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. See JWS and JWT policies overview for a detailed introduction.

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. See the video above for a complete example, including how to make a request to the policy.

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>
    <OutputVariable>jwt-variable</OutputVariable>
</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. See the video above for a complete example, including how to make a request to the policy.

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>
    <OutputVariable>jwt-variable</OutputVariable>
</GenerateJWT>

Setting the key elements

The elements that you use to specify the key used to generate the JWT depend on the chosen algorithm, as shown in the following table:

Algorithm Key elements
HS{256/384/512}*
<SecretKey>
  <Value ref="private.secretkey"/>
  <Id>1918290</Id>
</SecretKey>
RS/PS/ES{256/384/512}*
<PrivateKey>
  <Value ref="private.privatekey"/>
  <Password ref="private.privatekey-password"/>
  <Id ref="private.privatekey-id"/>
</PrivateKey>

The <Password> and <Id> elements are optional.

*For more on the key requirments, see About signature encryption algorithms.

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>algorithm-here</Algorithm>

Specifies the encryption algorithm to sign the token.

Default N/A
Presence Required
Type String
Valid values HS256, HS384, HS512, RS256, RS384, RS512, ES256, ES384, ES512, PS256, PS384, PS512

<Audience>

<Audience>audience-here</Audience>

or:

<Audience ref='variable_containing_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>

or:

<AdditionalClaims ref='claim_payload'/>

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 attributes:

  • 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.

When you include the <Claim> element, the claim names are set statically when you configure the policy. Alternatively, you can pass a JSON object to specify the claim names. Because the JSON object is passed as a variable, the claim names in the generated JWT are determined at runtime.

For example:

<AdditionalClaims ref='json_claims'/>

Where the variable json_claims contains a JSON object in the form:

{
  "sub" : "person@example.com",
  "iss" : "urn://secure-issuer@example.com",
  "non-registered-claim" : {
    "This-is-a-thing" : 817,
    "https://example.com/foobar" : { "p": 42, "q": false }
  }
}

The generated JWT includes all of the claims in the JSON object.

<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 attributes:

  • 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.

<CriticalHeaders>

<CriticalHeaders>a,b,c</CriticalHeaders>

or:

<CriticalHeaders ref=’variable_containing_headers’/>

Adds the critical header, crit, to the JWT header. The crit header is an array of header names that must be known and recognized by the JWT receiver. For example:

{
  “typ: “...”,
  “alg” : “...”,
  “crit” : [ “a”, “b”, “c” ],
}

At runtime, the VerifyJWT policy examines the crit header. For each item listed in the crit header, it checks that the <KnownHeaders> element of the VerifyJWT policy also lists that header. Any header that the VerifyJWT policy finds in crit that is not also listed in <KnownHeaders> causes the VerifyJWT policy to fail.

Default N/A
Presence Optional
Type Comma separated array of strings
Valid values Either an array or the name of a variable containing the array.

<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 milliseconds, 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:

  • ms = milliseconds (default)
  • s = seconds
  • m = minutes
  • h = hours
  • d = days

For example, an ExpiresIn=10d is equivalent to an ExpiresIn of 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 jws.POLICYNAME.generated_jwt.

Default jws.POLICYNAME.generated_jwt
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. Use only when the algorithm is one of RS256/RS384/RS512, PS256/PS384/PS512, or ES256/ES384/ES512.

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 only when the algorithm is one of RS256/RS384/RS512, PS256/PS384/PS512, or ES256/ES384/ES512.

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 only when the algorithm is one of RS256/RS384/RS512, PS256/PS384/PS512, or ES256/ES384/ES512.

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. Use only when the algorithm is one of HS256/HS384/HS512.

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.

Edge enforces a minimum key strength for the HS256/HS384/HS512 algorithms. The minimum key length for HS256 is 32 bytes, for HS384 it is 48 bytes, and for HS512 it is 64 bytes. Using a lower-strength key causes a runtime error.

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

The Generate JWT policy does not set flow variables.

