(Lianja) RSA Sign with PKCS8 Encrypted Key

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it).

Chilkat Lianja Extension Download Chilkat Lianja Extension

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

loPkey = createobject("CkPrivateKey")

// Load the private key from an RSA PEM file:
llSuccess = loPkey.LoadPkcs8EncryptedFile("raul_privateKey.key","a0123456789")

// Get the private key in XML format:
lcPkeyXml = loPkey.GetXml()

loRsa = createobject("CkRsa")

// Import the private key into the RSA component:
llSuccess = loRsa.ImportPrivateKey(lcPkeyXml)
if (llSuccess <> .T.) then
    ? loRsa.LastErrorText
    release loPkey
    release loRsa
    return
endif

// This example will sign a string, and receive the signature
// in a hex-encoded string.  Therefore, set the encoding mode
// to "hex":
loRsa.EncodingMode = "hex"

lcStrData = "This is the string to be signed."

// Sign the string using the sha-1 hash algorithm.
// Other valid choices are "md2" and "md5".
lcHexSig = loRsa.SignStringENC(lcStrData,"sha-1")

? lcHexSig

// Now verify with the public key.
// This example shows how to use the public key from 
// a digital certificate (.cer file)
loCert = createobject("CkCert")
llSuccess = loCert.LoadFromFile("raul_publicKey.cer")
if (llSuccess <> .T.) then
    ? loCert.LastErrorText
    release loPkey
    release loRsa
    release loCert
    return
endif

loPubKey = loCert.ExportPublicKey()

// Get the private key in XML format:
lcPubKeyXml = loPubKey.GetXml()

loRsa2 = createobject("CkRsa")
llSuccess = loRsa2.ImportPublicKey(lcPubKeyXml)
if (llSuccess <> .T.) then
    ? loRsa2.LastErrorText
    release loPkey
    release loRsa
    release loCert
    release loRsa2
    return
endif

// Verify the signature against the original data:
loRsa2.EncodingMode = "hex"
llSuccess = loRsa2.VerifyStringENC(lcStrData,"sha-1",lcHexSig)
if (llSuccess <> .T.) then
    ? loRsa2.LastErrorText
    release loPkey
    release loRsa
    release loCert
    release loRsa2
    return
endif

? "Signature verified!"

// Verify with incorrect data:
llSuccess = loRsa2.VerifyStringENC("something else","sha-1",lcHexSig)
if (llSuccess <> .T.) then
    ? "Signature not verified! (which was expected in this case)"
else
    ? "Hmmm... that's not right..."
endif

release loPubKey


release loPkey
release loRsa
release loCert
release loRsa2