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### What
Verifies the signature on a JWS received from clients or other systems. This policy also
extracts headers into context variables so that subsequent policies or conditions can examine
those values to make authorization or routing decisions.
See [JWS and JWT policies overview](https://docs.apigee.com/api-platform/reference/policies/jwt-policies-overview) for a detailed introduction.
If the JWS is verified and valid, then the request is
allowed to proceed. If the JWS signature cannot be verified or if the JWS is invalid because of
some type of error, all processing stops and an error is returned in the response.
To learn about the parts of a JWS and how they are encrypted and signed, refer to
[RFC7515](https://tools.ietf.org/html/rfc7515).
### Video
Watch a short video to learn how to verify the signature on a JWS. While this video is
specific to verifying a JWT, many of the concepts are the same for JWS.
## Samples
- [Verify an attached JWS signed with the HS256
algorithm](https://docs.apigee.com/api-platform/reference/policies/verify-jws-policy#verify-a-JWS-signed-with-the-hs256-algorithm)
- [Verify a detached JWS signed with the RS256
algorithm](https://docs.apigee.com/api-platform/reference/policies/verify-jws-policy#verify-a-JWS-signed-with-the-rs256-algorithm)
### Verify an attached JWS signed with the HS256
algorithm
This example policy verifies an attached JWS that was signed with the HS256 encryption algorithm, HMAC
using a SHA-256 checksum. The JWS is passed in the proxy request by using a form parameter named
`JWS`. The key is contained in a variable named `private.secretkey`.
An attached JWS contains the encoded header, payload, and signature:
```
header.payload.signature
```
The policy configuration includes the information Edge needs to decode and evaluate the JWS,
such as where to find the JWS (in a flow variable specified in the `` element),
the required signing algorithm, and where to find the secret key (stored in an Edge flow variable, which could
have been retrieved from the Edge KVM, for example).
```
JWS Verify HS256HS256request.formparam.JWSfalse
```
The policy writes its output to context variables so that subsequent policies or conditions
in the API proxy can examine those values. See [Flow variables](https://docs.apigee.com/api-platform/reference/policies/verify-jws-policy#flow-variables) for a
list of the variables set by this policy.
### Verify a detached JWS signed with the RS256
algorithm
This example policy verifies a detached JWS that was signed with the RS256 algorithm. To verify,
you need to provide the public key. The JWS is passed in the proxy request by using a form parameter
named `JWS`. The public key is contained in a variable named `public.publickey`.
A detached JWS omits the payload from the JWS:
```
header..signature
```
It is up to you to pass the payload to the VerifyJWS policy by specifying the variable name containing the payload to the
`` element. The specified content in ``
must be in the original unencoded form it was when the JWS signature was created.
```
JWS Verify RS256RS256request.formparam.JWSfalseprivate.payload
```
The policy writes its output to context variables so that subsequent policies or conditions
in the API proxy can examine those values. See [Flow variables](https://docs.apigee.com/api-platform/reference/policies/verify-jws-policy#flow-variables) for a
list of the variables set by this policy.
## Setting the key elements
The elements that you use to specify the key used to verify the JWS depend on the chosen algorithm,
as shown in the following table:
> [!NOTE]
> **Note:** The RS\*, PS\*, and ES\* algorithms all use the same elements to specify the key, but the ES\* key data is different than that used by the RS\* and PS\* algorithms. For more on the key requirements, see [About signature encryption algorithms](https://docs.apigee.com/api-platform/reference/policies/jwt-policies-overview#about-signature-encryption-algorithms).
| Algorithm | key elements |
|---|---|---|
| HS\* | ``` ``` |
| RS\*, ES\*, PS\* | ``` ``` or: ``` ``` |
| ^\*^For more on the key requirements, see [About signature encryption algorithms](https://docs.apigee.com/api-platform/reference/policies/jwt-policies-overview#about-signature-encryption-algorithms). |||
## Element reference
The policy reference describes the elements and attributes of the Verify JWS policy.
**Note:** Configuration will differ somewhat depending on the encryption
algorithm you use. Refer to the [Samples](https://docs.apigee.com/api-platform/reference/policies/verify-jws-policy#Samples) for examples that demonstrate
configurations for specific use cases.
### Attributes that apply to the
top-level element
```
```
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 `` 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 |
## \
```
Policy Display Name
```
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 |
## \
```
HS256
```
Specifies the encryption algorithm to sign the token. RS\*/PS\*/ES\* algorithms employ a public/secret key pair,
while HS\* algorithms employ a shared secret. See also [About signature encryption algorithms](https://docs.apigee.com/api-platform/reference/policies/jwt-policies-overview#about-signature-encryption-algorithms).
You can specify multiple values separated by commas. For example "HS256, HS512" or "RS256, PS256".
