GenerateJWT policy

What

Generates a signed JWT, with a configurable set of claims. The JWT can then be returned to clients, transmitted to backend targets, or used in other ways.

Video

Watch a short video to learn how to generate a signed JWT.

Samples

Generate a JWT signed with the HS256 algorithm

This example policy generates a new JWT and signs it using the HS256 algorithm. HS256 relies on a shared secret for both signing and verifying the signature.

When this policy action is triggered, Edge encodes the JWT header and payload, then digitally signs the JWT.

The policy configuration here will create a JWT with a set of standard claims as defined by the JWT specification, including an expiry of 1 hour, as well as an additional claim. You can include as many additional claims as you wish. See the Element reference for details on the requirements and options for each element in this sample policy.

<GenerateJWT name="JWT-Generate-HS256">
    <DisplayName>JWT Generate HS256</DisplayName>
    <Algorithm>HS256</Algorithm>
    <IgnoreUnresolvedVariables>false</IgnoreUnresolvedVariables>
    <SecretKey>
        <Value ref="private.secretkey"/>
        <Id>1918290</Id>
    </SecretKey>
    <ExpiresIn>1h</ExpiresIn>
    <Subject>monty-pythons-flying-circus</Subject>
    <Issuer>urn://apigee-edge-JWT-policy-test</Issuer>
    <Audience>fans</Audience>
    <Id/>
    <AdditionalClaims>
        <Claim name="show">And now for something completely different.</Claim>
    </AdditionalClaims>
</GenerateJWT>

The resulting JWT will have this header …

{
  "typ" : "JWT", 
  "alg" : "HS256",
  "kid" : "1918290"
}

… and will have a payload with contents something like this:

{ 
  "sub" : "monty-pythons-flying-circus",
  "iss" : "urn://apigee-edge-JWT-policy-test",
  "aud" : "show",
  "iat" : 1506553019,
  "exp" : 1506556619,
  "jti" : "BD1FF263-3D25-4593-A685-5EC1326E1F37",
  "show": "And now for something completely different."
}

The value of the iat, exp, and jti claims will vary.

Generate a JWT signed with the RS256 algorithm

This example policy generates a new JWT and signs it using the RS256 algorithm. Generating an RS256 signature relies on an RSA private key, which must be provided in PEM-encoded form. When this policy action is triggered, Edge encodes and digitally signs the JWT, including the claims. To learn about the parts of a JWT and how they are encrypted and signed, refer to RFC7519.

<GenerateJWT name="JWT-Generate-RS256">
    <Algorithm>RS256</Algorithm>
    <IgnoreUnresolvedVariables>false</IgnoreUnresolvedVariables>
    <PrivateKey>
        <Value ref="private.privatekey"/>
        <Password ref="private.privatekey-password"/>
        <Id ref="private.privatekey-id"/>
    </PrivateKey>
    <Subject>apigee-seattle-hatrack-montage</Subject>
    <Issuer>urn://apigee-edge-JWT-policy-test</Issuer>
    <Audience>urn://c60511c0-12a2-473c-80fd-42528eb65a6a</Audience>
    <ExpiresIn>60m</ExpiresIn>
    <Id/>
    <AdditionalClaims>
        <Claim name="show">And now for something completely different.</Claim>
    </AdditionalClaims>
</GenerateJWT>

Element reference for Generate JWT

The policy reference describes the elements and attributes of the Generate JWT policy.

Note: Configuration will differ somewhat depending on the encryption algorithm you use. Refer to the Samples for examples that demonstrate configurations for specific use cases.

Attributes that apply to the top-level element

<GenerateJWT name="JWT" continueOnError="false" enabled="true" async="false">

The following attributes are common to all policy parent elements.

Attribute Description Default Presence
name The internal name of the policy. Characters you can use in the name are restricted to: A-Z0-9._\-$ %. However, the Edge management UI enforces additional restrictions, such as automatically removing characters that are not alphanumeric.

Optionally, use the <displayname></displayname> element to label the policy in the management UI proxy editor with a different, natural-language name.

N/A Required
continueOnError Set to false to return an error when a policy fails. This is expected behavior for most policies.

Set to true to have flow execution continue even after a policy fails.

false Optional
enabled Set to true to enforce the policy.

Set to false to "turn off" the policy. The policy will not be enforced even if it remains attached to a flow.

true Optional
async This attribute is deprecated. false Deprecated

<DisplayName>

<DisplayName>Policy Display Name</DisplayName>

Use in addition to the name attribute to label the policy in the management UI proxy editor with a different, natural-language name.

