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.)

Download Chilkat RSA ActiveX

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

loRsa = CreateObject('Chilkat.Rsa')

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

loKey = CreateObject('Chilkat.PrivateKey')

*  Load an RSA private key from a PKCS8 file:
lnSuccess = loKey.LoadPkcs8File("rsaPrivateKey.p8")
IF (lnSuccess <> 1) THEN
    =MESSAGEBOX(loKey.LastErrorText)
    QUIT
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
    =MESSAGEBOX(loRsa.LastErrorText)
    QUIT
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.Rsa')

loRsaDecryptor.EncodingMode = "base64"
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.