(Swift 3,4,5...) 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 Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    let pubKey = CkoPublicKey()!

    // 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...

    let sb = CkoStringBuilder()!
    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..
    var success: Bool = pubKey.load(from: sb.getAsString())
    if success != true {
        print("\(pubKey.lastErrorText!)")
        return
    }

    // Get the JWK thumbprint (using SHA256)
    print("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.load(from: sb.getAsString())
    if success != true {
        print("\(pubKey.lastErrorText!)")
        return
    }

    // Get the JWK thumbprint (using SHA256)
    print("JWK thumbprint: \(pubKey.getJwkThumbprint("SHA256")!)")

    // Output:
    // JWK thumbprint: 8fm8079s3nu4FLV_7dVJoJ69A8XCXn7Za2mtaWCnxR4

}