The encryption key is a string whose length is defined by the encryption key size setting.

Type
String
Default
none
Defined by
EncryptionJwtCryptoProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.amazon-s3.crypto.signing.keyThe signing key is a string whose length is defined by the signing key size setting.
no default
RequiredSpEL

The signing key is a string whose length is defined by the signing key size setting.

Type
String
Default
none
Defined by
SigningJwtCryptoProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.amazon-s3.endpointAWS custom endpoint.
no default
Required

AWS custom endpoint.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.regionAWS region used.
no default
Required

AWS region used.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.bucket-nameS3 bucket that contains metadata files.
no default
SpEL

S3 bucket that contains metadata files.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.amazon-s3.client-execution-timeoutClient execution timeout.
10000
Duration

Client execution timeout.

Type
String
Default
10000
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.connection-timeoutConnection timeout.
5000
Duration

Connection timeout.

Type
String
Default
5000
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.crypto.algThe signing/encryption algorithm to use.
no default

The signing/encryption algorithm to use.

Type
String
Default
none
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.authn.saml-idp.metadata.amazon-s3.crypto.enabledWhether crypto operations are enabled.
true

Whether crypto operations are enabled.

Type
Boolean
Default
true
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.authn.saml-idp.metadata.amazon-s3.crypto.encryption.key-sizeThe encryption key size.
512

The encryption key size.

Type
Integer
Default
512
Defined by
EncryptionJwtCryptoProperties
cas.authn.saml-idp.metadata.amazon-s3.crypto.signing.key-sizeThe signing key size.
512

The signing key size.

Type
Integer
Default
512
Defined by
SigningJwtCryptoProperties
cas.authn.saml-idp.metadata.amazon-s3.crypto.strategy-typeControl the cipher sequence of operations.
ENCRYPT_AND_SIGN
Control the cipher sequence of operations. The accepted values are:
  • ENCRYPT_AND_SIGN: Encrypt the value first, and then sign.
  • SIGN_AND_ENCRYPT: Sign the value first, and then encrypt.
Type
String
Default
ENCRYPT_AND_SIGN
Defined by
EncryptionJwtSigningJwtCryptographyProperties
cas.authn.saml-idp.metadata.amazon-s3.idp-metadata-bucket-nameThe collection name that is responsible to hold the identity provider metadata.
no default
SpEL

The collection name that is responsible to hold the identity provider metadata.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
Supports
Spring Expression Language
cas.authn.saml-idp.metadata.amazon-s3.local-addressLocal address.
no default

Local address.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.max-connectionsMaximum connections setting.
10

Maximum connections setting.

Type
Integer
Default
10
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.profile-nameProfile name to use.
no default

Profile name to use.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.profile-pathProfile path.
no default

Profile path.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.proxy-hostOptionally specifies the proxy host to connect through.
no default

Optionally specifies the proxy host to connect through.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.proxy-passwordOptionally specifies the proxy password to connect through.
no default

Optionally specifies the proxy password to connect through.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.proxy-usernameOptionally specifies the proxy username to connect through.
no default

Optionally specifies the proxy username to connect through.

Type
String
Default
none
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.retry-modeOutline the requested retry mode.
STANDARD

Outline the requested retry mode. Accepted values are STANDARD, LEGACY.

Type
String
Default
STANDARD
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.socket-timeoutSocket timeout.
5000
Duration

Socket timeout.

Type
String
Default
5000
Defined by
AmazonS3SamlMetadataProperties
cas.authn.saml-idp.metadata.amazon-s3.use-reaperFlag that indicates whether to use reaper.
false

Flag that indicates whether to use reaper.

Type
Boolean
Default
false
Defined by
AmazonS3SamlMetadataProperties

Required settings may be needed to activate or affect the feature; review them even when they have a default. Optional settings only need to be set to change a default or to turn on the behavior they control. Third party settings belong to libraries such as Spring Boot that CAS builds on; their own documentation may have more detail.

Signing & encryption

This CAS feature is able to accept signing and encryption crypto keys. In most scenarios if keys are not provided, CAS will auto-generate them. The following instructions apply if you wish to manually and beforehand create the signing and encryption keys.

