(Visual FoxPro) 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.

Note: This example requires Chilkat v11.0.0 or greater.

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ActiveX for 32-bit and 64-bit Windows

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

lnSuccess = 0

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

loPrivKey = CreateObject('Chilkat.PrivateKey')

* Load the private key from an RSA .key file:
lnSuccess = loPrivKey.LoadPemFile("privateKey.key")
IF (lnSuccess = 0) THEN
    ? loPrivKey.LastErrorText
    RELEASE loPrivKey
    CANCEL
ENDIF

loRsa = CreateObject('Chilkat.Rsa')

* Import the private key into the RSA component:
lnSuccess = loRsa.UsePrivateKey(loPrivKey)
IF (lnSuccess = 0) THEN
    ? loRsa.LastErrorText
    RELEASE loPrivKey
    RELEASE loRsa
    CANCEL
ENDIF

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

lcStrData = "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".
lcHexSig = loRsa.SignStringENC(lcStrData,"sha256")

? lcHexSig

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

lnSuccess = loCert.LoadFromFile("myCert.cer")
IF (lnSuccess = 0) THEN
    ? loCert.LastErrorText
    RELEASE loPrivKey
    RELEASE loRsa
    RELEASE loCert
    CANCEL
ENDIF

loPubKey = CreateObject('Chilkat.PublicKey')
loCert.GetPublicKey(loPubKey)

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

* Import the public key into the RSA object:
lnSuccess = loRsa2.UsePublicKey(loPubKey)
IF (lnSuccess = 0) THEN
    ? loRsa2.LastErrorText
    RELEASE loPrivKey
    RELEASE loRsa
    RELEASE loCert
    RELEASE loPubKey
    RELEASE loRsa2
    CANCEL
ENDIF

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

* Verify the signature:
lnSuccess = loRsa2.VerifyStringENC(lcStrData,"sha256",lcHexSig)
IF (lnSuccess = 0) THEN
    ? loRsa2.LastErrorText
    RELEASE loPrivKey
    RELEASE loRsa
    RELEASE loCert
    RELEASE loPubKey
    RELEASE loRsa2
    CANCEL
ENDIF

? "Success."

RELEASE loPrivKey
RELEASE loRsa
RELEASE loCert
RELEASE loPubKey
RELEASE loRsa2