However, you cannot combine HS\* algorithms with any others or ES\* algorithms with any others because they
require a specific key type. You can combine RS\* and PS\* algorithms.
|---|---|
| **Default** | N/A |
| **Presence** | Required |
| **Type** | String of comma-separated values |
| **Valid values** | HS256, HS384, HS512, RS256, RS384, RS512, ES256, ES384, ES512, PS256, PS384, PS512 |
## \
```
explicit-value-of-claim-here
```
Validates that the JWS header contains the specified additional claim name/value pair(s) and that the asserted claim values match.
> [!NOTE]
> The `` element supports the dynamic string substitution feature called [message templating](https://docs.apigee.com/api-platform/reference/message-template-intro).
An additionl claim uses a name that is not one of the standard, registered JWS claim names.
The value of an additional claim can be a string, a number, a boolean, a map, or an array. A map
is simply a set of name/value pairs. The value for a claim of any of these types can be specified
explicitly in the policy configuration, or indirectly via a reference to a flow variable.
> [!NOTE]
> **Note:** Do not use any of the registered claim names in this element. The registered claims are specified in [RFC7519](https://tools.ietf.org/html/rfc7519). They include: "iss", "sub", "aud", "iat", "exp", "nbf", and "jti".
|---|---|
| **Default** | N/A |
| **Presence** | Optional |
| **Type** | String (default), number, boolean, or map. The type defaults to String if no type is specified. |
| **Array** | Set to **true** to indicate if the value is an array of types. Default: false |
| **Valid values** | Any value that you want to use for an additional claim. |
The `` element takes these attributes:
- **name** - (Required) The name of the claim.
> [!NOTE]
> **Note:** Do not use any of the registered claim names in this element. The registered claims are specified in [RFC7519](https://tools.ietf.org/html/rfc7519). They include: "iss", "sub", "aud", "iat", "exp", "nbf", and "jti".
- **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.
## \
```
variable-name-here
```
A generated JWS with a content payload is in the form:
```
header.payload.signature
```
If you use the [GenerateJWS policy](https://docs.apigee.com/api-platform/reference/policies/generate-jws-policy) to create detached payload, the generated JWS omits the payload and is
in the form:
```
header..signature
```
For a detached payload, it is up to you to pass the payload to the VerifyJWS policy by using the
`` element. The specified content payload must be in the
original unencoded form it was when the JWS signature was created.
> [!NOTE]
> Only set this element when you use the GenerateJWS policy to create a JWS with a detached content payload.
The policy throws an error when:
- `` is specified when the JWS does not contain a detached content payload (fault code is `steps.jws.ContentIsNotDetached`).
- `` is omitted and the JWS has a detached content payload (fault code is `steps.jws.InvalidSignature`).
|---|---|
| **Default** | `N/A` |
| **Presence** | Optional |
| **Type** | Variable reference |
## \
```
true|false
```
Set to false if you want the policy to throw an error when any header listed in the
**crit** header of the JWS is not listed in the `` element.
Set to true to cause the VerifyJWS policy to ignore the **crit** header.
One reason to set this element to true is if you are in a testing environment and
you do not want the policy to fail because of a missing header.
|---|---|
| **Default** | false |
| **Presence** | Optional |
| **Type** | Boolean |
| **Valid values** | true or false |
## \
```
true|false
```
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 |
## \
```
a,b,c
or:
```
The [GenerateJWS policy](https://docs.apigee.com/api-platform/reference/policies/generate-jws-policy) uses the `` element to populate the
**crit** header in a token. For example:
```
{
“typ: “...”,
“alg” : “...”,
“crit” : [ “a”, “b”, “c” ],
}
```
The VerifyJWS policy examines **crit** header in the JWS, if it exists, and for each item listed it
checks that the `` element also lists that header. The
`` element can contain a superset of the items listed in **crit** .
It is only necessary that all the headers listed in **crit** are listed in the
`` element. Any header that the policy finds in **crit**
that is not also listed in `` causes the VerifyJWS policy to fail.
You can optionally configure the VerifyJWS policy to ignore the **crit** header by
setting the `` element to `true`.
> [!NOTE]
> **Note:** The VerifyJWS policy does not actually handle or process the headers listed by the `` element. It is left for you later in the proxy or the backend to actually handle those claims.
|---|---|
| **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. |
## \
```
jwks-value-here
or:
or:
```
Specifies a value in JWKS format ([RFC 7517](https://tools.ietf.org/html/rfc7517))
containing a set of public keys. **Use only when the algorithm is one of RS256/RS384/RS512,
PS256/PS384/PS512, or ES256/ES384/ES512.**
If the inbound JWS bears a key ID which present in the set of
JWKS, then the policy will use the correct public key to verify the JWS signature. For details
about this feature, see [Using a JSON Web Key Set (JWKS) to verify a JWS](https://docs.apigee.com/api-platform/reference/policies/jwt-policies-overview#usingajsonwebkeysetjwkstoverifyaJWS).