Error reference

This 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
steps.jwt.AlgorithmInTokenNotPresentInConfiguration 401 Occurs when the verification policy has multiple algorithms.
steps.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.
steps.jwt.FailedToDecode 401 The policy was unable to decode the JWT. The JWT is possibly corrupted.
steps.jwt.GenerationFailed 401 The policy was unable to generate the JWT.
steps.jwt.InsufficientKeyLength 401 For a key less than 32 bytes for the HS256 algorithm, less than 48 bytes for the HS386 algortithm, and less than 64 bytes for the HS512 algorithm.
steps.jwt.InvalidClaim 401 For a missing claim or claim mismatch, or a missing header or header mismatch.
steps.jwt.InvalidCurve 401 The curve specified by the key is not valid for the Elliptic Curve algorithm.
steps.jwt.InvalidJsonFormat 401 Invalid JSON found in the header or payload.
steps.jwt.InvalidToken 401 This error occurs when the JWT signature verification fails.
steps.jwt.JwtAudienceMismatch 401 The audience claim failed on token verification.
steps.jwt.JwtIssuerMismatch 401 The issuer claim failed on token verification.
steps.jwt.JwtSubjectMismatch 401 The subject claim failed on token verification.
steps.jwt.KeyIdMissing 401 The Verify policy uses a JWKS as a source for public keys, but the signed JWT does not include a kid property in the header.
steps.jwt.KeyParsingFailed 401 The public key could not be parsed from the given key information.
steps.jwt.NoAlgorithmFoundInHeader 401 Occurs when the JWT contains no algorithm header.
steps.jwt.NoMatchingPublicKey 401 The Verify policy uses a JWKS as a source for public keys, but the kid in the signed JWT is not listed in the JWKS.
steps.jwt.SigningFailed 401 In GenerateJWT, for a key less than the minimum size for the HS384 or HS512 algorithms
steps.jwt.TokenExpired 401 The policy attempts to verify an expired token.
steps.jwt.TokenNotYetValid 401 The token is not yet valid.
steps.jws.UnhandledCriticalHeader 401 A header found by the Verify JWT policy in the crit header is not listed in KnownHeaders.
steps.jwt.UnknownException 401 An unknown exception occurred.
steps.jwt.WrongKeyType 401 Wrong type of key specified. For example, if you specify an RSA key for an Elliptic Curve algorithm, or a curve key for an RSA algorithm.

Deployment errors

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

Error name Cause Fix
InvalidNameForAdditionalClaim The deployment will fail if the claim used in the child element <Claim> of the <AdditionalClaims> element is one of the following registered names: kid, iss, sub, aud, iat, exp, nbf, or jti. build
InvalidTypeForAdditionalClaim If the claim used in the child element <Claim> of the <AdditionalClaims> element is not of type string, number, boolean, or map, the deployment will fail. build
MissingNameForAdditionalClaim If the name of the claim is not specified in the child element <Claim> of the <AdditionalClaims> element, the deployment will fail. build
InvalidNameForAdditionalHeader This error ccurs when the name of the claim used in the child element <Claim> of the <AdditionalClaims> element is either alg or typ. build
InvalidTypeForAdditionalHeader If the type of claim used in the child element <Claim> of the <AdditionalClaims> element is not of type string, number, boolean, or map, the deployment will fail. build
InvalidValueOfArrayAttribute This error occurs when the value of the array attribute in the child element <Claim> of the <AdditionalClaims> element is not set to true or false. build
InvalidConfigurationForActionAndAlgorithm If the <PrivateKey> element is used with HS Family algorithms or the <SecretKey> element is used with RSA Family algorithms, the deployment will fail. build
InvalidValueForElement If the value specified in the <Algorithm> element is not a supported value, the deployment will fail. build
MissingConfigurationElement This error will occur if the <PrivateKey> element is not used with RSA family algorithms or the <SecretKey> element is not used with HS Family algorithms. build
InvalidKeyConfiguration If the child element <Value> is not defined in the <PrivateKey> or <SecretKey> elements, the deployment will fail. build
EmptyElementForKeyConfiguration If the ref attribute of the child element <Value> of the <PrivateKey> or <SecretKey> elements is empty or unspecified, the deployment will fail. build
InvalidVariableNameForSecret This error occurs if the flow variable name specified in the ref attribute of the child element <Value> of the <PrivateKey> or <SecretKey> elements does not contain the private prefix (private.). build
InvalidSecretInConfig This error occurs if the child element <Value> of the <PrivateKey> or <SecretKey> elements does not contain the private prefix (private.). build
InvalidTimeFormat If the value specified in the<NotBefore> element does not use a supported format, the deployment will fail. build

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.failed All JWT policies set the same variable in the case of a failure. JWT.failed = true

Example error response

JWT Policy Fault Codes

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.failed=true</Condition>
        </FaultRule>
    </FaultRules>