C#

RSA Encrypt and Decrypt Strings

See more RSA Examples

_LANGUAGE_ sample code to RSA public-key encrypt and decrypt strings using public and private 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();

// This example also generates the public and private
// keys to be used in the RSA encryption.
// Normally, you would generate a key pair once,
// and distribute the public key to your partner.
// Anything encrypted with the public key can be
// decrypted with the private key.  The reverse is 
// also true: anything encrypted using the private
// key can be decrypted using the public key.

// Generate a 2048-bit key.  Chilkat RSA supports
// key sizes ranging from 512 bits to 4096 bits.
Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();
success = rsa.GenKey(2048,privKey);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

Chilkat.PublicKey pubKey = new Chilkat.PublicKey();
privKey.ToPublicKey(pubKey);

string plainText = "Encrypting and decrypting should be easy!";

// Start with a new RSA object to demonstrate that all we
// need are the keys previously exported:
Chilkat.Rsa rsaEncryptor = new Chilkat.Rsa();

// Encrypted output is always binary.  In this case, we want
// to encode the encrypted bytes in a printable string.
// Our choices are "hex", "base64", "url", "quoted-printable".
rsaEncryptor.EncodingMode = "hex";

// We'll encrypt with the public key and decrypt with the private
// key.
success = rsaEncryptor.UsePublicKey(pubKey);

bool usePrivateKey = false;
string encryptedStr = rsaEncryptor.EncryptStringENC(plainText,usePrivateKey);
Debug.WriteLine(encryptedStr);

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

rsaDecryptor.EncodingMode = "hex";
success = rsaDecryptor.UsePrivateKey(privKey);

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

Debug.WriteLine(decryptedStr);