Encryption.java

package com.oc.mobilsecurity.datamanager;

import android.annotation.SuppressLint;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

@SuppressLint({ "DefaultLocale", "TrulyRandom" })
public class Encryption {

	/**
	 * ʹ��MD5ժҪ�㷨�������ַ���ת��Ϊ��������ַ���
	 * 
	 * @param message
	 * @return
	 */
	public static String getMD5(String message) {
		String encryptedString = null;

		try {
			MessageDigest mdigest = MessageDigest.getInstance("MD5");
			mdigest.update(message.getBytes());

			StringBuilder sb = new StringBuilder();
			for (byte b : mdigest.digest()) {
				sb.append(String.format("%02X", b));
			}
			encryptedString = sb.toString();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}

		return encryptedString;
	}

	/**
	 * ʹ��AES�����㷨����
	 * 
	 * @param message
	 * @return
	 */
	public static byte[] encryptAES(String content, String password) {
		try {
			KeyGenerator kgen = KeyGenerator.getInstance("AES");
			kgen.init(128, new SecureRandom(password.getBytes()));
			SecretKey secretKey = kgen.generateKey();
			byte[] enCodeFormat = secretKey.getEncoded();
			SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
			Cipher cipher = Cipher.getInstance("AES");
			byte[] byteContent = content.getBytes("utf-8");
			cipher.init(Cipher.ENCRYPT_MODE, key);
			byte[] result = cipher.doFinal(byteContent);
			return result;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * ����
	 * 
	 * @param content
	 *            ����������
	 * @param password
	 *            ������Կ
	 * @return
	 */
	public static byte[] decryptAES(byte[] content, String password) {
		try {
			KeyGenerator kgen = KeyGenerator.getInstance("AES");
			kgen.init(128, new SecureRandom(password.getBytes()));
			SecretKey secretKey = kgen.generateKey();
			byte[] enCodeFormat = secretKey.getEncoded();
			SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
			Cipher cipher = Cipher.getInstance("AES");
			cipher.init(Cipher.DECRYPT_MODE, key);
			byte[] result = cipher.doFinal(content);
			return result;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * ��������ת����16����
	 * 
	 * @param buf
	 * @return
	 */
	@SuppressLint("DefaultLocale")
	public static String parseByte2HexStr(byte buf[]) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < buf.length; i++) {
			String hex = Integer.toHexString(buf[i] & 0xFF);
			if (hex.length() == 1) {
				hex = '0' + hex;
			}
			sb.append(hex.toUpperCase());
		}
		return sb.toString();
	}

	/**
	 * ��16����ת��Ϊ������
	 * 
	 * @param hexStr
	 * @return
	 */
	public static byte[] parseHexStr2Byte(String hexStr) {
		if (hexStr.length() < 1)
			return null;
		byte[] result = new byte[hexStr.length() / 2];
		for (int i = 0; i < hexStr.length() / 2; i++) {
			int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
			int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2),
					16);
			result[i] = (byte) (high * 16 + low);
		}
		return result;
	}
}