Lianja

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. Lianja

llSuccess = .F.

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

loSb = createobject("CkStringBuilder")
llCrlfLineEnding = .T.

for i = 0 to 10
    loSb.AppendLine("This is a test.",llCrlfLineEnding)
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("CkPublicKey")
llSuccess = loPubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
if (llSuccess = .F.) then
    ? loPubKey.LastErrorText
    release loSb
    release loPubKey
    return
endif

loRsa = createobject("CkRsa")
llSuccess = loRsa.UsePublicKey(loPubKey)
if (llSuccess = .F.) then
    ? loRsa.LastErrorText
    release loSb
    release loPubKey
    release loRsa
    return
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()
llSuccess = loRsa.VerifyStringENC(lcSignedString,"sha256",lcBase64_rsa_sig)

if (llSuccess = .F.) then
    ? loRsa.LastErrorText
    ? "Signature invalid."
else
    ? "Signature valid."
endif



release loSb
release loPubKey
release loRsa