RSA Signature/Verify with .key and .cer

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

Download Chilkat RSA ActiveX

LOCAL loPrivKey
LOCAL lnSuccess
LOCAL lcPrivKeyXml
LOCAL loRsa
LOCAL lcStrData
LOCAL lcHexSig
LOCAL loCert
LOCAL loPubKey
LOCAL loRsa2

loPrivKey = CreateObject('Chilkat.PrivateKey')

*  Load the private key from an RSA .key file:
lnSuccess = loPrivKey.LoadPemFile("privateKey.key")
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loPrivKey.LastErrorText)
    QUIT
ENDIF

*  Get the private key in XML format:
lcPrivKeyXml = loPrivKey.GetXml()

loRsa = CreateObject('Chilkat.Rsa')

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

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

*  Import the private key into the RSA component:
lnSuccess = loRsa.ImportPrivateKey(lcPrivKeyXml)
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loRsa.LastErrorText)
    QUIT
ENDIF

*  Create the signature as a hex string:
loRsa.EncodingMode = "hex"

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

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

lcHexSig = loRsa.SignStringENC(lcStrData,"sha-1")

? lcHexSig

*  Load a digital certificate from a .cer file:
loCert = CreateObject('Chilkat.Cert')

lnSuccess = loCert.LoadFromFile("myCert.cer")
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loCert.LastErrorText)
    QUIT
ENDIF

loPubKey = loCert.ExportPublicKey()

*  Now verify using a separate instance of the RSA object:
loRsa2 = CreateObject('Chilkat.Rsa')

*  Import the public key into the RSA object:
lnSuccess = loRsa2.ImportPublicKey(loPubKey.GetXml())
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loRsa2.LastErrorText)
    QUIT
ENDIF

RELEASE loPubKey

*  The signature is a hex string, so make sure the EncodingMode is correct:
loRsa2.EncodingMode = "hex"

*  Verify the signature:
lnSuccess = loRsa2.VerifyStringENC(lcStrData,"sha-1",lcHexSig)
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loRsa2.LastErrorText)
    QUIT
ENDIF

=MESSAGEBOX("Success.")