(Lianja) RSA Encrypt and Decrypt Credit Card Numbers

Lianja sample code to RSA public-key encrypt and decrypt credit card numbers. The RSA key is loaded from an unencrypted PKCS8 file. Chilkat provides many ways of setting the key -- loading from both encrypted and unencrypted PEM, PKCS8, DER, PVK, etc. Keys may be loaded from files or in-memory representations. (The RSA component also provides the ability to generate RSA keys.)

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

loRsa = createobject("CkRsa")

loKey = createobject("CkPrivateKey")

// Load an RSA private key from a file:
llSuccess = loKey.LoadAnyFormatFile("rsaPrivateKey.key","")
if (llSuccess <> .T.) then
    ? loKey.LastErrorText
    release loRsa
    release loKey
    return
endif

// Get the key as XML:

lcKeyXml = loKey.GetXml()

// We'll encrypt with the public key and decrypt with the private
// key.  (It's also possible to do the reverse.)
// Note: An RSA private key is composed of different parts internally: modulus, exponent, P, Q, etc.
// An RSA public-key is a sub-set of the private key.
// Therefore, when you have a private key, you really have
// both public and private keys.
llSuccess = loRsa.ImportPublicKey(lcKeyXml)
if (llSuccess <> .T.) then
    ? loRsa.LastErrorText
    release loRsa
    release loKey
    return
endif

// Encrypt a VISA credit card number:
// 1234-5678-0000-9999
lcCcNumber = "1234567800009999"

llUsePrivateKey = .F.
loRsa.EncodingMode = "base64"
lcEncryptedStr = loRsa.EncryptStringENC(lcCcNumber,llUsePrivateKey)
? "Encrypted:"
? lcEncryptedStr

// Now decrypt:
loRsaDecryptor = createobject("CkRsa")

loRsaDecryptor.EncodingMode = "base64"
llSuccess = loRsaDecryptor.ImportPrivateKey(lcKeyXml)

llUsePrivateKey = .T.
lcDecryptedStr = loRsaDecryptor.DecryptStringENC(lcEncryptedStr,llUsePrivateKey)

? "Decrypted:"
? lcDecryptedStr

// Important: RSA encryption should only be used to encrypt small amounts of data.
// It is typically used for encrypting symmetric encryption
// keys such that a symmetric encryption algorithm, such as 
// AES is then used to encrypt/decrypt bulk data


release loRsa
release loKey
release loRsaDecryptor