(CkPython) Verfies an RSA Signature

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Verifies an RSA signature against the original data.

Chilkat Python Downloads install with pip pip3 install chilkat or download... Python Module for Windows, MacOS, Linux, Alpine Linux, Solaris

import sys
import chilkat

# The following data was signed by the following example:
# RSA Sign using a Private Key on a USB Token or Smartcard
bd = chilkat.CkBinData()

for i in range(0,101):
    bd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex")

# Load the signature
bdSig = chilkat.CkBinData()
success = bdSig.LoadFile("rsaSignatures/test1.sig")
if (success == False):
    print("Failed to load the RSA signature")
    sys.exit()

# Get the public key to be used for signature verification.
pubKey = chilkat.CkPublicKey()
success = pubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
if (success == False):
    print(pubKey.lastErrorText())
    sys.exit()

rsa = chilkat.CkRsa()
rsa.ImportPublicKeyObj(pubKey)

# Verify the hash of the data against the signature.
# We pass in the original data.  Internally, the hash is generated
# and used to validate the signature.
# Validating the RSA signature means two things:  
# (1) the original data is exactly what was signed, and 
# (2) it was signed by the owner of the RSA private key.
success = rsa.VerifyBd(bd,"sha256",bdSig)

if (success == False):
    print(rsa.lastErrorText())
    print("Signature invalid.")
else:
    print("Signature valid.")