Visual FoxPro

Verify an RSA Signature Against the Signed String

See more Apple Keychain Examples

Demonstrates how to validate an RSA Signature against the string that was signed. Visual FoxPro

LOCAL lnSuccess
LOCAL loSb
LOCAL lnCrlfLineEnding
LOCAL i
LOCAL lcBase64_rsa_sig
LOCAL loPubKey
LOCAL loRsa
LOCAL lcSignedString

lnSuccess = 0

* Create the same string we previously signed in this example: 
* RSA Sign utf-8 Bytes of String to get Base64 RSA Signature

loSb = CreateObject('Chilkat.StringBuilder')
lnCrlfLineEnding = 1

FOR i = 0 TO 10
    loSb.AppendLine("This is a test.",lnCrlfLineEnding)
NEXT

lcBase64_rsa_sig = "gWgpEXQqvXN6wh0MuFXPiw2xCb8cnmdizBT1TD1Tpm2GlJ8gnD59DGSj35GGXk1tM+mCOvMa2uW/9gmz8p6A90JLbn918i/2wKGvcde4wXnzPO7JADSNn2UwYzf3rp4/q/JrHv1GZETRJhABSFqTxOgdmdbEJQE/zijOSctCtQAM2CTb6t2BO8uHKSSUAwPH2cbeWxqsaVRLT4ruk5nZOxhoLgLMSjupiSzbE8zSTkkFOEHD+Mbb2xwg85AI0E4DsUnp+hLwwtS0blesgSyvtBY8oJODJeFcJsR7JDOTPdzHQHgJRl/2A4ij5xT91TpXy7ok43jhT6O9j7Q3qrafIQ=="

* Get the public key to be used for signature verification.
loPubKey = CreateObject('Chilkat.PublicKey')
lnSuccess = loPubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
IF (lnSuccess = 0) THEN
    ? loPubKey.LastErrorText
    RELEASE loSb
    RELEASE loPubKey
    CANCEL
ENDIF

loRsa = CreateObject('Chilkat.Rsa')
lnSuccess = loRsa.UsePublicKey(loPubKey)
IF (lnSuccess = 0) THEN
    ? loRsa.LastErrorText
    RELEASE loSb
    RELEASE loPubKey
    RELEASE loRsa
    CANCEL
ENDIF

* Verify the string against the signature.
* We signed the utf-8 byte representation of the string, so we must indicate
* to also validate against the utf-8 byte representation.
loRsa.Charset = "utf-8"
loRsa.EncodingMode = "base64"
lcSignedString = loSb.GetAsString()
lnSuccess = loRsa.VerifyStringENC(lcSignedString,"sha256",lcBase64_rsa_sig)

IF (lnSuccess = 0) THEN
    ? loRsa.LastErrorText
    ? "Signature invalid."
ELSE
    ? "Signature valid."
ENDIF

RELEASE loSb
RELEASE loPubKey
RELEASE loRsa