隨筆檔案(496)

import java.lang.reflect.*;

/*************************************************
md5 類實現了RSA Data Security, Inc.在提交給IETF
的RFC1321中的MD5 message-digest 算法。
*************************************************/

public class MD5
{
// 下面這些S11-S44實際上是一個4*4的矩陣，這樣寫是方便修改
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 };

// 下面的三個成員是MD5計算過程中用到的3個核心數據，在原始的C實現中
// 被定義到MD5_CTX結構中

private long[] state = new long[4];??? // state (ABCD)
private long[] count = new long[2];??? // number of bits, modulo 2^64 (lsb first)
private byte[] buffer = new byte[64]; // input buffer

// digestHexStr是MD5的唯一一個公共成員，是最新一次計算結果的
//??? 16進制ASCII表示.

public String digestHexStr;

// digest,是最新一次計算結果的2進制內部表示，表示128bit的MD5值.

private byte[] digest = new byte[16];

// getMD5ofStr是類MD5最主要的公共方法，入口參數是你想要進行MD5變換的字符串
//??? 返回的是變換完的結果，這個結果是從公共成員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;
}

// 這是MD5這個類的標準構造函數，JavaBean要求有一個public的并且沒有參數的構造函數
public MD5()
{
??? md5Init();
??? return;
}

// md5Init是一個初始化函數，初始化核心變量，裝入標準的幻數

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;

??? return;
}

// F, G, H ,I 是4個基本的MD5函數，在原始的MD5的C實現中，由于它們是
//??? 簡單的位運算，可能出于效率的考慮把它們實現成了宏，在java中，我們把它們
// 實現成了private方法，名字保持了原來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將調用F,G,H,I進行近一步變換

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;
}

// md5Update是MD5的主計算過程，inbuf是要變換的字節串，inputlen是長度，這個
// 函數由getMD5ofStr調用，調用之前需要調用md5init，因此把它設計成private的
??
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);
}
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);
}

// md5Memcpy是一個內部使用的byte數組的塊拷貝函數，從input的inpos開始把len長度的
??? //??? 字節拷貝到output的outpos位置開始
??
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];
}

// md5Transform是MD5核心變換程序，有md5Update調用，block是分塊的原始字節
??
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, 0xffeff47dL); /* 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;
}

// Encode把long數組按順序拆成byte數組，因為java的long類型是64bit的，
// 只拆低32bit，以適應原始C實現的用途
??
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);
??? }
}

// Decode把byte數組按順序合成成long數組，因為java的long類型是64bit的，
??? //??? 只合成低32bit，高32bit清零，以適應原始C實現的用途
??
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;
}

// b2iu是一個把byte按照不考慮正負號的原則的＂升位＂程序，因為java沒有unsigned運算
??
public static long b2iu(byte b) {
??? return b < 0 ? b & 0x7F + 128 : b;
}

// byteHEX()，用來把一個byte類型的數轉換成十六進制的ASCII表示，
//???? 因為java中的byte的toString無法實現這一點，我們又沒有C語言中的
//???? 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;
}

public static String toMD5(String source)
{
??? MD5 md5 = new MD5();
??? return md5.getMD5ofStr(source);
}

public static void main(String[] args)
{
MD5 md5 = new MD5();
System.out.println(md5.toMD5(args[0]));
}
}

先編譯javac MD5.java,后帶字符串參數運行,如:java MD5 abc

//結果生成 32位的加密字符串，有的實例中截取的是加密字串的 8--24位，長度為16位．