(CkPython) RSA Sign with PKCS8 Encrypted Key

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it).

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import sys
import chilkat

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

pkey = chilkat.CkPrivateKey()

# Load the private key from an RSA PEM file:
success = pkey.LoadPkcs8EncryptedFile("raul_privateKey.key","a0123456789")

# Get the private key in XML format:
pkeyXml = pkey.getXml()

rsa = chilkat.CkRsa()

# Import the private key into the RSA component:
success = rsa.ImportPrivateKey(pkeyXml)
if (success != True):
    print(rsa.lastErrorText())
    sys.exit()

# This example will sign a string, and receive the signature
# in a hex-encoded string.  Therefore, set the encoding mode
# to "hex":
rsa.put_EncodingMode("hex")

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

# Sign the string using the sha-1 hash algorithm.
# Other valid choices are "md2" and "md5".
hexSig = rsa.signStringENC(strData,"sha-1")

print(hexSig)

# Now verify with the public key.
# This example shows how to use the public key from 
# a digital certificate (.cer file)
cert = chilkat.CkCert()
success = cert.LoadFromFile("raul_publicKey.cer")
if (success != True):
    print(cert.lastErrorText())
    sys.exit()

# pubKey is a CkPublicKey
pubKey = cert.ExportPublicKey()

# Get the private key in XML format:
pubKeyXml = pubKey.getXml()

rsa2 = chilkat.CkRsa()
success = rsa2.ImportPublicKey(pubKeyXml)
if (success != True):
    print(rsa2.lastErrorText())
    sys.exit()

# Verify the signature against the original data:
rsa2.put_EncodingMode("hex")
success = rsa2.VerifyStringENC(strData,"sha-1",hexSig)
if (success != True):
    print(rsa2.lastErrorText())
    sys.exit()

print("Signature verified!")

# Verify with incorrect data:
success = rsa2.VerifyStringENC("something else","sha-1",hexSig)
if (success != True):
    print("Signature not verified! (which was expected in this case)")
else:
    print("Hmmm... that's not right...")