Updated on 2026-09-21 GMT+08:00

Signature Data

Function

This API is used to digitally sign a message or digest using the private key of an asymmetric key.

Constraints

Only the asymmetric key whose key_usage is SIGN_VERIFY can be used for signature.

SM2 keys can only be used to sign message digests.

Calling Method

For details, see Calling APIs.

URI

POST /v1.0/{project_id}/kms/sign

**Table 1** Path Parameters
Parameter	Mandatory	Type	Description
project_id	Yes	String	Definition Project ID. For details, see Obtaining a Project ID. Constraints N/A Range The value returned by the IAM API is used, which contains 32 characters. Default Value N/A

Request Parameters

**Table 2** Request header parameters
Parameter	Mandatory	Type	Description
X-Auth-Token	Yes	String	Definition User token. It can be obtained by calling the IAM API. The value of X-Subject-Token in the response header is the user token. Constraints N/A Range Obtain the value by calling the IAM API for obtaining the user token. Default Value N/A

**Table 3** Request body parameters
Parameter	Mandatory	Type	Description
key_id	Yes	String	Definition Key ID Constraints The value must be a 36-byte ID. The value must match the regular expression ^[0-9a-z]{8}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{12}$. Range N/A Default Value N/A
message	Yes	String	Definition Message digest or message to be signed Constraints The value must be less than 4,096 bytes and encoded using Base64. Range N/A Default Value N/A
signing_algorithm	Yes	String	Definition Signature algorithm Constraints N/A Range RSASSA_PSS_SHA_256 RSASSA_PSS_SHA_384 RSASSA_PSS_SHA_512 RSASSA_PKCS1_V1_5_SHA_256 RSASSA_PKCS1_V1_5_SHA_384 RSASSA_PKCS1_V1_5_SHA_512 ECDSA_SHA_256 ECDSA_SHA_384 ECDSA_SHA_512 SM2DSA_SM3 ED25519_SHA_512 ED25519_PH_SHA_512 Default Value N/A
message_type	No	String	Definition Message type Constraints N/A Range DIGEST: Message digest RAW: Original message Default Value DIGEST
sequence	No	String	Definition A 36-byte serial number of a request message, for example, 919c82d4-8046-4722-9094-35c3c6524cff. Constraints N/A Range N/A Default Value N/A

Response Parameters

Status code: 200

**Table 4** Response body parameters
Parameter	Type	Description
key_id	String	Definition Key ID Range N/A
signature	String	Definition Base64-encoded signature value Range N/A

Example Requests

Sign messages and digests using the key whose ID is 0d0466b0-e727-4d9c-b35d-f84bb474a37f and the RSASSA_PKCS1_V1_5_SHA_256 algorithm.

{
  "key_id" : "0d0466b0-e727-4d9c-b35d-f84bb474a37f",
  "signing_algorithm" : "RSASSA_PKCS1_V1_5_SHA_256",
  "message" : "MmFiZWE0ZjI3ZGIxYTkzY2RmYmEzM2YwMTA1YmJjYw=="
}

Example Responses

Status code: 200

Request succeeded.

{
  "key_id" : "0d0466b0-e727-4d9c-b35d-f84bb474a37f",
  "signature" : "jFUqQESGBc0j6k9BozzrP9YL4qk8/W9DZRvK6XXX..."
}

Status Codes

Status Code	Description
200	Request succeeded.

Error Codes

See Error Codes.

Parent Topic: Signature and Verification