Crypto.java

package com.duosecurity.duokit.crypto;

import org.spongycastle.util.encoders.Base64;
import org.spongycastle.util.encoders.Hex;

import java.io.UnsupportedEncodingException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PublicKey;
import java.security.Security;
import java.security.spec.X509EncodedKeySpec;

public class Crypto {

    private static final String PROVIDER = "SC";

    private static final String KEGEN_ALG = "ECDH";

    private static Crypto instance;

    static {
        Security.addProvider(new org.spongycastle.jce.provider.BouncyCastleProvider());
    }

    private KeyFactory kf;

    public static synchronized Crypto getInstance() {
        if (instance == null) {
            instance = new Crypto();
        }

        return instance;
    }

    private Crypto() {
        try {
            kf = KeyFactory.getInstance(KEGEN_ALG, PROVIDER);
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        } catch (NoSuchProviderException e) {
            throw new RuntimeException(e);
        }
    }

    public static String hex(byte[] bytes) {
        try {
            return new String(Hex.encode(bytes), "ASCII");
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
    }

    public static byte[] base64Decode(String str) {
        return Base64.decode(str);
    }

    public synchronized PublicKey readPublicKey(String keyStr) throws Exception {
        X509EncodedKeySpec x509ks = new X509EncodedKeySpec(
                Base64.decode(keyStr));
        return kf.generatePublic(x509ks);
    }
}