RSA Encrypt and Decrypt Credit Card Numbers

Perl 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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use chilkat();

$rsa = new chilkat::CkRsa();

$success = $rsa->UnlockComponent("Anything for 30-day trial");
if ($success != 1) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

$key = new chilkat::CkPrivateKey();

#  Load an RSA private key from a PKCS8 file:
$success = $key->LoadPkcs8File("rsaPrivateKey.p8");
if ($success != 1) {
    print $key->lastErrorText() . "\n";
    exit;
}

#  Get the key as XML:

$keyXml = $key->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.
$success = $rsa->ImportPublicKey($keyXml);
if ($success != 1) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

#  Encrypt a VISA credit card number:
#  1234-5678-0000-9999
$ccNumber = "1234567800009999";

$usePrivateKey = 0;
$rsa->put_EncodingMode("base64");
$encryptedStr = $rsa->encryptStringENC($ccNumber,$usePrivateKey);
print "Encrypted:" . "\r\n";
print $encryptedStr . "\r\n";

#  Now decrypt:
$rsaDecryptor = new chilkat::CkRsa();

$rsaDecryptor->put_EncodingMode("base64");
$rsaDecryptor->ImportPrivateKey($keyXml);

$usePrivateKey = 1;
$decryptedStr = $rsaDecryptor->decryptStringENC($encryptedStr,$usePrivateKey);

print "Decrypted:" . "\r\n";
print $decryptedStr . "\r\n";

#  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.