Ticket-Granting Ticket REST Protocol
Ticket-granting tickets can be issued by the REST protocol:
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POST /cas/v1/tickets HTTP/1.0
'Content-type': 'Application/x-www-form-urlencoded'
username=battags&password=password&additionalParam1=paramvalue
You may also specify a service parameter to verify whether the
authenticated user may be allowed to access the given service.
Successful Response
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201 Created
Location: http://www.whatever.com/cas/v1/tickets/{TGT id}
Remember that REST is stateless. Since the caller is the recipient of the ticket-granting ticket that represents a single sign-on session, that means the caller is also responsible for managing and creating single sign-on sessions, removing that responsibility from CAS. In other words, the REST protocol allows one to use CAS as an authentication engine, and not a single sign-on provider. There have been many workarounds, modifications and hacks over the years to bypass this barrier and have REST calls to also, somehow, create the necessary cookies, flows and interactions and whatever else necessary to allow applications to leverage a single sign-on session established via REST. Needless to say, all such endeavors over time have resulted in maintenance headaches, premature aging and loss of DNA.
Unsuccessful Response
If incorrect credentials are sent, CAS will respond with a 401 Unauthorized. A 400 Bad Request error
will be sent for missing parameters, etc. If you send a media type it does not
understand, it will send the 415 Unsupported Media Type.
JWT Ticket Granting Tickets
Ticket-granting tickets created by the REST protocol may be issued as JWTs instead. Support is enabled by including the following in your overlay:
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<dependency>
<groupId>org.apereo.cas</groupId>
<artifactId>cas-server-support-rest-tokens</artifactId>
<version>${cas.version}</version>
</dependency>
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implementation "org.apereo.cas:cas-server-support-rest-tokens:${project.'cas.version'}"
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dependencyManagement {
imports {
mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
}
}
dependencies {
implementation "org.apereo.cas:cas-server-support-rest-tokens"
}
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dependencies {
/*
The following platform references should be included automatically and are listed here for reference only.
implementation enforcedPlatform("org.apereo.cas:cas-server-support-bom:${project.'cas.version'}")
implementation platform(org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES)
*/
implementation "org.apereo.cas:cas-server-support-rest-tokens"
}
To request a ticket-granting ticket as JWT next, ensure the POST request matches the following:
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POST /cas/v1/tickets HTTP/1.0
username=battags&password=password&token=true&additionalParam1=paramvalue
The token parameter may either be passed as a request parameter or a request
header. The body of the response will include the ticket-granting ticket as
a JWT. Note that JWTs created are typically signed and encrypted by default with pre-generated keys.
The following settings and properties are available from the CAS configuration catalog:
cas.authn.token.crypto.encryption.key=
The encryption key is a JWT whose length is defined by the encryption key size setting. This setting supports the Spring Expression Language.
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cas.authn.token.crypto.signing.key=
The signing key is a JWT whose length is defined by the signing key size setting. This setting supports the Spring Expression Language.
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cas.authn.token.crypto.alg=
The signing/encryption algorithm to use.
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cas.authn.token.crypto.enabled=true
Whether crypto operations are enabled.
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cas.authn.token.crypto.encryption-enabled=true
Whether crypto encryption operations are enabled.
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cas.authn.token.crypto.encryption.key-size=512
The encryption key size.
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cas.authn.token.crypto.signing-enabled=true
Whether crypto signing operations are enabled.
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cas.authn.token.crypto.signing.key-size=512
The signing key size.
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cas.authn.token.crypto.strategy-type=ENCRYPT_AND_SIGN
Control the cipher sequence of operations. The accepted values are:
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cas.authn.token.webflow.enabled=true
Whether webflow auto-configuration should be enabled.
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cas.authn.token.webflow.order=0
The order in which the webflow is configured.
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cas.authn.token.credential-criteria=
A number of authentication handlers are allowed to determine whether they can operate on the provided credential and as such lend themselves to be tried and tested during the authentication handler selection phase. The credential criteria may be one of the following options:
This settings supports regular expression patterns. [?].
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cas.authn.token.name=
Name of the authentication handler.
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cas.authn.token.order=
Order of the authentication handler in the chain.