If you fetch the value from a public URL, Edge caches the JWKS for a period of 300 seconds.
When the cache expires, Edge fetches the JWKS again.
> [!NOTE]
> **Note:** If the public URL that returns the JWKS is configured to support SNI clients, Edge for Private Cloud users must enable SNI on the Message Processors. SNI is not enabled by default for Private Cloud installations. See [Supporting SNI for requests from Edge to the backend](https://docs.apigee.com/api-platform/system-administration/using-sni-edge#supportingsniforrequestsfromedgetothebackend) for more.
|---|---|
| **Default** | N/A |
| **Presence** | To verify a JWS using an RSA algorithm, you must either either use the JWKS or Value element. |
| **Type** | String |
| **Valid values** | A flow variable, string value, or URL. |
## \
```
-or-
---BEGIN PUBLIC KEY---
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAw2kPrRzcufvUNHvTH/WW
Q0UrCw5c0+Y707KX3PpXkZGbtTT4nvU1jC0d1lHV8MfUyRXmpmnNxJHAC2F73IyN
C5TBtXMORc+us7A2cTtC4gZV256bT4h3sIEMsDl0Joz9K9MPzVPFxa1i0RgNt06n
Xn/Bs2UbbLlKP5Q1HPxewUDEh0gVMqz9wdIGwH1pPxKvd3NltYGfPsUQovlof3l2
ALvO7i5Yrm96kknfFEWf1EjmCCKvz2vjVbBb6mp1ZpYfc9MOTZVpQcXSbzb/BWUo
ZmkDb/DRW5onclGzxQITBFP3S6JXd4LNESJcTp705ec1cQ9Wp2Kl+nKrKyv1E5Xx
DQIDAQAB
---END PUBLIC KEY---
```
Specifies the public key used to verify the signature on the JWS. Use the ref attribute to
pass the key in a flow variable, or specify the PEM-encoded key directly. **Use only when the
algorithm is one of RS256/RS384/RS512, PS256/PS384/PS512, or ES256/ES384/ES512.**
|---|---|
| **Default** | N/A |
| **Presence** | To verify a JWS signed with an RSA algorithm, you must either either use the JWKS or Value elements. |
| **Type** | String |
| **Valid values** | A flow variable or string. |
## \
```
```
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` |
## \
```
JWS-variable
```
If present, specifies the flow variable in which the policy expects to find the JWS to
verify.
> [!NOTE]
> **Note:** By default, the JWS is retrieved from the variable **request.header.authorization** . In this case, Edge looks for the JWS in the request Authorization header. If you pass the JWS 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 JWS in the Authorization header like this:
>
> ```
> curl -v http://52.200.92.187:9001/doctest-JWS/verify-rs256 -H "Authorization: Bearer "
> ```
>
> You can configure to policy to retrieve the JWS 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
> JWS, the policy returns an error.
|---|---|
| **Default** | `request.header.authorization` (See the note above for important information about the default). |
| **Presence** | Optional |
| **Type** | String |
| **Valid values** | An Edge flow variable name. |
## Flow variables
Upon success, the **Verify JWS** and **Decode JWS** policies set
context variables according to this pattern:
```
jws.{policy_name}.{variable_name}
```
For example, if the policy name is `verify-jws`, then the policy will store
the algorithm specified in the JWS to this context variable:
`jws.verify-jws.header.algorithm`
| Variable name | Description |
|---|---|
| `decoded.header.name` | The JSON-parsable value of a header in the payload. One variable is set for every header in the payload. While you can also use the `header.name` flow variables, this is the recommended variable to use to access a header. |
| `header.algorithm` | The signing algorithm used on the JWS. For example, RS256, HS384, and so on. See [(Algorithm) Header Parameter](https://tools.ietf.org/html/rfc7515#section-4.1.1) for more. |
| `header.kid` | The Key ID, if added when the JWS was generated. See also "Using a JSON Web Key Set (JWKS)" at [JWT and JWS policies overview](https://docs.apigee.com/api-platform/reference/policies/jwt-policies-overview) to verify a JWS. See [(Key ID) Header Parameter](https://tools.ietf.org/html/rfc7515#section-4.1.4) for more. |
| `header.type` | The header type value. See [(Type) Header Parameter](https://tools.ietf.org/html/rfc7515#section-4.1.9) for more. |
| `header.name` | The value of the named header (standard or additional). One of these will be set for every additional header in the header portion of the JWS. |
| `header-json` | The header in JSON format. |
| `payload` | The JWS payload if the JWS has an attached payload. For a detached payload, this variable is empty. |
| `valid` | In the case of VerifyJWS, 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 DecodeJWS, this variable is not set. |
## 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](https://docs.apigee.com/api-platform/fundamentals/what-you-need-know-about-policy-errors) and [Handling
faults](https://docs.apigee.com/api-platform/fundamentals/fault-handling).