Default If you omit this element, the value of the policy's name attribute is used.
Presence Optional
Type String

<Algorithm>

<Algorithm>HS256|RS256</Algorithm>

Specifies the encryption algorithm to sign the token. RS256 employs a public/secret key pair, while HS256 employs a shared secret.

Default N/A
Presence Required
Type String
Valid values HS256, HS384, HS512, RS256, RS384, RS512

<Audience>

<Audience>audience-here</Audience>

The policy generates a JWT containing an aud claim set to the specified value. This claim identifies the recipients that the JWT is intended for. This is one of the registered claims mentioned in RFC7519.

Default N/A
Presence Optional
Type Array (a list of comma-separated values)
Valid values Anything that identifies the audience.

<AdditionalClaims/Claim>

<AdditionalClaims>
    <Claim name='claim1'>explicit-value-of-claim-here</Claim>
    <Claim name='claim2' ref='variable-name-here'/>
    <Claim name='claim3' ref='variable-name-here' type='boolean'/>
 </AdditionalClaims>

Lets you specify additional claim name/value pair(s) in the payload of the JWT. You can specify the claim explicitly as string, a number, a boolean, a map, or an array. A map is simply a set of name/value pairs.

Default N/A
Presence Optional
Valid values Any value that you want to use for an additional claim. You can specify the claim explicitly as string, a number, a boolean, a map, or an array.

The <Claim> element takes these attribues:

  • name - (Required) The name of the claim.
  • ref - (Optional) The name of a flow variable. If present, the policy will use the value of this variable as the claim. If both a ref attribute and an explicit claim value are specified, the explicit value is the default, and is used if the referenced flow variable is unresolved.
  • type - (Optional) One of: string (default), number, boolean, or map
  • array - (Optional) Set to true to indicate if the value is an array of types. Default: false.

<AdditionalHeaders/Claim>

<AdditionalHeaders>
    <Claim name='claim1'>explicit-value-of-claim-here</Claim>
    <Claim name='claim2' ref='variable-name-here'/>
    <Claim name='claim3' ref='variable-name-here' type='boolean'/>
    <Claim name='claim4' ref='variable-name' type='string' array='true'/>
 </AdditionalHeaders>

Puts the additional claim name/value pair(s) in the header for the JWT.

Default N/A
Presence Optional
Valid values Any value that you want to use for an additional claim. You can specify the claim explicitly as string, a number, a boolean, a map, or an array.

The <Claim> element takes these attribues:

  • name - (Required) The name of the claim.
  • ref - (Optional) The name of a flow variable. If present, the policy will use the value of this variable as the claim. If both a ref attribute and an explicit claim value are specified, the explicit value is the default, and is used if the referenced flow variable is unresolved.
  • type - (Optional) One of: string (default), number, boolean, or map
  • array - (Optional) Set to true to indicate if the value is an array of types. Default: false.

<CustomClaims>

Note: Currently, a CustomClaims element is inserted when you add a new GenerateJWT policy through the UI. This element is not functional and is ignored. The correct element to use instead is <AdditionalClaims>. The UI will be updated to insert the correct elements at a later time.

<ExpiresIn>

<ExpiresIn>time-value-here</ExpiresIn>

Specifies the lifespan of the JWT in seconds, minutes, hours, or days.

Default N/A
Presence Optional
Type Integer
Valid values An value or a reference to a flow variable containing the value. Time units can be specified as follows:
  • s = seconds (default)
  • m = minutes
  • h = hours
  • d = days

    For example, an ExpiresIn = 10d is equivalent to an ExpiresIn of 864000 or 864000s.

<Id>

<Id>explicit-jti-value-here</Id>
 -or-
<Id ref='variable-name-here'/>
 -or-
<Id/>

Generates a JWT with the specific jti claim. When the text value and ref attribute are both empty, the policy will generate a jti containing a random UUID. The JWT ID (jti) claim is a unique identifier for the JWT. For more information on jti, refer to RFC7519.

Default N/A
Presence Optional
Type String, or reference.
Valid values Either a string or the name of a flow variable containing the ID.

<IgnoreUnresolvedVariables>

<IgnoreUnresolvedVariables>true|false</IgnoreUnresolvedVariables>

Set to false if you want the policy to throw an error when any referenced variable specified in the policy is unresolvable. Set to true to treat any unresolvable variable as an empty string (null).

Default False
Presence Optional
Type Boolean
Valid values true or false

<Issuer>

<Issuer ref='variable-name-here'/>
<Issuer>issuer-string-here</Issuer>

The policy generates a JWT containing a claim with name iss, with a value set to the specified value. A claim that identifies the issuer of the JWT. This is one of the registered set of claims mentioned in RFC7519.

