Marketplace:Compute Signature

IoT platform authenticates the sender of each API access request, so API requests must include Signature information in the request.

1. Get the key ID and key

Before actually calculating the signature, there are several necessary parameters that need to be prepared. When signing, you need to sign in the console. AccessKey managementpage to view your key ID and key . Among them, key ID used to identify visitors; key is the key used to encrypt the signature string and verify the signature string on the server side, must be strictly confidential .

2. Signature method

Sign the request as follows:

2.1. Construct a Canonicalized Query String using the request parameters.

a. Sort parameters. In the dictionary order of the parameter names, the request parameters (including Common parametersand interface, but cannot include Signature parameter itself) to sort.

B. Perform URL encoding on the name and value of each request parameter. Names and values are to be used in accordance with the UTF-8 character set. RFC3986rules for encoding. The encoding rules are as follows: ■Characters A ~ Z, a ~ z, 0~9, and characters - , _ , . , ~ no coding. ■Other characters are encoded %XY format, where XY is the hexadecimal representation of the character corresponding to the ASCII code. For example, double quotation marks in English " the corresponding coding is % 22 . ■Extended UTF-8 characters, encoded %XY%ZA&help; the format of. ■English spaces should be encoded % 20 instead of a plus + . The encoding method and application/x-www-form-urlencoded the MIME format encoding algorithm is similar but different. If you are using the Java Standard Library. java.net.URLEncoder , you can use the standard library first percentEncode encoding, followed by a plus sign in the encoded character + replace % 20 , Asterisk * replace % 2A , % 7E replace with tilde ~ , you can get the encoded string described by the above rule.

private static final String ENCODING = "UTF-8";
private static String percentEncode(String value) throws UnsupportedEncodingException {
    return value != null ? URLEncoder.encode(value, ENCODING).replace("+", "%20").replace("*", "%2A").replace("%7E", "~") : null;
}

c. Connect the encoded parameter names and values with an equal sign (=). d. Use the strings obtained by connecting English equal signs in the dictionary order of parameter names & symbolic connection. Once completed, the canonicalized request string (CanonicalizedQueryString) is obtained.

2.2. Construct a signature string.

Use percentEncode process the normalized string obtained in step 1 to construct the string used to calculate the signature. The following rules can be referred:

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

Parameter description: ○HTTPMethod: The HTTP method that sends the request, such as GET. ○percentEncode("/"): the value obtained by UTF-8 encoding the character "/", that is, "% 2F". ○percentEncode(CanonicalizedQueryString): Your canonicalized request string.

2.3. Calculate the HMAC value.

According RFC2104the definition of, using the string obtained in step 2. StringToSign calculates the signature HMAC value.

HMAC-SHA1( AccessSecret, UTF-8-Encoding-Of(StringToSign) )

2.4. Calculate the signature value.

Encode the HMAC value in step 3 into a string according to the Base64 encoding rule to obtain the Signature value.

Signature = Base64( HMAC-SHA1( AccessSecret, UTF-8-Encoding-Of(StringToSign) ) )

1

Signature=Base64(HMAC-SHA1(AccessSecret,UTF-8-Encoding-Of(StringToSign)))

2.5. Add a signature.

The resulting signature value is used as Signature parameters, according RFC3986after encoding the URL of the rule, add it to the request parameters to complete the process of signing the request.