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.

Download Chilkat RSA Public-Key Encryption ActiveX

LOCAL loRsa
LOCAL lnSuccess
LOCAL lcStrData
LOCAL lcHexSig

loRsa = CreateObject('Chilkat.Rsa')

*  Any string argument automatically begins the 30-day trial.

lnSuccess = loRsa.UnlockComponent("30-day trial")
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX("RSA component unlock failed")
    QUIT
ENDIF

*  Generate a 1024-bit RSA key pair.
loRsa.GenerateKey(1024)

*  This example will sign a string, and receive the signature
*  in a hex-encoded string.  Therefore, set the encoding mode
*  to "hex":
loRsa.EncodingMode = "hex"

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

*  Sign the string using the  md5 hash algorithm.
*  Other valid choices are "md2" and "sha-1".

lcHexSig = loRsa.SignStringENC(lcStrData,"md5")

? lcHexSig
? loRsa.LastErrorText

*  Now verify the signature:
lnSuccess = loRsa.VerifyStringENC(lcStrData,"md5",lcHexSig)
IF (lnSuccess = 1) THEN
    =MESSAGEBOX("Signature verified!")
ELSE
    ? loRsa.LastErrorText
ENDIF

*  Try it with an invalid signature:
lnSuccess = loRsa.VerifyStringENC(lcStrData,"md5","not a valid sig")
IF (lnSuccess = 1) THEN
    =MESSAGEBOX("Signature verified!")
ELSE
    ? loRsa.LastErrorText
ENDIF

*  Try it with invalid data:
lnSuccess = loRsa.VerifyStringENC("Not the original data","md5",lcHexSig)
IF (lnSuccess = 1) THEN
    =MESSAGEBOX("Signature verified!")
ELSE
    ? loRsa.LastErrorText
ENDIF

*  Try it with the wrong hash algorithm:
lnSuccess = loRsa.VerifyStringENC(lcStrData,"sha-1",lcHexSig)
IF (lnSuccess = 1) THEN
    =MESSAGEBOX("Signature verified!")
ELSE
    ? loRsa.LastErrorText
ENDIF