(Lianja) RSA Sign Binary Data and Verify (Recover the Original Data)

Demonstrates how to RSA sign binary data and then verify/recover the original data.

Note: This example uses methods introduced in Chilkat v9.5.0.77.

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// 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 <> .T.) then
    ? loPrivKey.LastErrorText
    release loPrivKey
    return
endif

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

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

// If successful, the contents of bd are replaced with the RSA signature.
llSuccess = loRsa.OpenSslSignBd(loBd)
if (llSuccess <> .T.) then
    ? loRsa.LastErrorText
    release loPrivKey
    release loRsa
    release loBd
    return
endif

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

// ------------------------------------------
// Get the public key from the private key
loPubKey = loPrivKey.GetPublicKey()

// Verify the signature and extract the original data.
loRsa2 = createobject("CkRsa")
loRsa2.ImportPublicKeyObj(loPubKey)

llBVerified = loRsa2.OpenSslVerifyBd(loBd)
? "signature verified: " + str(llBVerified)

// Show the original data:
? "original data: " + loBd.GetEncoded("hex")

release loPubKey


release loPrivKey
release loRsa
release loBd
release loRsa2