(Visual FoxPro) RSA Encrypt and Decrypt Credit Card Numbers

Visual FoxPro 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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LOCAL loRsa
LOCAL lnSuccess
LOCAL loKey
LOCAL lcKeyXml
LOCAL lcCcNumber
LOCAL lnUsePrivateKey
LOCAL lcEncryptedStr
LOCAL loRsaDecryptor
LOCAL lcDecryptedStr

loRsa = CreateObject('Chilkat_9_5_0.Rsa')

lnSuccess = loRsa.UnlockComponent("Anything for 30-day trial")
IF (lnSuccess <> 1) THEN
    ? loRsa.LastErrorText
    RELEASE loRsa
    CANCEL
ENDIF

loKey = CreateObject('Chilkat_9_5_0.PrivateKey')

*  Load an RSA private key from a PKCS8 file:
lnSuccess = loKey.LoadPkcs8File("rsaPrivateKey.p8")
IF (lnSuccess <> 1) THEN
    ? loKey.LastErrorText
    RELEASE loRsa
    RELEASE loKey
    CANCEL
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.
lnSuccess = loRsa.ImportPublicKey(lcKeyXml)
IF (lnSuccess <> 1) THEN
    ? loRsa.LastErrorText
    RELEASE loRsa
    RELEASE loKey
    CANCEL
ENDIF

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

lnUsePrivateKey = 0
loRsa.EncodingMode = "base64"
lcEncryptedStr = loRsa.EncryptStringENC(lcCcNumber,lnUsePrivateKey)
? "Encrypted:"
? lcEncryptedStr

*  Now decrypt:
loRsaDecryptor = CreateObject('Chilkat_9_5_0.Rsa')

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

lnUsePrivateKey = 1
lcDecryptedStr = loRsaDecryptor.DecryptStringENC(lcEncryptedStr,lnUsePrivateKey)

? "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