RSA Encrypt and Decrypt Strings

Download: Chilkat .NET Assemblies

C# sample code to RSA public-key encrypt and decrypt strings using public and private keys.

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

bool success;
success = rsa.UnlockComponent("Anything for 30-day trial");
if (success != true) {
    MessageBox.Show("RSA component unlock failed");
    return;
}

//  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 1024-bit key.  Chilkat RSA supports
//  key sizes ranging from 512 bits to 16384 bits.
success = rsa.GenerateKey(1024);
if (success != true) {
    MessageBox.Show(rsa.LastErrorText);
    return;
}

//  Keys are exported in XML format:
string publicKey;
publicKey = rsa.ExportPublicKey();
string privateKey;
privateKey = rsa.ExportPrivateKey();

string plainText;
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.  It's also possible to do the reverse.
rsaEncryptor.ImportPublicKey(publicKey);

bool usePrivateKey;
usePrivateKey = false;
string encryptedStr;
encryptedStr = rsaEncryptor.EncryptStringENC(plainText,usePrivateKey);
textBox1.Text += encryptedStr + "\r\n";
textBox1.Refresh();

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

rsaDecryptor.EncodingMode = "hex";
rsaDecryptor.ImportPrivateKey(privateKey);

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

textBox1.Text += decryptedStr + "\r\n";
textBox1.Refresh();