(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.)

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL lnSuccess
LOCAL loRsa
LOCAL loPrivKey
LOCAL loPubKey
LOCAL lcCcNumber
LOCAL lnUsePrivateKey
LOCAL lcEncryptedStr
LOCAL loRsaDecryptor
LOCAL lcDecryptedStr

lnSuccess = 0

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

loRsa = CreateObject('Chilkat.Rsa')

loPrivKey = CreateObject('Chilkat.PrivateKey')

* Load an RSA private key from a file:
lnSuccess = loPrivKey.LoadAnyFormatFile("rsaPrivateKey.key","")
IF (lnSuccess = 0) THEN
    ? loPrivKey.LastErrorText
    RELEASE loRsa
    RELEASE loPrivKey
    CANCEL
ENDIF

* Get the public part of the private key.
loPubKey = CreateObject('Chilkat.PublicKey')
loPrivKey.ToPublicKey(loPubKey)

lnSuccess = loRsa.UsePublicKey(loPubKey)
IF (lnSuccess = 0) THEN
    ? loRsa.LastErrorText
    RELEASE loRsa
    RELEASE loPrivKey
    RELEASE loPubKey
    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.Rsa')

loRsaDecryptor.EncodingMode = "base64"
loRsaDecryptor.UsePrivateKey(loPrivKey)

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 loPrivKey
RELEASE loPubKey
RELEASE loRsaDecryptor