Generate RSA Key and Sign a String

Demonstrates how to generate a new RSA public/private key pair and use it to generate a signature for a string. The (binary) digital signature is returned as a hexidecimalized string.

 Chilkat Python Module Downloads for Windows, Linux, and MAC OS X

import sys
import chilkat

rsa = chilkat.CkRsa()

#  Any string argument automatically begins the 30-day trial.
success = rsa.UnlockComponent("30-day trial")
if (success != True):
    print "RSA component unlock failed"
    sys.exit()

#  Generate a 1024-bit RSA key pair.
rsa.GenerateKey(1024)

#  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")

#  If some other non-Chilkat application or web service is going to be verifying
#  the signature, it is important to match the byte-ordering.
#  The LittleEndian property may be set to True
#  for little-endian byte ordering,
#  or False  for big-endian byte ordering.
#  Microsoft apps typically use little-endian, while
#  OpenSSL and other services (such as Amazon CloudFront)
#  use big-endian.
rsa.put_LittleEndian(False)

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

#  Sign the string using the  md5 hash algorithm.
#  Other valid choices are "md2", "sha256", "sha384",
#  "sha512", and "sha-1".
hexSig = rsa.signStringENC(strData,"md5")

print hexSig
print rsa.lastErrorText()

#  Now verify the signature:
success = rsa.VerifyStringENC(strData,"md5",hexSig)
if (success == True):
    print "Signature verified!"
else:
    print rsa.lastErrorText()

#  Try it with an invalid signature:
success = rsa.VerifyStringENC(strData,"md5","not a valid sig")
if (success == True):
    print "Signature verified!"
else:
    print rsa.lastErrorText()

#  Try it with invalid data:
success = rsa.VerifyStringENC("Not the original data","md5",hexSig)
if (success == True):
    print "Signature verified!"
else:
    print rsa.lastErrorText()

#  Try it with the wrong hash algorithm:
success = rsa.VerifyStringENC(strData,"sha-1",hexSig)
if (success == True):
    print "Signature verified!"
else:
    print rsa.lastErrorText()