(C#) RSA Encrypt/Decrypt Bytes

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Demonstrates how to RSA encrypt and decrypt byte data.

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// The RSA public key is used for encryption, and the private key for decryption.

// The public key's role is to make encryption accessible to anyone while ensuring that
// only the private key holder can decrypt the messages.
// The public key is designed to be widely distributed so anyone can use it to encrypt messages
// intended for the owner of the private key.

// Load our 2048-bit RSA public key.
Chilkat.PublicKey pubKey = new Chilkat.PublicKey();
// In all Chilkat methods expecting a path, you pass either absolute or relative paths.
bool success = pubKey.LoadFromFile("qa_data/rsaKeys/myTestRsaPublic.pem");
if (success == false) {
    Debug.WriteLine(pubKey.LastErrorText);
    return;
}

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

// Tell RSA to use the public key.
rsa.ImportPublicKeyObj(pubKey);

// RSA encryption is for small amounts of data, on the order of 200 bytes or less.
// The maximum number of bytes that can be RSA encrypted depends
// on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
// For specific limits, see: RSA Encryption Maximum Number of Bytes

// A typical use for RSA is to encrypt symmetric encryption keys, such as an AES key.
Chilkat.Prng prng = new Chilkat.Prng();
byte[] keyBytes = null;
keyBytes = prng.GenRandomBytes(32);

byte[] encBytes = null;
encBytes = rsa.EncryptBytes(keyBytes,false);

// ------------------------------------------------------------------------------------------------------------------------
// Let's decrypt, which requires the matching private key...

// Load the matching 2048-bit RSA private key.
Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();
string password = "secret";
success = privKey.LoadAnyFormatFile("qa_data/rsaKeys/myTestRsaPrivate.pem",password);
if (success == false) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

// Tell the RSA object to use the private key.
rsa.ImportPrivateKeyObj(privKey);

byte[] decBytes = null;
decBytes = rsa.DecryptBytes(encBytes,true);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

Debug.WriteLine("Success.");