CkPython

RSA Signature/Verify with .key and .cer

See more RSA Examples

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature. 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.

privKey = chilkat.CkPrivateKey()

# Load the private key from an RSA .key file:
success = privKey.LoadPemFile("privateKey.key")
if (success == False):
    print(privKey.lastErrorText())
    sys.exit()

rsa = chilkat.CkRsa()

# Import the private key into the RSA component:
success = rsa.UsePrivateKey(privKey)
if (success == False):
    print(rsa.lastErrorText())
    sys.exit()

# Create the signature as a hex string:
rsa.put_EncodingMode("hex")

strData = "This is the string to be signed."

# Sign the string using the sha256 hash algorithm.
# Other valid choices are "md2", "sha1", "sha384",
# "sha512", and "md5".
hexSig = rsa.signStringENC(strData,"sha256")

print(hexSig)

# Load a digital certificate from a .cer file:
cert = chilkat.CkCert()

success = cert.LoadFromFile("myCert.cer")
if (success == False):
    print(cert.lastErrorText())
    sys.exit()

pubKey = chilkat.CkPublicKey()
cert.GetPublicKey(pubKey)

# Now verify using a new instance of the RSA object:
rsa2 = chilkat.CkRsa()

# Import the public key into the RSA object:
success = rsa2.UsePublicKey(pubKey)
if (success == False):
    print(rsa2.lastErrorText())
    sys.exit()

# The signature is a hex string, so make sure the EncodingMode is correct:
rsa2.put_EncodingMode("hex")

# Verify the signature:
success = rsa2.VerifyStringENC(strData,"sha256",hexSig)
if (success == False):
    print(rsa2.lastErrorText())
    sys.exit()

print("Success.")