:Call an API operation

http://endpoint/?Action=xx&parameters

1. Construct a normalized request string (Canonicalized Query String) using request parameters.
   1. Request parameters are ordered alphabetically by their names (including public request parameters and user-defined parameters for the given request interfaces described in this document, but excluding the Signature parameter mentioned in public request parameters).
      Notice For a request submitted using the GET method, these parameters constitute the parameter section of the request URL (that is, the section in the URL following “?” and connected by “&”).
   2. The name and value of each request parameter are encoded. The names and values must be URL-encoded using the UTF-8 character set. The URL encoding rules are as follows:
      1. The characters A-Z, a-z, 0-9, and “-“, “_”, “.”, “~” are not encoded.
      2. Other characters are encoded in “%XY” format, with XY representing the characters’ ASCII code in hexadecimal notation. For example, the English double quotes (“) are encoded as %22.
      3. Extended UTF-8 characters are encoded in “%XY%ZA…” format.
      4. It must be noted that an English space is encoded as %20, rather than the plus sign (+).
         Notice Generally, libraries that support URL encoding (such as Java’s java.net.URLEncoder) encode characters according to the rules for the MIME-type “application/x-www-form-urlencoded”. If this encoding method is used, replace the plus signs (+) in the encoded strings with %20, the asterisks (*) with %2A, and change %7E back to the tilde (~) to conform to the preceding encoding rules.
   3. Connect the encoded parameter names and values with the equal sign (=).
   4. Sort the parameter name and value pairs connected by equal signs in alphabetical order, and connect them with the (&) symbol to produce the Canonicalized Query String.
2. Follow the following rules to construct the string used for signature calculation by using the Canonicalized Query String constructed in the previous step:

   StringToSign=
   HTTPMethod + "&" +
   percentEncode("/") + "&" +
   percentEncode(CanonicalizedQueryString)

   Parameter description:
   • HTTPMethod: the HTTP method used for request submission, for example, GET.
   • percentEncode(“/“): the coded value for the character “/“ according to the URL encoding rules described in 1.b, namely, “%2F”.
   • percentEncode(CanonicalizedQueryString): the encoded string of the Canonicalized Query String constructed in Step 1, produced by following the URL encoding rules described in 1.b.
3. Use the preceding signature sting to calculate the signature’s HMAC value based on RFC2104 definitions.
   Notice The Key used for calculating the signature is the Access Key Secret held by you, which ends with the “&” character (ASCII:38) and is based on the SHA1 hashing.
4. According to Base64 encoding rules, encode the preceding HMAC value into a string, which gives you the signature value.
5. Add the signature to the request as the Signature parameter. The result is the signed API request.
   Note When the signature is submitted to SAG as the final request parameter value, the signature must be URL-encoded based on the rules defined in RFC 3986. The following example shows the request URL of the DescribeSmartAccessGateways operation before the request is signed:

   http://smartag.cn-shanghai.aliyuncs.com/?Timestamp=2016-04-23T12:46:24Z&Format=XML&AccessKeyId=testid&Action=DescribeSmartAccessGateways&SignatureMethod=HMAC-SHA1&RegionId=region1&SignatureNonce=3ee8c1b8-83d3-44af-a94f-4e0ad82fd6cf&Version=2018-03-13&SignatureVersion=1.0

6. The following string is the string-to-sign:

   GET&%2F&AccessKeyId%3Dtestid&Action%DescribeSmartAccessGateways&Format%3DXML&SignatureMethod%3DHMAC-SHA1&SignatureNonce%3D3ee8c1b8-83d3-44af-a94f-4e0ad82fd6cf&SignatureVersion%3D1.0&Timestamp%3D2018-04-23T12%253A46%253A24Z&Version%3D2018-03-13

7. In this example, the AccessKey ID is testid and the AccessKey secret is testsecret. The secret key that is used to calculate the HMAC value of the string-to-sign is testsecret&. The signature is CT9X0VtwR86fNWSnsc6v8YGOjuE=.
   The following URL is the signed request URL after the signature is added to the request as the Signature parameter:

   http://smartag.cn-shanghai.aliyuncs.com/?Timestamp=2016-04-23T12%3A46%3A24Z&Format=XML&AccessKeyId=testid&Action=DescribeSmartAccessGateways&SignatureMethod=HMAC-SHA1&RegionId=region1&SignatureNonce=3ee8c1b8-83d3-44af-a94f-4e0ad82fd6cf&SignatureVersion=1.0&Version=2018-03-13&Signature=CT9X0VtwR86fNWSnsc6v8YGOjuE%3D