CkPython

Verify the RSA Signature of a SHA256 Hash

See more RSA Examples

Demonstrates how to verify an RSA signature of a SHA256 hash. CkPython

import sys
import chilkat

success = False

# This example assumes the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# Let's say you have a file containing the 32-bytes of a SHA256 hash,
# and a file that is an RSA signature of those 32 bytes.
# Here's how you verify using the RSA public key found in a PEM.

pubKey = chilkat.CkPublicKey()
success = pubKey.LoadFromFile("rsaPubKey.pem")
if (success == False):
    print(pubKey.lastErrorText())
    sys.exit()

rsa = chilkat.CkRsa()

# Get the public key.
success = rsa.UsePublicKey(pubKey)
if (success == False):
    print(rsa.lastErrorText())
    sys.exit()

# Get the 32-byte SHA256 hash.
bdHash = chilkat.CkBinData()
success = bdHash.LoadFile("myHash.sha256")
if (success == False):
    print("Failed to load SHA256 hash.")
    sys.exit()

# Get the RSA signature to be validated.
bdSig = chilkat.CkBinData()
success = bdSig.LoadFile("mySig.sig")
if (success == False):
    print("Failed to load RSA signature.")
    sys.exit()

# Verify the signature against the SHA256 hash.
enc = "base64"
rsa.put_EncodingMode(enc)
success = rsa.VerifyHashENC(bdHash.getEncoded(enc),"sha256",bdSig.getEncoded(enc))
if (success == False):
    print(rsa.lastErrorText())
    sys.exit()

print("Signature validated.")