EdsaSigner.java

package com.beowulfe.hap.impl.crypto;

import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.Signature;
import java.security.SignatureException;

import net.i2p.crypto.eddsa.EdDSAEngine;
import net.i2p.crypto.eddsa.EdDSAPrivateKey;
import net.i2p.crypto.eddsa.EdDSAPublicKey;
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;

public class EdsaSigner {
	
	private final EdDSAPublicKey publicKey;
	private final EdDSAPrivateKey privateKey;

	public EdsaSigner(byte[] privateKeyBytes) {
		EdDSAParameterSpec spec = EdDSANamedCurveTable.getByName("ed25519-sha-512");
		EdDSAPrivateKeySpec privateKeySpec = new EdDSAPrivateKeySpec(privateKeyBytes, spec);
		EdDSAPublicKeySpec pubKeySpec = new EdDSAPublicKeySpec(privateKeySpec.getA(), spec);
		publicKey = new EdDSAPublicKey(pubKeySpec);
		privateKey = new EdDSAPrivateKey(privateKeySpec);
	}
	
	public byte[] getPublicKey() {
		return publicKey.getAbyte();
	}
	
	public byte[] sign(byte[] material) throws NoSuchAlgorithmException, InvalidKeyException,
			SignatureException {
		Signature sgr = new EdDSAEngine(MessageDigest.getInstance("SHA-512"));
		sgr.initSign(privateKey);
		sgr.update(material);
		return sgr.sign();
	}

}