Method: projects.serviceAccounts.signJwt

Signs a JWT using a service account's system-managed private key.

HTTP request

POST https://iamcredentials.googleapis.com/v1/{name=projects/*/serviceAccounts/*}:signJwt

The URL uses gRPC Transcoding syntax.

Path parameters

Parameters
name

string

Required. The resource name of the service account for which the credentials are requested, in the following format: projects/-/serviceAccounts/{ACCOUNT_EMAIL_OR_UNIQUEID}. The - wildcard character is required; replacing it with a project ID is invalid.

Authorization requires the following IAM permission on the specified resource name:

  • iam.serviceAccounts.signJwt

Request body

The request body contains data with the following structure:

JSON representation
{
  "delegates": [
    string
  ],
  "payload": string
}
Fields
delegates[]

string

The sequence of service accounts in a delegation chain. Each service account must be granted the roles/iam.serviceAccountTokenCreator role on its next service account in the chain. The last service account in the chain must be granted the roles/iam.serviceAccountTokenCreator role on the service account that is specified in the name field of the request.

The delegates must have the following format: projects/-/serviceAccounts/{ACCOUNT_EMAIL_OR_UNIQUEID}. The - wildcard character is required; replacing it with a project ID is invalid.

payload

string

Required. The JWT payload to sign. Must be a serialized JSON object that contains a JWT Claim Set. For example: {"sub": "user@example.com", "iat": 313435}

If the claim set contains an exp claim, it must be an integer timestamp that is not in the past and at most 12 hours in the future.

Response body

If successful, the response body contains data with the following structure:

JSON representation
{
  "keyId": string,
  "signedJwt": string
}
Fields
keyId

string

The ID of the key used to sign the JWT. The key used for signing will remain valid for at least 12 hours after the JWT is signed. To verify the signature, you can retrieve the public key in several formats from the following endpoints:

  • RSA public key wrapped in an X.509 v3 certificate: https://www.googleapis.com/service_accounts/v1/metadata/x509/{ACCOUNT_EMAIL}
  • Raw key in JSON format: https://www.googleapis.com/service_accounts/v1/metadata/raw/{ACCOUNT_EMAIL}
  • JSON Web Key (JWK): https://www.googleapis.com/service_accounts/v1/metadata/jwk/{ACCOUNT_EMAIL}
signedJwt

string

The signed JWT. Contains the automatically generated header; the client-supplied payload; and the signature, which is generated using the key referenced by the kid field in the header.

After the key pair referenced by the keyId response field expires, Google no longer exposes the public key that can be used to verify the JWT. As a result, the receiver can no longer verify the signature.

Authorization Scopes

Requires one of the following OAuth scopes:

  • https://www.googleapis.com/auth/iam
  • https://www.googleapis.com/auth/cloud-platform

For more information, see the Authentication Overview.

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