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/**
* EdDSA-Java by str4d
*
* To the extent possible under law, the person who associated CC0 with
* EdDSA-Java has waived all copyright and related or neighboring rights
* to EdDSA-Java.
*
* You should have received a copy of the CC0 legalcode along with this
* work. If not, see <https://creativecommons.org/publicdomain/zero/1.0/>.
*
*/
package net.i2p.crypto.eddsa;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidParameterException;
import java.security.KeyPair;
import java.security.KeyPairGeneratorSpi;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;
import java.util.Hashtable;
import net.i2p.crypto.eddsa.spec.EdDSAGenParameterSpec;
import net.i2p.crypto.eddsa.spec.EdDSANamedCurveSpec;
import net.i2p.crypto.eddsa.spec.EdDSANamedCurveTable;
import net.i2p.crypto.eddsa.spec.EdDSAParameterSpec;
import net.i2p.crypto.eddsa.spec.EdDSAPrivateKeySpec;
import net.i2p.crypto.eddsa.spec.EdDSAPublicKeySpec;
/**
* Default keysize is 256 (Ed25519)
*/
public final class KeyPairGenerator extends KeyPairGeneratorSpi {
private static final int DEFAULT_KEYSIZE = 256;
private EdDSAParameterSpec edParams;
private SecureRandom random;
private boolean initialized;
private static final Hashtable<Integer, AlgorithmParameterSpec> edParameters;
static {
edParameters = new Hashtable<Integer, AlgorithmParameterSpec>();
edParameters.put(Integer.valueOf(256), new EdDSAGenParameterSpec(EdDSANamedCurveTable.ED_25519));
}
public void initialize(int keysize, SecureRandom random) {
AlgorithmParameterSpec edParams = edParameters.get(Integer.valueOf(keysize));
if (edParams == null)
throw new InvalidParameterException("unknown key type.");
try {
initialize(edParams, random);
} catch (InvalidAlgorithmParameterException e) {
throw new InvalidParameterException("key type not configurable.");
}
}
@Override
public void initialize(AlgorithmParameterSpec params, SecureRandom random) throws InvalidAlgorithmParameterException {
if (params instanceof EdDSAParameterSpec) {
edParams = (EdDSAParameterSpec) params;
} else if (params instanceof EdDSAGenParameterSpec) {
edParams = createNamedCurveSpec(((EdDSAGenParameterSpec) params).getName());
} else
throw new InvalidAlgorithmParameterException("parameter object not a EdDSAParameterSpec");
this.random = random;
initialized = true;
}
public KeyPair generateKeyPair() {
if (!initialized)
initialize(DEFAULT_KEYSIZE, new SecureRandom());
byte[] seed = new byte[edParams.getCurve().getField().getb()/8];
random.nextBytes(seed);
EdDSAPrivateKeySpec privKey = new EdDSAPrivateKeySpec(seed, edParams);
EdDSAPublicKeySpec pubKey = new EdDSAPublicKeySpec(privKey.getA(), edParams);
return new KeyPair(new EdDSAPublicKey(pubKey), new EdDSAPrivateKey(privKey));
}
/**
* Create an EdDSANamedCurveSpec from the provided curve name. The current
* implementation fetches the pre-created curve spec from a table.
* @param curveName the EdDSA named curve.
* @return the specification for the named curve.
* @throws InvalidAlgorithmParameterException if the named curve is unknown.
*/
protected EdDSANamedCurveSpec createNamedCurveSpec(String curveName) throws InvalidAlgorithmParameterException {
EdDSANamedCurveSpec spec = EdDSANamedCurveTable.getByName(curveName);
if (spec == null) {
throw new InvalidAlgorithmParameterException("unknown curve name: " + curveName);
}
return spec;
}
}
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