C#

RSA Encrypt and Decrypt Credit Card Numbers

See more RSA Examples

_LANGUAGE_ 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.) C#

bool success = false;

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

Chilkat.Rsa rsa = new Chilkat.Rsa();

Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();

// Load an RSA private key from a file:
success = privKey.LoadAnyFormatFile("rsaPrivateKey.key","");
if (success == false) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

// Get the public part of the private key.
Chilkat.PublicKey pubKey = new Chilkat.PublicKey();
privKey.ToPublicKey(pubKey);

success = rsa.UsePublicKey(pubKey);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

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

bool usePrivateKey = false;
rsa.EncodingMode = "base64";
string encryptedStr = rsa.EncryptStringENC(ccNumber,usePrivateKey);
Debug.WriteLine("Encrypted:");
Debug.WriteLine(encryptedStr);

// Now decrypt:
Chilkat.Rsa rsaDecryptor = new Chilkat.Rsa();

rsaDecryptor.EncodingMode = "base64";
rsaDecryptor.UsePrivateKey(privKey);

usePrivateKey = true;
string decryptedStr = rsaDecryptor.DecryptStringENC(encryptedStr,usePrivateKey);

Debug.WriteLine("Decrypted:");
Debug.WriteLine(decryptedStr);

// 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