Python

################################################################
#Script Name	: Advanced Authentication Python example       #
#Description	: This script contains functions that generate #
#                 the fingerprint and fingerprint signature by #
#                 reading the private key from an external     #
#                 file, this is just an example STORE YOUR     #
#                 CREDENTIALS SAFELY                           #
################################################################

import base64
import logging

from cryptography.exceptions import AlreadyFinalized
from cryptography.exceptions import UnsupportedAlgorithm
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import padding
from cryptography.hazmat.primitives.asymmetric import rsa


# set up logger
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# function to be used to generate the hashed fingerprint, input argument is the fingerprint order concatenated string
def fingerprintHash(fingerprint):
    try:
        # get digest instance
        digest = hashes.Hash(
            algorithm=hashes.SHA512(),
            backend=default_backend()
        )

        # create hash
        digest.update(fingerprint.encode('utf-8'))
        hash_bytes = digest.finalize()

        # convert/encode in hex
        return hash_bytes.hex()

    except (UnsupportedAlgorithm, AlreadyFinalized):
        logger.exception("Hashing failed")

# function to be used to generate the fingerprint signature, input arguments are the hashed fingerprint to be signed and the private 2048 RSA key file path
def fingerprintSignature(fingerprintH, keyPath):
    try:
        # load private key
        with open(keyPath, "rb") as key_file:
            privateKey = serialization.load_pem_private_key(
                key_file.read(),
                password=None,
                backend=default_backend()
            )

        # sign string
        signature = privateKey.sign(
            data=fingerprintH.encode('utf-8'),
            padding=padding.PKCS1v15(),
            algorithm=hashes.SHA512()
        )

        return base64.b64encode(signature)
    except UnsupportedAlgorithm:
        logger.exception("Signing failed")

if __name__ == '__main__':

    keyPath = "C:\\Users\\user\\Desktop\\privateKey.pem"

    # fingerprint example for Internal transfer, fingerpint order: amount, currencyCode, fromWalletId, toWalletId, token (http://apidoc-demo.soldo.com/v2/zgxiaxtcyapyoijojoef.html#internal-transfer)
    fingerprint = "300EUR764674e4-8a94-47cc-b5ad-2430aba5aaa697191a41-9603-46f1-b751-e44ebda1bb9d4UH8WMO8BVLFNHUXFB9E"
    logger.info("Fingerprint: %s", fingerprint)

    # fingerprint hash for X-Soldo-Fingerprint header
    fingerprintH = fingerprintHash(fingerprint)
    logger.info("Hash: %s", fingerprintH)

    # fingerprint hash signature for X-Soldo-Fingerprint-Signature header
    fingerprintS = fingerprintSignature(fingerprintH, keyPath)
    logger.info("Signature: %s", fingerprintS)