Way to enumerate all elliptic curve names available in Java?

Question

Is there some way to enumerate all of the elliptic curve names that can be given to the ECGenParameterSpec constructor? Or do you have to just throw a big list of curve names at the wall and see which ones do or don't throw execeptions when you try to use them?

Answer 1

There is a better way to get hold of the list of supported curve names using supported APIs rather than reflection:

Security.getProviders("AlgorithmParameters.EC")[0]
    .getService("AlgorithmParameters", "EC").getAttribute("SupportedCurves");

In jshell (AdoptOpenJDK 11.0.1):

jshell> Security.getProviders("AlgorithmParameters.EC")[0]
    .getService("AlgorithmParameters", "EC").getAttribute("SupportedCurves")
$10 ==> "[secp112r1,1.3.132.0.6]|[secp112r2,1.3.132.0.7]|[secp128r1,1.3.132.0.28]|[secp128r2,1.3.132.0.29]|[secp160k1,1.3.132.0.9]|[secp160r1,1.3.132.0.8]|[secp160r2,1.3.132.0.30]|[secp192k1,1.3.132.0.31]|[secp192r1,NIST P-192,X9.62 prime192v1,1.2.840.10045.3.1.1]|[secp224k1,1.3.132.0.32]|[secp224r1,NIST P-224,1.3.132.0.33]|[secp256k1,1.3.132.0.10]|[secp256r1,NIST P-256,X9.62 prime256v1,1.2.840.10045.3.1.7]|[secp384r1,NIST P-384,1.3.132.0.34]|[secp521r1,NIST P-521,1.3.132.0.35]|[X9.62 prime192v2,1.2.840.10045.3.1.2]|[X9.62 prime192v3,1.2.840.10045.3.1.3]|[X9.62 prime239v1,1.2.840.10045.3.1.4]|[X9.62 prime239v2,1.2.840.10045.3.1.5]|[X9.62 prime239v3,1.2.840.10045 ... 840.10045.3.0.18]|[X9.62 c2tnb431r1,1.2.840.10045.3.0.20]|[brainpoolP160r1,1.3.36.3.3.2.8.1.1.1]|[brainpoolP192r1,1.3.36.3.3.2.8.1.1.3]|[brainpoolP224r1,1.3.36.3.3.2.8.1.1.5]|[brainpoolP256r1,1.3.36.3.3.2.8.1.1.7]|[brainpoolP320r1,1.3.36.3.3.2.8.1.1.9]|[brainpoolP384r1,1.3.36.3.3.2.8.1.1.11]|[brainpoolP512r1,1.3.36.3.3.2.8.1.1.13]"

You can then parse these entries.

However, there is now also the new "XEC" curves - X25519 and X448. As far as I am aware, these are only available as the two constants of NamedParameterSpec.

Answer 2

It depends very much on the provider you want to use. As stated by user69513, you'll want to consult the documentation. And there lies the most basic of problems.

For the SunEC provider, the documentation is nowhere to be found, nor are the sources available to the public. But by going through the exposed classes in sunec.jar we find the CurveDB class and a method getSupportedCurves. One could call that using reflection:

public static void main(String[] args) throws Exception {
    Method method = sun.security.ec.CurveDB.class.getDeclaredMethod("getSupportedCurves", null);
    method.setAccessible(true);
    Collection result = (Collection) method.invoke(null, null);
    for (Object object : result) {
        System.out.println(object);
    }
}

This provides you with full discolure:

secp112r1 (1.3.132.0.6)
secp112r2 (1.3.132.0.7)
secp128r1 (1.3.132.0.28)
secp128r2 (1.3.132.0.29)
secp160k1 (1.3.132.0.9)
secp160r1 (1.3.132.0.8)
secp160r2 (1.3.132.0.30)
secp192k1 (1.3.132.0.31)
secp192r1 [NIST P-192, X9.62 prime192v1] (1.2.840.10045.3.1.1)
secp224k1 (1.3.132.0.32)
secp224r1 [NIST P-224] (1.3.132.0.33)
secp256k1 (1.3.132.0.10)
secp256r1 [NIST P-256, X9.62 prime256v1] (1.2.840.10045.3.1.7)
secp384r1 [NIST P-384] (1.3.132.0.34)
secp521r1 [NIST P-521] (1.3.132.0.35)
X9.62 prime192v2 (1.2.840.10045.3.1.2)
X9.62 prime192v3 (1.2.840.10045.3.1.3)
X9.62 prime239v1 (1.2.840.10045.3.1.4)
X9.62 prime239v2 (1.2.840.10045.3.1.5)
X9.62 prime239v3 (1.2.840.10045.3.1.6)
sect113r1 (1.3.132.0.4)
sect113r2 (1.3.132.0.5)
sect131r1 (1.3.132.0.22)
sect131r2 (1.3.132.0.23)
sect163k1 [NIST K-163] (1.3.132.0.1)
sect163r1 (1.3.132.0.2)
sect163r2 [NIST B-163] (1.3.132.0.15)
sect193r1 (1.3.132.0.24)
sect193r2 (1.3.132.0.25)
sect233k1 [NIST K-233] (1.3.132.0.26)
sect233r1 [NIST B-233] (1.3.132.0.27)
sect239k1 (1.3.132.0.3)
sect283k1 [NIST K-283] (1.3.132.0.16)
sect283r1 [NIST B-283] (1.3.132.0.17)
sect409k1 [NIST K-409] (1.3.132.0.36)
sect409r1 [NIST B-409] (1.3.132.0.37)
sect571k1 [NIST K-571] (1.3.132.0.38)
sect571r1 [NIST B-571] (1.3.132.0.39)
X9.62 c2tnb191v1 (1.2.840.10045.3.0.5)
X9.62 c2tnb191v2 (1.2.840.10045.3.0.6)
X9.62 c2tnb191v3 (1.2.840.10045.3.0.7)
X9.62 c2tnb239v1 (1.2.840.10045.3.0.11)
X9.62 c2tnb239v2 (1.2.840.10045.3.0.12)
X9.62 c2tnb239v3 (1.2.840.10045.3.0.13)
X9.62 c2tnb359v1 (1.2.840.10045.3.0.18)
X9.62 c2tnb431r1 (1.2.840.10045.3.0.20)