On 2013-10-08 17:41, Vincent Ryan wrote:
> Currently, there is no public API for named curves.
Since I wanted a source-compatible BC, JDK 6-7, and Android solution, I
ended-up using
public key samples instead:
ECParameterSpec spec = ((ECPublicKey) KeyFactory.getInstance
("EC").generatePublic (new X509EncodedKeySpec (sample_public_key))).getParams
();
https://code.google.com/p/openkeystore/source/browse/library/trunk/src/org/webpki/crypto/KeyAlgorithms.java
It is not pretty but since it is one-time op I can (probably) live with it.
Anders
>
> However you can generate named curves using the SunEC provider and the
> ECParameterSpec class.
> For example,
>
> AlgorithmParameters parameters =
> AlgorithmParameters.getInstance("EC", "SunEC");
> parameters.init(new ECGenParameterSpec("secp256r1"));
> ECParameterSpec ecParameters =
> parameters.getParameterSpec(ECParameterSpec.class);
>
> return KeyFactory.getInstance("EC", "SunEC").generatePublic(new
> ECPublicKeySpec(new ECPoint(x, y), ecParameters));
>
>
> It's not elegant but the list of supported named curves can be extracted from
> the AlgorithmParameters.EC SupportedCurves
> property. For example,
>
> String[] curves = Security.getProvider("SunEC")
> .getProperty("AlgorithmParameters.EC SupportedCurves")
> .split("\\|");
> for (String curve : curves) {
> System.out.println(curve.substring(1, curve.indexOf(",")));
> }
>
>
>
>
> On 8 Oct 2013, at 13:53, Anders Rundgren wrote:
>
>> If you have the X and Y points and the name of a public key you can create a
>> ECPublicKey using BouncyCastle.
>> I cannot find any counterpart in JDK 7. What am I missing?
>>
>> BC:
>>
>> return KeyFactory.getInstance ("EC").generatePublic (new ECPublicKeySpec
>> (new ECPoint (x, y), new ECNamedCurveSpec (name,...)));
>>
>> Cheers
>> Anders
>
