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MD5Code:
 package com.util;
public class MD5Code
   {
  /**//*
 * 下面這些S11-S44實際上是一個4*4的矩陣，在原始的C實現中是用#define 實現的， 這里把它們實現成為static
* final是表示了只讀，切能在同一個進程空間內的多個 Instance間共享
 */
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 MD5Code()
{
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 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;
}
/**//*
* 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);
}
/**//*
* md5Final整理和填寫輸出結果
*/
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是我寫的一個把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;
}
 }
測試類:
package com.test;
import com.util.MD5Code;
public class MD5CodeTest
{
public static void main(String[] args)
{
String name = "zdw";
MD5Code code = new MD5Code();
System.out.println(code.getMD5ofStr(name).length());
System.out.println(code.getMD5ofStr(name).equals(code.getMD5ofStr("zdw")));
}
}
這樣就保證了在數據庫里需要加密的字段的安全性.
如果需要比較,用輸入的字符串MD5加密后和數據庫的相比,
就能判斷是否相等.
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