(Lianja) RSA Signature/Verify with .key and .cer

See more RSA Examples

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature.

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

loPrivKey = createobject("CkPrivateKey")

// Load the private key from an RSA .key file:
llSuccess = loPrivKey.LoadPemFile("privateKey.key")
if (llSuccess <> .T.) then
    ? loPrivKey.LastErrorText
    release loPrivKey
    return
endif

// Get the private key in XML format:
lcPrivKeyXml = loPrivKey.GetXml()

loRsa = createobject("CkRsa")

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

// Create the signature as a hex string:
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", "sha256", "sha384",
// "sha512", and "md5".
lcHexSig = loRsa.SignStringENC(lcStrData,"sha-1")

? lcHexSig

// Load a digital certificate from a .cer file:
loCert = createobject("CkCert")

llSuccess = loCert.LoadFromFile("myCert.cer")
if (llSuccess <> .T.) then
    ? loCert.LastErrorText
    release loPrivKey
    release loRsa
    release loCert
    return
endif

loPubKey = loCert.ExportPublicKey()

// Now verify using a separate instance of the RSA object:
loRsa2 = createobject("CkRsa")

// Import the public key into the RSA object:
llSuccess = loRsa2.ImportPublicKey(loPubKey.GetXml())
if (llSuccess <> .T.) then
    ? loRsa2.LastErrorText
    release loPrivKey
    release loRsa
    release loCert
    release loRsa2
    return
endif

release loPubKey

// The signature is a hex string, so make sure the EncodingMode is correct:
loRsa2.EncodingMode = "hex"

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

? "Success."


release loPrivKey
release loRsa
release loCert
release loRsa2