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cas.authn.token.sso-token-enabled=false
When set to true, will generate a token and store it as an authentication attribute into the single sign-on session. This token can be used later on for token-based authentication attempts, and should allow SSO access to the server.
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cas.authn.token.state=
Define the scope and state of this authentication handler and the lifecycle in which it can be invoked or activated. Available values are as follows:
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cas.authn.token.crypto.encryption.key=
The encryption key is a JWT whose length is defined by the encryption key size setting. This setting supports the Spring Expression Language.
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cas.authn.token.crypto.signing.key=
The signing key is a JWT whose length is defined by the signing key size setting. This setting supports the Spring Expression Language.
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cas.authn.token.crypto.alg=
The signing/encryption algorithm to use.
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cas.authn.token.crypto.enabled=true
Whether crypto operations are enabled.
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cas.authn.token.crypto.encryption-enabled=true
Whether crypto encryption operations are enabled.
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cas.authn.token.crypto.encryption.key-size=512
The encryption key size.
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cas.authn.token.crypto.signing-enabled=true
Whether crypto signing operations are enabled.
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cas.authn.token.crypto.signing.key-size=512
The signing key size.
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cas.authn.token.crypto.strategy-type=ENCRYPT_AND_SIGN
Control the cipher sequence of operations. The accepted values are:
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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.
Certain authentication handlers are allowed to determine whether they can operate on the provided credential and as such lend themselves to be tried and tested during the authentication handler selection phase. The credential criteria may be one of the following options:
- A regular expression pattern that is tested against the credential identifier.
- A fully qualified class name of your own design that looks similar to the below example:
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import java.util.function.Predicate;
import org.apereo.cas.authentication.Credential;
public class PredicateExample implements Predicate<Credential> {
@Override
public boolean test(final Credential credential) {
// Examine the credential and return true/false
}
}
- Path to an external Groovy script that looks similar to the below example:
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import org.apereo.cas.authentication.Credential
import java.util.function.Predicate
class PredicateExample implements Predicate<Credential> {
@Override
boolean test(final Credential credential) {
// test and return result
}
}
To prepare CAS to support and integrate with Apache Groovy, please review this guide.
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.
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, specially 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.
X509 Authentication
The feature extends the CAS REST API communication model to non-interactive X.509 authentication where REST credentials may be retrieved from a certificate embedded in the request rather than the usual and default username/password.
This pattern may be of interest in cases where the internal network architecture hides the CAS server from external users behind firewall, reverse proxy, or a messaging bus and allows only trusted applications to connect directly to the CAS server.
Usage Warning!The X.509 feature over REST using a body parameter or a http header provides a tremendously convenient target for claiming user identities or obtaining TGTs without proof of private key ownership. To securely use this feature, network configuration MUST allow connections to the CAS server only from trusted hosts which in turn have strict security limitations and logging. It is also recommended to make sure that the body parameter or the http header can only come from trusted hosts and not from the original authenticating client.
It is also possible to let the servlet container validate the TLS client key / X.509 certificate during TLS handshake, and have CAS server retrieve the certificate from the container.
Support is enabled by including the following in your overlay:
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<dependency>
<groupId>org.apereo.cas</groupId>
<artifactId>cas-server-support-rest-x509</artifactId>
<version>${cas.version}</version>
</dependency>
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implementation "org.apereo.cas:cas-server-support-rest-x509:${project.'cas.version'}"
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dependencyManagement {
imports {
mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
}
}
dependencies {
implementation "org.apereo.cas:cas-server-support-rest-x509"
}
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dependencies {
/*
The following platform references should be included automatically and are listed here for reference only.
implementation enforcedPlatform("org.apereo.cas:cas-server-support-bom:${project.'cas.version'}")
implementation platform(org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES)
*/
implementation "org.apereo.cas:cas-server-support-rest-x509"
}
The following settings and properties are available from the CAS configuration catalog:
cas.rest.x509.body-auth=false
Flag that enables
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cas.rest.x509.header-auth=true
Flag that enables
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cas.rest.x509.tls-client-auth=false
Flag that enables TLS client
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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.
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, specially 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.
Body Parameter
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POST /cas/v1/tickets HTTP/1.0
cert=<ascii certificate>