Class ToolElGamal

security/src/main/java/pro/tools/security/ToolElGamal.java:35–204

ElGamal安全编码组件 @author SeanDragon

 * @author SeanDragon
 */
public final class ToolElGamal {
    private ToolElGamal() {
        throw new UnsupportedOperationException("我是工具类，别初始化我。。。");
    }

    /**
     * 非对称加密密钥算法
     */
    public static final String KEY_ALGORITHM = "ElGamal";

    /**
     * 密钥长度
     * <p>
     * ElGamal算法默认密钥长度为1024 密钥长度范围在160位至16,384位不等。
     */
    private static final int KEY_SIZE = 256;

    /**
     * 公钥
     */
    private static final String PUBLIC_KEY = "ElGamalPublicKey";

    /**
     * 私钥
     */
    private static final String PRIVATE_KEY = "ElGamalPrivateKey";

    /**
     * 用私钥解密
     *
     * @param data
     *         待解密数据
     * @param key
     *         私钥
     *
     * @return byte[] 解密数据
     *
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] data, byte[] key) throws NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
        // 加入BouncyCastleProvider支持
        Security.addProvider(new BouncyCastleProvider());

        // 私钥材料转换
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);

        // 实例化密钥工厂
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

        // 生成私钥
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);

        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());

        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        return cipher.doFinal(data);