Default N/A
Presence Optional
Type String, or reference
Valid values Any

<NotBefore>

<NotBefore>2017-08-14T11:00:21-07:00</NotBefore>

Specifies an absolute time value for the token's expiration. The token will not be valid until the specified time.

Default N/A
Presence Optional
Type String
Valid values See below.

Valid time values for the NotBefore element

Name Format Example
sortable yyyy-MM-dd'T'HH:mm:ss.SSSZ 2017-08-14T11:00:21.269-0700
RFC 1123 EEE, dd MMM yyyy HH:mm:ss zzz Mon, 14 Aug 2017 11:00:21 PDT
RFC 850 EEEE, dd-MMM-yy HH:mm:ss zzz Monday, 14-Aug-17 11:00:21 PDT
ANCI-C EEE MMM d HH:mm:ss yyyy Mon Aug 14 11:00:21 2017

<OutputVariable>

<OutputVariable>jwt-variable</OutputVariable>

Specifies where to place the JWT generated by this policy. By default it is placed into the flow variable message.content.

Default message.content
Presence Optional
Type String (a flow variable name)

<PrivateKey/Id>

<PrivateKey>
  <Id ref="flow-variable-name-here"/>
</PrivateKey>

or

<PrivateKey>
  <Id>your-id-value-here</Id>
</PrivateKey>

Specifies the key ID (kid) to include in the JWT header. See also "Using a JSON Web Key Set (JWKS)" at JWT policies overview to verify a JWT.

Default N/A
Presence Optional
Type String
Valid values A flow variable or string

<PrivateKey/Password>

<PrivateKey>
  <Password ref="private.privatekey-password"/>
</PrivateKey>

Specify the password the policy should use to decrypt the private key, if necessary. Use the ref attribute to pass the key in a flow variable. Use this element only when the algorithm is an RSA variant.

Default N/A
Presence Optional
Type String
Valid values A flow variable reference.

Note: You must specify a flow variable. Edge will reject as invalid a policy configuration in which the password is specified in plaintext. The flow variable must have the prefix "private". For example, private.mypassword

<PrivateKey/Value>

<PrivateKey>
  <Value ref="private.variable-name-here"/>
</PrivateKey>

Specifies a PEM-encoded private key used to sign the JWT. Use the ref attribute to pass the key in a flow variable. Use this only with the GenerateJWT policy, when the algorithm is an RSA variant.

Default N/A
Presence Required to generate a JWT using the RS256 algorithm.
Type String
Valid values A flow variable containing a string representing a PEM-encoded RSA private key value.

Note: The flow variable must have the prefix "private". For example, private.mykey

<SecretKey/Id>

<SecretKey>
  <Id ref="flow-variable-name-here"/>
</SecretKey>

or

<SecretKey>
  <Id>your-id-value-here</Id>
</SecretKey>

Specifies the key ID (kid) to include in the JWT header of a JWT signed with an HMAC algorithm.

Default N/A
Presence Optional
Type String
Valid values A flow variable or string

<SecretKey/Value>

<SecretKey>
  <Value ref="private.your-variable-name"/>
</SecretKey>

Provides the secret key used to verify or sign tokens with an HMAC algorithm. Use only when the algorithm is one of HS256, HS384, HS512. Use the ref attribute to pass the key in a flow variable.

Default N/A
Presence Required for HMAC algorithms.
Type String
Valid values A flow variable referring to a string

Note: If a flow variable, it must have the prefix "private". For example, private.mysecret

<Subject>

<Subject>subject-string-here</Subject>
or
<Subject ref="flow_variable" />

For example:

<Subject ref="apigee.developer.email"/>

The policy generates a JWT containing a sub claim, set to the specified value.This claim identifies or makes a statement about the subject of the JWT. This is one of the standard set of claims mentioned in RFC7519.

Default N/A
Presence Optional
Type String
Valid values Any value uniquely identifying a subject or a flow variable referring to a value.

Flow variables

Upon success, the Verify JWT and Decode JWT policies set context variables according to this pattern:

jwt.{policy_name}.{variable_name}

For example, if the policy name is jwt-parse-token , then the policy will store the subject specified in the JWT to this context variable: jwt.jwt-parse-token.subject

Variable name Description
header.algorithm The signing algorithm used on the JWT. For example, RS256, HS384, and so on.
claim.subject The JWT subject claim.
claim.issuer The JWT issuer claim.
claim.audience The JWT audience claim. This value may be a string, or an array of strings.
claim.expiry The expiration date/time, expressed in seconds since epoch.
expiry_formatted The expiration date/time, formatted as a human-readable string. Example: 2017-09-28T21:30:45.000+0000
seconds_remaining The number of seconds before the token will expire. If the token is expired, this number will be negative.
time_remaining_formatted The time remaining before the token will expire, formatted as a human-readable string. Example: 00:59:59.926
is_expired true or false
claim.issuedat The Date the token was issued, expressed in seconds since epoch.
claim.notbefore If the JWT includes a nbf claim, this variable will contain the value. This is expressed in seconds since epoch.
valid In the case of VerifyJWT, this variable will be true when the signature is verified, and the current time is before the token expiry, and after the token notBefore value, if they are present. Otherwise false.

