(PHP Extension) RSA Encrypt and Decrypt Credit Card Numbers

PHP Extension 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.

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<?php

include("chilkat.php");

$success = false;

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

$rsa = new CkRsa();

$privKey = new CkPrivateKey();

// Load an RSA private key from a file:
$success = $privKey->LoadAnyFormatFile('rsaPrivateKey.key','');
if ($success == false) {
    print $privKey->lastErrorText() . "\n";
    exit;
}

// Get the public part of the private key.
$pubKey = new CkPublicKey();
$privKey->ToPublicKey($pubKey);

$success = $rsa->UsePublicKey($pubKey);
if ($success == false) {
    print $rsa->lastErrorText() . "\n";
    exit;
}

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

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

// Now decrypt:
$rsaDecryptor = new CkRsa();

$rsaDecryptor->put_EncodingMode('base64');
$rsaDecryptor->UsePrivateKey($privKey);

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

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

?>