DES3 加密算法

Des3加密算法是一种对称加密算法，本文仅仅简单调用jdk中的方法实现


DES3 加密算法类

import java.security.MessageDigest;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/**
 * Created by abner-l on 15/4/16.
 * Des3 加密算法
 */
public class DES3Encrypt {
    public static final String KEY_ALGORITHM = "DESede";
    public static final String MD5 = "MD5";
    // 算法名称/加密模式/填充方式
    public static final String CIPHER_ALGORITHM = "DESede/CBC/PKCS5Padding";
    public static final String DEFAULT_CHARSET = "UTF-8";

    public static String encrypt(String keyStr, String message) throws Exception {

        MessageDigest md5 = MessageDigest.getInstance(MD5);
        final byte[] keyBytes = md5.digest(keyStr.getBytes(DEFAULT_CHARSET));

        final SecretKey key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
        final IvParameterSpec iv = new IvParameterSpec(new byte[8]);
        final Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key, iv);

        final byte[] plainTextBytes = message.getBytes(DEFAULT_CHARSET);
        final byte[] cipherText = cipher.doFinal(plainTextBytes);

        return Base64.encode(cipherText);
    }

    public static String decrypt(String keyStr, String message) throws Exception {

        MessageDigest md5 = MessageDigest.getInstance(MD5);
        final byte[] keyBytes = md5.digest(keyStr.getBytes(DEFAULT_CHARSET));

        final SecretKey key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
        final IvParameterSpec iv = new IvParameterSpec(new byte[8]);
        final Cipher decipher = Cipher.getInstance(CIPHER_ALGORITHM);
        decipher.init(Cipher.DECRYPT_MODE, key, iv);

        final byte[] plainText = decipher.doFinal(Base64.decode(message));

        return new String(plainText, DEFAULT_CHARSET);
    }

}

Base64 加密类

import java.io.IOException;
import java.io.OutputStream;

/**
 * Base64编码工具类
 */
public class Base64 {
    private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();

    public static String encode(byte[] data) {
        int start = 0;
        int len = data.length;
        StringBuffer buf = new StringBuffer(data.length * 3 / 2);

        int end = len - 3;
        int i = start;
        int n = 0;

        while (i <= end) {
            int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 0x0ff) << 8) | (((int) data[i + 2]) & 0x0ff); 
            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append(legalChars[d & 63]);

            i += 3;

            if (n++ >= 14) {
                n = 0;
                buf.append(" ");
            }
        }

        if (i == start + len - 2) {
            int d = ((((int) data[i]) & 0x0ff) << 16) | ((((int) data[i + 1]) & 255) << 8);
            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append("=");
        } else if (i == start + len - 1) {
            int d = (((int) data[i]) & 0x0ff) << 16;
            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append("==");
        }

        return buf.toString();
    }

    private static int decode(char c) {
        if (c >= 'A' && c <= 'Z')
            return ((int) c) - 65; 
        else if (c >= 'a' && c <= 'z') 
            return ((int) c) - 97 + 26; 
        else if (c >= '0' && c <= '9')
            return ((int) c) - 48 + 26 + 26;
        else
            switch (c) {
                case '+':
                    return 62;
                case '/':
                    return 63;
                case '=':
                    return 0;
                default:
                    throw new RuntimeException("unexpected code: " + c);
            }
    }

    /**
     * Base64 解码
     */

    public static byte[] decode(String s) {

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            decode(s, bos);
        } catch (IOException e) {
            throw new RuntimeException();
        }
        byte[] decodedBytes = bos.toByteArray();
        try {
            bos.close();
            bos = null;
        } catch (IOException ex) {
            System.err.println("Error while decoding BASE64: " + ex.toString());
        }
        return decodedBytes;
    }

    private static void decode(String s, OutputStream os) throws IOException {
        int i = 0;

        int len = s.length();

        while (true) {
            while (i < len && s.charAt(i) <= ' ')
                i++;

            if (i == len)
                break;

            int tri = (decode(s.charAt(i)) << 18) + (decode(s.charAt(i + 1)) << 12) + (decode(s.charAt(i + 2)) << 6) + (decode(s.charAt(i + 3))); 
            os.write((tri >> 16) & 255);
            if (s.charAt(i + 2) == '=')
                break;
            os.write((tri >> 8) & 255);
            if (s.charAt(i + 3) == '=')
                break;
            os.write(tri & 255);

            i += 4;
        }
    }
}

注意：

1. 由于DES3加密使用的密钥长度只能是128位、或者是192位，也就是16字节或者24字节，所以对传入的key做一次MD5加密生成一个16字节的key；
2. 通过DES3加密后的数据是无法编码的转化为String（有谁能找到方法告诉我），所以通过Base64编码后，利于与服务器的数据传递。

原文地址