(Lianja) RSA Hash Binary Data and Sign (and Verify)

Demonstrates how to sign the hash of binary data. Also demonstrates how to verify the RSA signature.

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

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llSuccess = .F.

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

// Load an RSA private key for signing.
loPrivKey = createobject("CkPrivateKey")
llSuccess = loPrivKey.LoadEncryptedPemFile("qa_data/pem/rsa_passwd.pem","passwd")
if (llSuccess = .F.) then
    ? loPrivKey.LastErrorText
    release loPrivKey
    return
endif

loRsa = createobject("CkRsa")
loRsa.UsePrivateKey(loPrivKey)

// We have some binary data (in hex) to sign
lcOriginalData = "0102030405060708090A"
loBdData = createobject("CkBinData")
loBdData.AppendEncoded(lcOriginalData,"hex")

// Hash (SHA-256) and sign the hash:
loBdSignature = createobject("CkBinData")
llSuccess = loRsa.SignBd(loBdData,"sha256",loBdSignature)
if (llSuccess = .F.) then
    ? loRsa.LastErrorText
    release loPrivKey
    release loRsa
    release loBdData
    release loBdSignature
    return
endif

// Show the RSA signature in base64
? loBdSignature.GetEncoded("base64")

// ------------------------------------------
// Get the public key from the private key
loPubKey = createobject("CkPublicKey")
loPrivKey.ToPublicKey(loPubKey)

// Verify the signature..
loRsa2 = createobject("CkRsa")
loRsa2.UsePublicKey(loPubKey)

llBVerified = loRsa2.VerifyBd(loBdData,"sha256",loBdSignature)
? "signature verified: " + str(llBVerified)


release loPrivKey
release loRsa
release loBdData
release loBdSignature
release loPubKey
release loRsa2