Note that if you are asked to create a JWK of a certain size for the key, you are to use the following set of commands to generate the token:

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wget https://raw.githubusercontent.com/apereo/cas/master/etc/jwk-gen.jar
java -jar jwk-gen.jar -t oct -s [size]

The outcome would be similar to:

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{
  "kty": "oct",
  "kid": "...",
  "k": "..."
}

The generated value for k needs to be assigned to the relevant CAS settings. Note that keys generated via the above algorithm are processed by CAS using the Advanced Encryption Standard (AES) algorithm which is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology.


Notes on configuration

Configuration Metadata

The collection of configuration properties listed in this section are automatically generated from the CAS source and components that contain the actual field definitions, types, descriptions, modules, etc. This metadata may not always be 100% accurate, or could be lacking details and sufficient explanations.

Be Selective

This section is meant as a guide only. Do NOT copy/paste the entire collection of settings into your CAS configuration; rather pick only the properties that you need. Do NOT enable settings unless you are certain of their purpose and do NOT copy settings into your configuration only to keep them as reference. All these ideas lead to upgrade headaches, maintenance nightmares and premature aging.

YAGNI

Note that for nearly ALL use cases, declaring and configuring properties listed here is sufficient. You should NOT have to explicitly massage a CAS XML/Java/etc configuration file to design an authentication handler, create attribute release policies, etc. CAS at runtime will auto-configure all required changes for you. If you are unsure about the meaning of a given CAS setting, do NOT turn it on without hesitation. Review the codebase or better yet, ask questions to clarify the intended behavior.

Naming Convention

Property names can be specified in very relaxed terms. For instance cas.someProperty, cas.some-property, cas.some_property are all valid names. While all forms are accepted by CAS, there are certain components (in CAS and other frameworks used) whose activation at runtime is conditional on a property value, where this property is required to have been specified in CAS configuration using kebab case. This is both true for properties that are owned by CAS as well as those that might be presented to the system via an external library or framework such as Spring Boot, etc.

:information_source: Note

When possible, properties should be stored in lower-case kebab format, such as cas.property-name=value. The only possible exception to this rule is when naming actuator endpoints; The name of the actuator endpoints (i.e. ssoSessions) MUST remain in camelCase mode.

Settings and properties that are controlled by the CAS platform directly always begin with the prefix cas. All other settings are controlled and provided to CAS via other underlying frameworks and may have their own schemas and syntax. BE CAREFUL with the distinction. Unrecognized properties are rejected by CAS and/or frameworks upon which CAS depends. This means if you somehow misspell a property definition or fail to adhere to the dot-notation syntax and such, your setting is entirely refused by CAS and likely the feature it controls will never be activated in the way you intend.

Validation

Configuration properties are automatically validated on CAS startup to report issues with configuration binding, especially if defined CAS settings cannot be recognized or validated by the configuration schema. Additional validation processes are also handled via Configuration Metadata and property migrations applied automatically on startup by Spring Boot and family.

Indexed Settings

CAS settings able to accept multiple values are typically documented with an index, such as cas.some.setting[0]=value. The index [0] is meant to be incremented by the adopter to allow for distinct multiple configuration blocks.

Actuator Endpoints

The following endpoints are provided by CAS:

samlIdPRegisteredServiceMetadata
CAS endpoint4 operationsNot exposed by default
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Turn the endpoint on and expose it over the web. One entry covers every operation. By default only info, health and status are exposed.

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management.endpoint.samlIdPRegisteredServiceMetadata.access=UNRESTRICTED
management.endpoints.web.exposure.include=samlIdPRegisteredServiceMetadata

Endpoints may be mapped to other paths. For example, to serve health at healthcheck:

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management.endpoints.web.path-mapping.health=healthcheck

Identity Provider Metadata

Metadata artifacts that belong to CAS as a SAML2 identity provider may also be managed and stored via Amazon S3 buckets. Artifacts such as the metadata, signing and encryption keys, etc are kept inside a bucket that carries a JSON document with the following fields:

Field Description
id The identifier of the record.
signingCertificate The signing certificate.
signingKey The signing key.
encryptionCertificate The encryption certificate.
encryptionKey The encryption key.
appliesTo The owner of this metadata document (i.e. CAS).
metadata The metadata document.

Note that the signing and encryption keys are expected to be encrypted and signed using CAS crypto keys.

Per Service

Identity provider metadata, certificates and keys can also be defined on a per-service basis to override the global defaults. Metadata documents that would be applicable to a service definition need to be put in a special bucket named using the [service-name][service-numeric-identifier] format.