Help Center/ API Request Signing Guide/ Developer Guide/ API Signature Authentication Principles/ Example of the API Signature Authentication Mechanism
Updated on 2026-03-05 GMT+08:00
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Example of the API Signature Authentication Mechanism

The following procedure uses the Virtual Private Cloud (VPC) query API as an example. Assume that the original request is as follows:

GET https://service.region.example.com/v1/77b6a44cba5143ab91d13ab9a8ff44fd/vpcs?limit=2&marker=13551d6b-755d-4757-b956-536f674975c0 HTTP/1.1
Host: service.region.example.com
X-Sdk-Date: 20191115T033655Z
  1. Construct a standard request. 

    GET
/v1/77b6a44cba5143ab91d13ab9a8ff44fd/vpcs/
limit=2&marker=13551d6b-755d-4757-b956-536f674975c0
content-type:application/json
host:service.region.example.com
x-sdk-date:20191115T033655Z

content-type;host;x-sdk-date
e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
    • HTTPRequestMethod 
      GET
    • CanonicalURI
      The URI of the VPC query API is /v1/{project_id}/vpcs, where project_id is 77b6a44cba5143ab91d13ab9a8ff44fd. The standard URI is as follows: 
      /v1/77b6a44cba5143ab91d13ab9a8ff44fd/vpcs/
    • CanonicalQueryString
      The VPC query API has two optional parameters: limit (number of records returned on each page) and marker (start VPC ID for pagination query). The standard query string is as follows: 
      limit=2&marker=13551d6b-755d-4757-b956-536f674975c0
    • CanonicalHeaders
      Requests for calling the VPC query API contain the X-Sdk-Date, Host (cloud service endpoint), and Content-Type headers. A standard header is as follows: 
      content-type:application/json
host:service.region.example.com
x-sdk-date:20191115T033655Z
                               //This is a blank line.
    • SignedHeaders
      Add the following three headers: Content-Type, Host, and X-Sdk-Date. 
      content-type;host;x-sdk-date
    • RequestPayload
      This example uses GET as an example, and the request body is empty. After hash processing, the request body (empty string) is as follows: 
      e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855

  2. Create a to-be-signed string. 

    SDK-HMAC-SHA256
20191115T033655Z
b25362e603ee30f4f25e7858e8a7160fd36e803bb2dfe206278659d71a9bcd7a
    • Algorithm 
      SDK-HMAC-SHA256
    • RequestDateTime 
      20191115T033655Z
    • HashedCanonicalRequest

      Generate a hash value using the SHA-256 algorithm based on the standard request constructed in 1.

      b25362e603ee30f4f25e7858e8a7160fd36e803bb2dfe206278659d71a9bcd7a

  3. Calculate a signature. 

    Signature=f12f84a5ecf9eff3206499c4a55b13d1adad745dc8624a2e31f15c6b381d5b80

    Assume that the SK is MFyf***VmHc. The signature value is obtained by performing the hash operation on the SK and the signature character string in 2.

    signature = HexEncode(HMAC(MFyf***VmHc, b25362e603ee30f4f25e7858e8a7160fd36e803bb2dfe206278659d71a9bcd7a))

  4. Add the signature to the request header.

    Add the signature information to the Authorization message header. The SignedHeaders field includes the three headers from 1: Content-Type, Host, and X-Sdk-Date. Assume that the access key (AK) is QTWA***KYUC.

    Authorization: SDK-HMAC-SHA256 Access=QTWA***KYUC, SignedHeaders=content-type;host;x-sdk-date, Signature=f12f84a5ecf9eff3206499c4a55b13d1adad745dc8624a2e31f15c6b381d5b80

  5. Complete signature request. 

    GET /v1/77b6a44cba5143ab91d13ab9a8ff44fd/vpcs?limit=2&; marker=13551d6b-755d-4757-b956-536f674975c0 HTTP/1.1
Host: service.region.example.com
Content-Type: application/json
x-sdk-date: 20191115T033655Z
Authorization: SDK-HMAC-SHA256 Access=QTWA***KYUC, SignedHeaders=content-type;host;x-sdk-date, Signature=f12f84a5ecf9eff3206499c4a55b13d1adad745dc8624a2e31f15c6b381d5b80

Example request for calling an API with a curl command:

curl -X GET "https://service.region.example.com/v1/77b6a44cba5143ab91d13ab9a8ff44fd/vpcs?limit=2&marker=13551d6b-755d-4757-b956-536f674975c0" -H "content-type: application/json" -H "X-Sdk-Date: 20191115T033655Z" -H "host: service.region.example.com" -H "Authorization: SDK-HMAC-SHA256 Access=QTWA***KYUC, SignedHeaders=content-type;host;x-sdk-date, Signature=f12f84a5ecf9eff3206499c4a55b13d1adad745dc8624a2e31f15c6b381d5b80" -d $''