(C#) Yubikey RSA Encrypt/Decrypt

See more RSA Examples

Note: RSA encryption uses the public key, which is freely exportable and does not need to occur on the token/smartcard.

Note: This example requires Chilkat v10.1.3 or greater.

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// This example assumes you have a certificate with private key on the Yubikey token.
// When doing simple RSA encryption/decryption, we don't actually need the certificate,
// but we'll be using the private key associated with the certificate.
// 
// The sensitive/secret material that needs to be kept private is the private key.
// The certificate itself and the public key can be freely shared.
// 

// We're going to encrypt and decrypt 32-bytes of data.
Chilkat.BinData bd = new Chilkat.BinData();
bool success = bd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex");
success = bd.AppendEncoded("000102030405060708090A0B0C0D0E0F","hex");

// Let's get the desired cert.
// For this example, a self-signed certificate with a 2048-bit RSA key was generated in slot 9A.
Chilkat.Cert cert = new Chilkat.Cert();

// Force Chilkat to use PKCS11 over ScMinidriver (if on Windows) and Apple Keychain (if on MacOS)
cert.UncommonOptions = "NoScMinidriver,NoAppleKeychain";

cert.SmartCardPin = "123456";

success = cert.LoadFromSmartcard("cn=chilkat_test_2048");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// RSA encrypt using the public key.
Chilkat.Rsa rsa = new Chilkat.Rsa();

// Provide the RSA object with the certificate on the Yubkey.
success = rsa.SetX509Cert(cert,true);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// RSA encrypt using the public key.
bool usePrivateKey = false;
success = rsa.EncryptBd(bd,usePrivateKey);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

Debug.WriteLine("RSA Encrypted Output in Hex:");
Debug.WriteLine(bd.GetEncoded("hex"));

// Now let's decrypt, using the private key on the Yubikey.
usePrivateKey = true;
success = rsa.DecryptBd(bd,usePrivateKey);
if (success == false) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

Debug.WriteLine("RSA Decrypted Output in Hex:");
Debug.WriteLine(bd.GetEncoded("hex"));