(C# UWP/WinRT) Compute JWK Thumbprint for RSA and EC Public Keys

Demonstrates how to compute a JSON Web Key thumbprint for a public key (RSA or ECC).

Note: This example requires Chilkat v9.5.0.66 or greater.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

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

// A public key can be loaded from any format (binary DER, PEM, etc.)
// This example will load the public keys from JWK format, 
// and will then compute the JWK thumbprint.

// First do it for an RSA public key...

Chilkat.StringBuilder sb = new Chilkat.StringBuilder();
sb.Append("{");
sb.Append("\"kty\": \"RSA\",");
sb.Append("\"n\": \"0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAt");
sb.Append("VT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMstn6");
sb.Append("4tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FD");
sb.Append("W2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n9");
sb.Append("1CbOpbISD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINH");
sb.Append("aQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw\",");
sb.Append("\"e\": \"AQAB\",");
sb.Append("\"alg\": \"RS256\",");
sb.Append("\"kid\": \"2011-04-29\"");
sb.Append("}");

// The JWK format is automatically detected..
bool success = pubKey.LoadFromString(sb.GetAsString());
if (success != true) {
    Debug.WriteLine(pubKey.LastErrorText);
    return;
}

// Get the JWK thumbprint (using SHA256)
Debug.WriteLine("JWK thumbprint: " + pubKey.GetJwkThumbprint("SHA256"));

// Output:
// JWK thumbprint: NzbLsXh8uDCcd-6MNwXF4W_7noWXFZAfHkxZsRGC9Xs

// --------------------------------------------------------------
// Now let's do an EC public key:
sb.Clear();
sb.Append("{ ");
sb.Append("  \"kty\": \"EC\",");
sb.Append("  \"crv\": \"P-256\",");
sb.Append("  \"x\": \"tDeeYABgKEAbWicYPCEEI8sP4SRIhHKcHDW7VqrB4LA\",");
sb.Append("  \"y\": \"J08HOoIZ0rX2Me3bNFZUltfxIk1Hrc8FsLu8VaSxsMI\"");
sb.Append("}");

success = pubKey.LoadFromString(sb.GetAsString());
if (success != true) {
    Debug.WriteLine(pubKey.LastErrorText);
    return;
}

// Get the JWK thumbprint (using SHA256)
Debug.WriteLine("JWK thumbprint: " + pubKey.GetJwkThumbprint("SHA256"));

// Output:
// JWK thumbprint: 8fm8079s3nu4FLV_7dVJoJ69A8XCXn7Za2mtaWCnxR4