MD5算法的Java实现

//使用MD5算法对密码加密之后，会得到一个唯一的并且是不可逆转的字符串编码 //将加密后所得到的字符串编码作为密码标识符存储在数据库中，可以防止密码在数据库中被盗窃 //并且加密后的字符串编码是不能再转换到原有密码，这就保证了存储在数据库中的密码的安全性 //所以在用户校验时，不能直接把登录密码和数据库中存储的密码标识符进行比较 //而是需要将用户的登录密码也进行MD5转换，然后才可以进行比较 //下面的代码就实现了MD5算法对字符串进行加密的功能 /** * 实现了MD5算法对字符串进行加密的功能 * @see 直接调用MD5类中的toMD5()方法 * @see 即可对需要加密的字符串进行加密 */ public class MD5 { //下面这些S11-S44实际上是一个4*4的矩阵，在原始的C实现中是用#define实现的 //这里把它们实现成为static final是表示只读，且能在同一个进程空间内的多个Instance间共享 static final int S11 = 7; static final int S12 = 12; static final int S13 = 17; static final int S14 = 22; static final int S21 = 5; static final int S22 = 9; static final int S23 = 14; static final int S24 = 20; static final int S31 = 4; static final int S32 = 11; static final int S33 = 16; static final int S34 = 23; static final int S41 = 6; static final int S42 = 10; static final int S43 = 15; static final int S44 = 21; static final byte[] PADDING = {-128, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; /** * 下面的3个成员是MD5计算过程中用到的3个核心数据，在原始的C实现中被定义到MD5_CTX结构中 */ private long[] state = new long[4]; //state() private long[] count = new long[2]; //number of bits, modulo 2^64 (Isb first) private byte[] buffer = new byte[64]; //input buffer //digestHexStr是MD5.java的唯一一个公共成员，是最新一次计算结果的十六进制ASCII表示 //即此变量中存放了将输入串进行MD5运算后的128位MD5码的ASCII码� public String digestHexStr; //digest是最新一次计算结果的二进制内部表示，表示128bit的MD5值 private byte[] digest = new byte[16]; /** * 这是类MD5最主要的公共方法 * @param inbuf 入口参数是你想要进行MD5变换的字符串 * @return 返回变换完的结果，该结果是从公共成员digestHexStr取得的 */ public String getMD5ofStr(String inbuf){ md5Init(); md5Update(inbuf.getBytes(), inbuf.length()); md5Final(); digestHexStr = ""; for(int i=0; i<16; i++){ digestHexStr += byteHEX(digest[i]); } return digestHexStr; } /** * 这是MD5类的标准构造函数，JavaBean要求有一个public的并且没有参数的构造函数 */ public MD5(){ md5Init(); return; } /** * 这是一个初始化函数，初始化核心变量，装入标准的函数 */ private void md5Init(){ count[0] = 0L; count[1] = 0L; //Load magic initialization constants state[0] = 0x67452301L; state[1] = 0xefcdab89L; state[2] = 0x98badcfeL; state[3] = 0x10325476L; } //F, G, H, I是4个基本的MD5函数 //在原始的MD5的C实现中，由于它们是简单的位运算，可能出于效率的考虑把它们实现成了宏 //在Java中，我们把它们实现成了private方法，名字保持了原来C中的 private long F(long x, long y, long z){ return (x&y) | ((~x)&z); } private long G(long x, long y, long z){ return (x&z) | (y&(~z)); } private long H(long x, long y, long z){ return x ^ y ^ z; } private long I(long x, long y, long z){ return y ^ (x | (~z)); } //FF, GG, HH和II将调用F, G, H, I进行进一步变换 //FF, GG, HH and II transformations for rounds 1,2,3 and 4 //Rotation is separate from addition to prevent recomputation private long FF(long a, long b, long c, long d, long x, long s, long ac){ a += F(b, c, d) + x + ac; a = ((int)a << s) | ((int)a >>> (32-s)); a += b; return a; } private long GG(long a, long b, long c, long d, long x, long s, long ac){ a += G(b, c, d) + x + ac; a = ((int)a << s) | ((int)a >>> (32-s)); a += b; return a; } private long HH(long a, long b, long c, long d, long x, long s, long ac){ a += H(b, c, d) + x + ac; a = ((int)a << s) | ((int)a >>> (32-s)); a += b; return a; } private long II(long a, long b, long c, long d, long x, long s, long ac){ a += I(b, c, d) + x + ac; a = ((int)a << s) | ((int)a >>> (32-s)); a += b; return a; } /** * 这是MD5的主计算过程。