In the case of DecodeJWT, this variable is not set.

claim.name The value of the named claim (standard or additional). One of these will be set for every claim in the token.
header.name The value of the named header (standard or additional). One of these will be set for every additional header in the token.
header.kid The Key ID, if added when the JWT was generated. See also "Using a JSON Web Key Set (JWKS)" at JWT policies overview to verify a JWT.
header.type Will be set to JWT.
payload-claim-names An array of claims supported by the JWT.
payload-json
Contains the payload in JSON format.
header-json Contains the header in JSON format.

Error reference

TThis section describes the fault codes and error messages that are returned and fault variables that are set by Edge when this policy triggers an error. This information is important to know if you are developing fault rules to handle faults. To learn more, see What you need to know about policy errors and Handling faults.

Runtime errors

These errors can occur when the policy executes.

Fault code HTTP status Occurs when
policies.jwt.AlgorithmInTokenNotPresentInConfiguration Occurs when the verification policy has multiple algorithms
policies.jwt.JwtAudienceMismatch 401 The audience claim failed on token verification.
policies.jwt.AlgorithmMismatch 401 The algorithm specified in the Generate policy did not match the one expected in the Verify policy. The algorithms specified must match.
policies.jwt.JwtClaimNotPresent 401 The JWT did not contain a claim on token verification.
policies.jwt.ClaimTypeMismatch 401
policies.jwt.FailedToDecode 401 The policy was unable to decode the JWT. The JWT is possibly corrupted.
policies.jwt.InvalidJwt 401 This error occurs when the JWT signature verification fails.
policies.jwt.InvalidClaim 401
policies.jwt.JwtIssuerMismatch 401 The issuer claim failed on token verification.
policies.jwt.JwtSubjectMismatch 401 The subject claim failed on token verification.
policies.jwt.KeyIdMissing
policies.jwt.KeyParsingFailed
policies.jwt.NoAlgorithmFoundInToken Occurs when the verification policy has multiple algorithms.
policies.jwt.NoMatchingPublicKey From JWKS.
policies.jwt.TokenExpired 401 The policy attempts to verify an expired token.

Deployment errors

These errors can occur when you deploy a proxy containing this policy.

Error name Occurs when
InvalidJwtAlgorithm The only valid values are: RS256, RS384, RS512, HS256, HS384, and HS512.
InvalidNameForAdditionalClaim

InvalidTypeForAdditionalClaim

InvalidTypeForAdditionalHeader

MissingNameForAdditionalClaim

InvalidNameForAdditionalHeader

MissingNameForAdditionalHeader

InvalidAlgorithm

InvalidConfigurationForVerify

InvalidValueOfArrayAttribute

InvalidConfigurationForActionAndAlgorithmFamily

InvalidEmptyElement

InvalidValueForElement

InvalidFamiliesForAlgorithm

MissingConfigurationElement

InvalidKeyConfiguration

MissingElementForKeyConfiguration

EmptyElementForKeyConfiguration

InvalidPublicKeyValue

InvalidVariableNameForSecret

InvalidSecretInConfig

FailedToResolveVariable

InvalidTimeFormat

InvalidPublicKeyId

Other possible deployment errors.

Fault variables

These variables are set when a runtime error occurs. For more information, see What you need to know about policy errors.

Variables Where Example
fault.name="fault_name" fault_name is the name of the fault, as listed in the Runtime errors table above. The fault name is the last part of the fault code. fault.name Matches "TokenExpired"
jwt.policy_name.failed policy_name is the user-specified name of the policy that threw the fault. jwt.JWT-Policy.failed = true

Example error response

For error handling, the best practice is to trap the errorcode part of the error response. Do not rely on the text in the faultstring, because it could change.

Example fault rule

<FaultRules>
    <FaultRule name="JWT Policy Errors">
        <Step>
            <Name>JavaScript-1</Name>
            <Condition>(fault.name Matches "TokenExpired")</Condition>
        </Step>
        <Condition>jwt.JWT-1.failed=true</Condition>
    </FaultRule>
</FaultRules>