Signature

Signature - a string in hexadecimal format formed by one-way coding. You cannot decode or generate this string without knowing all the necessary components. The signature is based on the potential importance of each query parameter.

SHA-1 hash algorithm is used for signature generating.

Secure Hash Algorithm 1 – cryptographic hashing algorithm. For an input message of arbitrary length (a maximum of 2^64 bits, approximately equal to 2 exabytes), the algorithm generates a 160-bit hash value, also called a message digest. It is used in many cryptographic applications and protocols.

Python code snippet

import hashlib

request_params = {
    "site_id": 24,
    "site_login": "443122443122",
    "customer_ip": "185.56.232.170",
    "currency": "usd",
    "signature": "1234566443"
}

params = {}
for key, value in request_params.items(): #
    if isinstance(v, list):
        new_v = ';'.join(sorted(map(str, v)))
        params[str(k)] = str(new_v)
    else:
        params[str(k)] = str(v)
        
sign_str = ';'.join(
    ['%s:%s' % (k.lower(), params[k]) for k in
sorted(params.keys()) if params[k].strip() != '']) + ';'
signature = hashlib.sha1(sign_str.encode('utf-8') +
salt.encode('utf-8')).hexdigest()

Signature generating algorithm

1. A signature string is generated:

   • all query parameters are sorted alphabetically;

   • sorted not empty parameters are connected in series to one line (concatenation) using the symbol-separator between them;

   • the end of the line is appended with the site salt using the symbol-separator

2. SHA-1 hash is taken from the received string.

Signature generating rules

• Signed string coding – UTF-8;

• Query parameter names are presented in lower case. The string can be composed of Latin letters from a to z, numbers from 0 to 9, underlining sign "_";

• A semicolon is used as the delimiter between parameters ”;”;

• Each parameter is attached as a substring ”param_name:param_value”, where param name – a parameter name, param_value – parameter value, a colon - internal delimiter;

• Parameters which value is an empty string ”” – are skipped;

• If the parameter value is an array, then its elements are also sorted according to the growth of their keys and connected in series by a delimiter. In this case, the array elements (nested arrays) are skipped, and the delimiter character is not added;

• To avoid double signing, the "signature" parameter is always excluded from the signature.

In summary, the process of generating a signature using the SHA-1 hash algorithm and the described rules helps ensure data integrity and authenticity by providing a unique identifier that can be used to verify the validity of the data while maintaining a secure and consistent approach to signing.