Decodes a JWT without verifying the signature on the JWT. This is most useful when used in concert with the Verify JWT Policy, when the value of a claim from within the JWT must be known before verifying the signature of the JWT.
The JWT Decode policy works regardless of the algorithm that was used to sign the JWT.
Watch a short video to learn how to decode a JWT.
Sample: Decode a JWT
The policy shown below decodes a JWT found in the flow variable var.jwt. This variable must be present and contain a viable (decodable) JWT. The policy can obtain the JWT from any flow variable.
<DecodeJWT name="JWT-Decode-HS256"> <DisplayName>JWT Verify HS256</DisplayName> <Source>var.jwt</Source> <IgnoreUnresolvedVariables>false</IgnoreUnresolvedVariables> </DecodeJWT>
Element reference for Decode JWT
The policy reference describes the elements and attributes of the Decode JWT policy.
Attributes that apply to the top-level element
<DecodeJWT name="JWT" continueOnError="false" enabled="true" async="false">
The following attributes are common to all policy parent elements.
The internal name of the policy. Characters you can use in the name are restricted to:
Optionally, use the
|async||This attribute is deprecated.||false||Deprecated|
<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.|
If present, specifies the flow variable in which the policy expects to find the JWT to decode.
Important Note: By default, the JWT is retrieved from the variable request.header.authorization. In this case, Edge looks for the JWT in the request Authorization header. If you pass the JWT in the Authorization header, you do not need to include the Source element in the policy; however, you must include Bearer in the auth header. For example, you would pass the JWT in the Authorization header like this:
curl -v http://220.127.116.11:9001/doctest-jwt/verify-rs256 -H "Authorization: Bearer <your JWT>"
You can configure to policy to retrieve the JWT from a form or query parameter variable or any other variable. If the variable does not exist or if the policy otherwise can't find the JWT, the policy returns an error.
|Valid values||An Edge flow variable name|
Upon success, the Verify JWT and Decode JWT policies set context variables according to this pattern:
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:
||The signing algorithm used on the JWT. For example, RS256, HS384, and so on.|
||The JWT subject claim.|
||The JWT issuer claim.|
||The JWT audience claim. This value may be a string, or an array of strings.|
||The expiration date/time, expressed in seconds since epoch.|
||The expiration date/time, formatted as a human-readable string. Example: 2017-09-28T21:30:45.000+0000|
||The number of seconds before the token will expire. If the token is expired, this number will be negative.|
||The time remaining before the token will expire, formatted as a human-readable string. Example: 00:59:59.926|
||true or false|
||The Date the token was issued, expressed in seconds since epoch.|
||If the JWT includes a nbf claim, this variable will contain the value. This is expressed in seconds since epoch.|
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.
||The value of the named claim (standard or additional). One of these will be set for every claim in the token.|
||The value of the named header (standard or additional). One of these will be set for every additional header in the token.|
||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.|
||Will be set to
||An array of claims supported by the JWT.|
Contains the payload in JSON format.
||Contains the header in JSON format.|
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.
These errors can occur when the policy executes.
|Fault code||HTTP status||Cause||Fix|
||401||Occurs when the policy is unable to decode the JWT. The JWT may be malformed, invalid or otherwise not decodable.||build|
||401||Occurs when the flow variable specified in the
These errors can occur when you deploy a proxy containing this policy.
||Occurs when the flow variable containing the JWT to be decoded is not specified in the
These variables are set when a runtime error occurs. For more information, see What you need to know about policy errors.
||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.||
||policy_name is the user-specified name of the policy that threw the fault.||
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