(C#) Create JWS Using Private Key on a Smart Card

See more JSON Web Signatures (JWS) Examples

Note: This example requires Chilkat v11.5.0 or greater.

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bool success = false;

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

// Load the certificate from a smart card.
Chilkat.Cert cert = new Chilkat.Cert();

// Set the smarcard PIN prior to loading.
cert.SmartCardPin = "123456";

// Detect the connected smartcard or USB security token and load the default certificate.
success = cert.LoadFromSmartcard("");
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

// Note: Chilkat provides many different ways to load a certificate from a smartcard or USB token,
// such as selecting a certificate if the card contains multiple certificates with private keys,
// or working with lower-level PKCS11 or ScMinidriver API's (both of which Chilkat provides).

// Create the JWS Protected Header
Chilkat.JsonObject jwsProtHdr = new Chilkat.JsonObject();

if (cert.IsEcdsa() == true) {
    jwsProtHdr.AppendString("alg","ES256");
}
else {
    jwsProtHdr.AppendString("alg","RS256");
}

Chilkat.Jws jws = new Chilkat.Jws();

// Set the protected header:
int signatureIndex = 0;
jws.SetProtectedHeader(signatureIndex,jwsProtHdr);

// Provide the private key via the certificate.
// This requires Chilkat v11.5.0 or greater.
jws.SetSigningCert(signatureIndex,cert);

// Set the payload.
bool bIncludeBom = false;
string payloadStr = "In our village, folks say God crumbles up the old moon into stars.";
jws.SetPayload(payloadStr,"utf-8",bIncludeBom);

// Create the JWS
// By default, the compact serialization is used.
string jwsCompact = jws.CreateJws();
if (jws.LastMethodSuccess == false) {
    Debug.WriteLine(jws.LastErrorText);
    return;
}

Debug.WriteLine("JWS: " + jwsCompact);

// sample output:
// JWS: eyJhbGciOiJQUzI1NiJ9.SW4gb3VyIHZpbGxhZ2UsIGZvbGtzIHNheSBHb2QgY3J1bWJsZXMgdXAgdGhlIG9sZCBtb29uIGludG8gc3RhcnMu.TRWhwRo5dMv9-8OzrInfJTwmUGYgjLfHk8lqF072ND-FmLWEBnUTOpY8oJXp8FdWw2SalbdOeNlrtlJjwk4XK8Ql2iJ_2qMCtxsvLPhKBOqFoAF4aBvTOEDVJDxf0DaBSiydEEtfTVV2iwBcjWabu5J2XieR5y7QZQtuHsn7T3qKBvCcCejN3Y2oqAT3qMHvu1fTms1r_91wBn_K7Wjd9UkZ1n02qQcUHJznR_OF2BgN7_KWIDAF9ZS9keoju2NPpPelO4yxa2XUPnehY3G7dHKoCxUEQR4d2Xc5voqDASTVCDqQS4PVOZdvT3Ein6-SanAlCwbWBbkvT8g6-5PImQ

// Now load the JWS, validate, and recover the original text.
Chilkat.Jws jws2 = new Chilkat.Jws();

// Load the JWS.
success = jws2.LoadJws(jwsCompact);

Chilkat.PublicKey pubKey = new Chilkat.PublicKey();
cert.GetPublicKey(pubKey);

// Set the public key used for validation.
signatureIndex = 0;
jws2.SetPublicKey(signatureIndex,pubKey);

// Validate the 1st (and only) signature at index 0..
int v = jws2.Validate(signatureIndex);
if (v < 0) {
    // Perhaps Chilkat was not unlocked or the trial expired..
    Debug.WriteLine("Method call failed for some other reason.");
    Debug.WriteLine(jws2.LastErrorText);
    return;
}

if (v == 0) {
    Debug.WriteLine("Invalid signature.  The key was incorrect, the JWS was invalid, or both.");
    return;
}

// If we get here, the signature was validated..
Debug.WriteLine("Signature validated.");

// Recover the original content:
Debug.WriteLine(jws2.GetPayload("utf-8"));

// Examine the protected header:

Chilkat.JsonObject joseHeader = new Chilkat.JsonObject();
success = jws2.GetProtectedH(signatureIndex,joseHeader);
if (success == false) {
    Debug.WriteLine(jws2.LastErrorText);
    return;
}

joseHeader.EmitCompact = false;

Debug.WriteLine("Protected (JOSE) header:");
Debug.WriteLine(joseHeader.Emit());

// Output:

// 	Signature validated.
// 	In our village, folks say God crumbles up the old moon into stars.
// 	Protected (JOSE) header:
// 	{ 
// 	  "alg": "RS256"
// 	}