Rsa.java

/*
 * Copyright (C) 2010 The MobileSecurePay Project
 * All right reserved.
 * author: shiqun.shi@alipay.com
 */

package com.wise.alipay;

import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.Cipher;

import android.util.Log;

public class Rsa {

	private static final String ALGORITHM = "RSA";

	/**
	 * @param algorithm
	 * @param ins
	 * @return
	 * @throws NoSuchAlgorithmException
	 * @throws AlipayException
	 */
	private static PublicKey getPublicKeyFromX509(String algorithm,
			String bysKey) throws NoSuchAlgorithmException, Exception {
		byte[] decodedKey = Base64.decode(bysKey);
		X509EncodedKeySpec x509 = new X509EncodedKeySpec(decodedKey);

		KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
		return keyFactory.generatePublic(x509);
	}

	public static String encrypt(String content, String key) {
		try {
			PublicKey pubkey = getPublicKeyFromX509(ALGORITHM, key);

			Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
			cipher.init(Cipher.ENCRYPT_MODE, pubkey);

			byte plaintext[] = content.getBytes("UTF-8");
			byte[] output = cipher.doFinal(plaintext);

			String s = new String(Base64.encode(output));

			return s;

		} catch (Exception e) {
			e.printStackTrace();
			return null;
		}
	}

	public static final String SIGN_ALGORITHMS = "SHA1WithRSA";

	public static String sign(String content, String privateKey) {
		String charset = "UTF-8";
		try {
			PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(
					Base64.decode(privateKey));
			KeyFactory keyf = KeyFactory.getInstance("RSA");
			PrivateKey priKey = keyf.generatePrivate(priPKCS8);

			java.security.Signature signature = java.security.Signature
					.getInstance(SIGN_ALGORITHMS);

			signature.initSign(priKey);
			signature.update(content.getBytes(charset));

			byte[] signed = signature.sign();

			return Base64.encode(signed);
		} catch (Exception e) {
			e.printStackTrace();
		}

		return null;
	}
	public static String getMD5(String content) {
		String s = null;
		char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
				'a', 'b', 'c', 'd', 'e', 'f' };
		try {
			java.security.MessageDigest md = java.security.MessageDigest
					.getInstance("MD5");
			md.update(content.getBytes());
			byte tmp[] = md.digest();
			char str[] = new char[16 * 2];
			int k = 0;
			for (int i = 0; i < 16; i++) {
				byte byte0 = tmp[i];
				str[k++] = hexDigits[byte0 >>> 4 & 0xf];
				str[k++] = hexDigits[byte0 & 0xf];
			}
			s = new String(str);

		} catch (Exception e) {
			e.printStackTrace();
		}
		return s;
	}
	public static boolean doCheck(String content, String sign, String publicKey) {
		try {
			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
			byte[] encodedKey = Base64.decode(publicKey);
			PublicKey pubKey = keyFactory
					.generatePublic(new X509EncodedKeySpec(encodedKey));

			java.security.Signature signature = java.security.Signature
					.getInstance(SIGN_ALGORITHMS);

			signature.initVerify(pubKey);
			signature.update(content.getBytes("utf-8"));
			Log.i("Result", "content :   "+content);
			Log.i("Result", "sign:   "+sign);
			boolean bverify = signature.verify(Base64.decode(sign));
			Log.i("Result","bverify = " + bverify);
			return bverify;
		} catch (Exception e) {
			e.printStackTrace();
		}

		return false;
	}
}