java - How does one convert a public EC code point and curve name into a PublicKey?

Question

I have two 32 byte long byte arrays representing the X and Y values for an EC Public Key. I know that the curve is the named curve "prime256v1".

How can I turn that into a Java PublicKey object?

The JCE appears to provide no facilities whatsoever to use named curves.

Bouncycastle's example code does not appear to compile with any version of bouncycastle I can find.

WTF?

Answer 1

It turns out that there is, in fact, another way to do this. The AlgorithmParameters class can apparently be used to translate an ECGenParameterSpec, with a named curve, into an ECParameterSpec object that you can use with a KeyFactory to generate a PublicKey object:

            ECPoint pubPoint = new ECPoint(new BigInteger(1, x),new BigInteger(1, y));
            AlgorithmParameters parameters = AlgorithmParameters.getInstance("EC", "SunEC");
            parameters.init(new ECGenParameterSpec("secp256r1"));
            ECParameterSpec ecParameters = parameters.getParameterSpec(ECParameterSpec.class);
            ECPublicKeySpec pubSpec = new ECPublicKeySpec(pubPoint, ecParameters);
            KeyFactory kf = KeyFactory.getInstance("EC");
            return (ECPublicKey)kf.generatePublic(pubSpec);