### Runtime errors
These errors can occur when the policy executes.
> [!IMPORTANT]
> **Tip:** Use [API Monitoring](https://docs.apigee.com/api-monitoring) to investigate fault codes and diagnose issues faster. See [Set up a policy fault code alert](https://docs.apigee.com/api-monitoring/alerts-notifications#fault-code-alert) for an example. See [Fault code reference](https://docs.apigee.com/api-monitoring/fault-codes) for a complete list of all fault codes that you can handle with API Monitoring.
| Fault code | HTTP status | Occurs when |
|---|---|---|
| `steps.jws.AlgorithmInTokenNotPresentInConfiguration` | 401 | Occurs when the verification policy has multiple algorithms |
| `steps.jws.AlgorithmMismatch` | 401 | The algorithm specified in the header by the Generate policy did not match the one expected in the Verify policy. The algorithms specified must match. |
| `steps.jws.ContentIsNotDetached` | 401 | `` is specified when the JWS does not contain a detached content payload. |
| `steps.jws.FailedToDecode` | 401 | The policy was unable to decode the JWS. The JWS is possibly corrupted. |
| `steps.jws.InsufficientKeyLength` | 401 | For a key less than 32 bytes for the HS256 algorithm |
| `steps.jws.InvalidClaim` | 401 | For a missing claim or claim mismatch, or a missing header or header mismatch. |
| `steps.jws.InvalidCurve` | 401 | The curve specified by the key is not valid for the Elliptic Curve algorithm. |
| `steps.jws.InvalidJsonFormat` | 401 | Invalid JSON found in the JWS header. |
| `steps.jws.InvalidJws` | 401 | This error occurs when the JWS signature verification fails. |
| `steps.jws.InvalidPayload` | 401 | The JWS payload is invalid. |
| `steps.jws.InvalidSignature` | 401 | `` is omitted and the JWS has a detached content payload. |
| `steps.jws.KeyIdMissing` | 401 | The Verify policy uses a JWKS as a source for public keys, but the signed JWS does not include a `kid` property in the header. |
| `steps.jws.KeyParsingFailed` | 401 | The public key could not be parsed from the given key information. |
| `steps.jws.MissingPayload` | 401 | The JWS payload is missing. |
| `steps.jws.NoAlgorithmFoundInHeader` | 401 | Occurs when the JWS omits the algorithm header. |
| `steps.jws.NoMatchingPublicKey` | 401 | The Verify policy uses a JWKS as a source for public keys, but the `kid` in the signed JWS is not listed in the JWKS. |
| `steps.jws.UnhandledCriticalHeader` | 401 | A header found by the Verify JWS policy in the `crit` header is not listed in `KnownHeaders`. |
| `steps.jws.UnknownException` | 401 | An unknown exception occurred. |
| `steps.jws.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 | Occurs when |
|---|---|
| `InvalidAlgorithm` | The only valid values are: RS256, RS384, RS512, PS256, PS384, PS512, ES256, ES384, ES512, HS256, HS384, HS512. |
| `EmptyElementForKeyConfiguration` `FailedToResolveVariable` `InvalidConfigurationForActionAndAlgorithmFamily` `InvalidConfigurationForVerify` `InvalidEmptyElement` `InvalidFamiliesForAlgorithm` `InvalidKeyConfiguration` `InvalidNameForAdditionalClaim` `InvalidNameForAdditionalHeader` `InvalidPublicKeyId` `InvalidPublicKeyValue` `InvalidSecretInConfig` `InvalidTypeForAdditionalClaim` `InvalidTypeForAdditionalHeader` `InvalidValueForElement` `InvalidValueOfArrayAttribute` `InvalidVariableNameForSecret` `MissingConfigurationElement` `MissingElementForKeyConfiguration` `MissingNameForAdditionalClaim` `MissingNameForAdditionalHeader` | 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](https://docs.apigee.com/api-platform/fundamentals/what-you-need-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](https://docs.apigee.com/api-platform/reference/policies/verify-jws-policy#runtime-errors) table above. The fault name is the last part of the fault code. | `fault.name Matches "TokenExpired"` |
| `JWS.failed` | All JWS policies set the same variable in the case of a failure. | `jws.JWS-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
```
JavaScript-1(fault.name Matches "TokenExpired")JWS.failed=true
```