该函数由getMD5ofStr调用 * @see 该函数在被调用之前需要调用md5Init，因此把它设计成private的 * @param inbuf 要进行MD5加密的字节串 * @param inputLen 字符串长度 */ private void md5Update(byte[] inbuf, int inputLen){ int i, index, partLen; byte[] block = new byte[64]; index = (int)(count[0]>>>3) & 0x3F; //Update number of bits if((count[0] += (inputLen<<3)) < (inputLen << 3)) count[1]++; count[1] += (inputLen >>> 29); partLen = 64 - index; //Transform as many times as possible if(inputLen >= partLen){ md5Memcpy(buffer, inbuf, index, 0, partLen); md5Transform(buffer); for(i=partLen; i+63<inputLen; i+=64){ md5Memcpy(block, inbuf, 0, i, 64); md5Transform(block); } index = 0; }else i = 0; //Buffer remaining input md5Memcpy(buffer, inbuf, index, i, inputLen-i); } /** * 整理和填写输出结果 * @see 将得到的128位(16字节)的MD5码存放在digest数组 */ private void md5Final(){ byte[] bits = new byte[8]; int index, padLen; //Save number of bits Encode(bits, count, 8); //Pad out to 56 mod 64 index = (int)(count[0]>>>3) & 0x3f; padLen = (index<56) ? (56-index) : (120-index); md5Update(PADDING, padLen); //Append length (before padding) md5Update(bits, 8); //Store state in digest Encode(digest, state, 16); } /** * 这是一个内部使用的byte数组的块复制函数 * @see 从input的inpos开始把len长度的字节复制到output的outpos位置开始 */ private void md5Memcpy(byte[] output, byte[] input, int outpos, int inpos, int len){ int i; for(i=0; i<len; i++) output[outpos+i] = input[inpos+i]; } /** * 这是MD5核心变换程序。由md5Update调用 * @param block 分块的原始字节 */ private void md5Transform(byte block[]){ long a=state[0], b=state[1], c=state[2], d=state[3]; long[] x = new long[16]; Decode(x, block, 64); /*Round 1*/ a = FF(a, b, c, d, x[0], S11, 0xd76aa478L); // 1 d = FF(d, a, b, c, x[1], S12, 0xe8c7b756L); // 2 c = FF(c, d, a, b, x[2], S13, 0x242070dbL); // 3 b = FF(b, c, d, a, x[3], S14, 0xc1bdceeeL); // 4 a = FF(a, b, c, d, x[4], S11, 0xf57c0fafL); // 5 d = FF(d, a, b, c, x[5], S12, 0x4787c62aL); // 6 c = FF(c, d, a, b, x[6], S13, 0xa8304613L); // 7 b = FF(b, c, d, a, x[7], S14, 0xfd469501L); // 8 a = FF(a, b, c, d, x[8], S11, 0x698098d8L); // 9 d = FF(d, a, b, c, x[9], S12, 0x8b44f7afL); //10 c = FF(c, d, a, b, x[10], S13, 0xffff5bb1L); //11 b = FF(b, c, d, a, x[11], S14, 0x895cd7beL); //12 a = FF(a, b, c, d, x[12], S11, 0x6b901122L); //13 d = FF(d, a, b, c, x[13], S12, 0xfd987193L); //14 c = FF(c, d, a, b, x[14], S13, 0xa679438eL); //15 b = FF(b, c, d, a, x[15], S14, 0x49b40821L); //16 /*Round 2*/ a = GG(a, b, c, d, x[1], S21, 0xf61e2562L); //17 d = GG(d, a, b, c, x[6], S22, 0xc040b340L); //18 c = GG(c, d, a, b, x[11], S23, 0x265e5a51L); //19 b = GG(b, c, d, a, x[0], S24, 0xe9b6c7aaL); //20 a = GG(a, b, c, d, x[5], S21, 0xd62f105dL); //21 d = GG(d, a, b, c, x[10], S22, 0x2441453L); //22 c = GG(c, d, a, b, x[15], S23, 0xd8a1e681L); //23 b = GG(b, c, d, a, x[4], S24, 0xe7d3fbc8L); //24 a = GG(a, b, c, d, x[9], S21, 0x21e1cde6L); //25 d = GG(d, a, b, c, x[14], S22, 0xc33707d6L); //26 c = GG(c, d, a, b, x[3], S23, 0xf4d50d87L); //27 b = GG(b, c, d, a, x[8], S24, 0x455a14edL); //28 a = GG(a, b, c, d, x[13], S21, 0xa9e3e905L); //29 d = GG(d, a, b, c, x[2], S22, 0xfcefa3f8L); //30 c = GG(c, d, a, b, x[7], S23, 0x676f02d9L); //31 b = GG(b, c, d, a, x[12], S24, 0x8d2a4c8aL); //32 /*Round 3*/ a = HH(a, b, c, d, x[5], S31, 0xfffa3942L); //33 d = HH(d, a, b, c, x[8], S32, 0x8771f681L); //34 c = HH(c, d, a, b, x[11], S33, 0x6d9d6122L); //35 b = HH(b, c, d, a, x[14], S34, 0xfde5380cL); //36 a = HH(a, b, c, d, x[1], S31, 0xa4beea44L); //37 d = HH(d, a, b, c, x[4], S32, 0x4bdecfa9L); //38 c = HH(c, d, a, b, x[7], S33, 0xf6bb4b60L); //39 b = HH(b, c, d, a, x[10], S34, 0xbebfbc70L); //40 a = HH(a, b, c, d, x[13], S31, 0x289b7ec6L); //41 d = HH(d, a, b, c, x[0], S32, 0xeaa127faL); //42 c = HH(c, d, a, b, x[3], S33, 0xd4ef3085L); //43 b = HH(b, c, d, a, x[6], S34, 0x4881d05L); //44 a = HH(a, b, c, d, x[9], S31, 0xd9d4d039L); //45 d = HH(d, a, b, c, x[12], S32, 0xe6db99e5L); //46 c = HH(c, d, a, b, x[15], S33, 0x1fa27cf8L); //47 b = HH(b, c, d, a, x[2], S34, 0xc4ac5665L); //48 /*Round 4*/ a = II(a, b, c, d, x[0], S41, 0xf4292244L); //49 d = II(d, a, b, c, x[7], S42, 0x432aff97L); //50 c = II(c, d, a, b, x[14], S43, 0xab9423a7L); //51 b = II(b, c, d, a, x[5], S44, 0xfc93a039L); //52 a = II(a, b, c, d, x[12], S41, 0x655b59c3L); //53 d = II(d, a, b, c, x[3], S42, 0x8f0ccc92L); //54 c = II(c, d, a, b, x[10], S43, 0xfeff47dL); //55 b = II(b, c, d, a, x[1], S44, 0x85845dd1L); //56 a = II(a, b, c, d, x[8], S41, 0x6fa87e4fL); //57 d = II(d, a, b, c, x[15], S42, 0xfe2ce6e0L); //58 c = II(c, d, a, b, x[6], S43, 0xa3014314L); //59 b = II(b, c, d, a, x[13], S44, 0x4e0811a1L); //60 a = II(a, b, c, d, x[4], S41, 0xf7537e82L); //61 d = II(d, a, b, c, x[11], S42, 0xbd3af235L); //62 c = II(c, d, a, b, x[2], S43, 0x2ad7d2bbL); //63 b = II(b, c, d, a, x[9], S44, 0xeb86d391L); //64 state[0] += a; state[1] += b; state[2] += c; state[3] += d; } /** * 把long数组按顺序拆成byte数组 * @see 因为Java的long类型是64bit的，只拆低32bit，以适应原始C实现的用途 */ private void Encode(byte[] output, long[] input, int len){ int i, j; for(i=0,j=0; j<len; i++,j+=4){ output[j] = (byte)(input[i] & 0xffL); output[j+1] = (byte)((input[i]>>>8) & 0xffL); output[j+2] = (byte)((input[i]>>>16) & 0xffL); output[j+3] = (byte)((input[i]>>>24) & 0xffL); } } /** * 把byte数组按顺序合成long数组 * @see 因为Java的long类型是64bit的，只合成低32bit，高32bit清零，以适应原始C实现的用途 */ private void Decode(long[] output, byte[] input, int len){ int i, j; for(i=0,j=0; j<len; i++,j+=4) output[i] = b2iu(input[j]) | (b2iu(input[j+1])<<8) | (b2iu(input[j+2])<<16) | (b2iu(input[j+3])<<24); return; } /** * 将一字节的有符号数转换成一无符号的long型值 * @see 该方法是一个把byte按照不考虑正负号的原则的"升位"程序 * @see 因为Java没有unsigned运算 */ public static long b2iu(byte b){ //或者写成return b >= 0 ? b : b & 0xff; return b<0 ? b&0x7F+128 : b; } /** * 该方法用来把一个byte类型的数转换成十六进制的ASCII表示 * @see 因为Java中的byte的toString无法实现这一点 * @see 而我们又没有C语言中的sprintf(outbuf, "%02X", ib) */ public static String byteHEX(byte ib){ char[] Digit = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'}; char[] ob = new char[2]; ob[0] = Digit[(ib>>>4) & 0X0F]; ob[1] = Digit[ib & 0X0F]; String s = new String(ob); return s; } /** * 对需要加密的字符串进行加密 * @see 即对字符串source进行MD5运算，返回该串的MD5字符串 */ public static String toMD5(String source){ MD5 md5 = new MD5(); return md5.getMD5ofStr(source); } public static void main(String[] args) { System.out.println(toMD5("My name is Jadyer")); } }