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。

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