下面是一个利用JAVA写的MD5加密程序,哪位高手帮我看看这几句是什么意思啊,好像是通过MD5的C源程序直接改过来的:
private void md5Update(byte[] inbuf, int inputLen) { int i, index, partLen;
byte[] block = new byte[64];
index = (int)(count[0] >;>;>; 3) & 0x3F; >;>;>; 表示无符号右移,但为什么要和0x3F进行与运算啊
// /* Update number of bits */
if ((count[0] += (inputLen << 3)) < (inputLen << 3)) 后面的这几句也不明白啊,还请高手帮忙看看
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); }源代码如下:部分已经删除
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是表示了只读,切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 };
/* 下面的三个成员是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 (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的唯一一个公共成员,是最新一次计算结果的
16进制ASCII表示.
*/
public String digestHexStr;
/* digest,是最新一次计算结果的2进制内部表示,表示128bit的MD5值.
*/
private byte[] digest = new byte[16];
/*
getMD5ofStr是类MD5最主要的公共方法,入口参数是你想要进行MD5变换的字符串
返回的是变换完的结果,这个结果是从公共成员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这个类的标准构造函数,JavaBean要求有一个public的并且没有参数的构造函数
public MD5() {
md5Init(); return;
}
/* md5Init是一个初始化函数,初始化核心变量,装入标准的幻数 */
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; return;
}
/*
md5Update是MD5的主计算过程,inbuf是要变换的字节串,inputlen是长度,这个
函数由getMD5ofStr调用,调用之前需要调用md5init,因此把它设计成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整理和填写输出结果
*/
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是一个内部使用的byte数组的块拷贝函数,从input的inpos开始把len长度的
字节拷贝到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];
}
public static void main(String args[]) {
MD5 m = new MD5();
if (Array.getLength(args) == 0) { //如果没有参数,执行标准的Test Suite
System.out.println("MD5 Test suite:");
System.out.println("MD5(\"\"):"+m.getMD5ofStr(""));
System.out.println("MD5(\"a\"):"+m.getMD5ofStr("a"));
System.out.println("MD5(\"abc\"):"+m.getMD5ofStr("abc"));
System.out.println("MD5(\"message digest\"):"+m.getMD5ofStr("message digest"));
System.out.println("MD5(\"abcdefghijklmnopqrstuvwxyz\"):"+
m.getMD5ofStr("abcdefghijklmnopqrstuvwxyz"));
System.out.println("MD5(\"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789\"):"+
m.getMD5ofStr("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"));
}
else
System.out.println("MD5(" + args[0] + ")=" + m.getMD5ofStr(args[0]));
}}
private void md5Update(byte[] inbuf, int inputLen) { int i, index, partLen;
byte[] block = new byte[64];
index = (int)(count[0] >;>;>; 3) & 0x3F; >;>;>; 表示无符号右移,但为什么要和0x3F进行与运算啊
// /* Update number of bits */
if ((count[0] += (inputLen << 3)) < (inputLen << 3)) 后面的这几句也不明白啊,还请高手帮忙看看
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); }源代码如下:部分已经删除
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是表示了只读,切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 };
/* 下面的三个成员是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 (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的唯一一个公共成员,是最新一次计算结果的
16进制ASCII表示.
*/
public String digestHexStr;
/* digest,是最新一次计算结果的2进制内部表示,表示128bit的MD5值.
*/
private byte[] digest = new byte[16];
/*
getMD5ofStr是类MD5最主要的公共方法,入口参数是你想要进行MD5变换的字符串
返回的是变换完的结果,这个结果是从公共成员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这个类的标准构造函数,JavaBean要求有一个public的并且没有参数的构造函数
public MD5() {
md5Init(); return;
}
/* md5Init是一个初始化函数,初始化核心变量,装入标准的幻数 */
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; return;
}
/*
md5Update是MD5的主计算过程,inbuf是要变换的字节串,inputlen是长度,这个
函数由getMD5ofStr调用,调用之前需要调用md5init,因此把它设计成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整理和填写输出结果
*/
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是一个内部使用的byte数组的块拷贝函数,从input的inpos开始把len长度的
字节拷贝到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];
}
public static void main(String args[]) {
MD5 m = new MD5();
if (Array.getLength(args) == 0) { //如果没有参数,执行标准的Test Suite
System.out.println("MD5 Test suite:");
System.out.println("MD5(\"\"):"+m.getMD5ofStr(""));
System.out.println("MD5(\"a\"):"+m.getMD5ofStr("a"));
System.out.println("MD5(\"abc\"):"+m.getMD5ofStr("abc"));
System.out.println("MD5(\"message digest\"):"+m.getMD5ofStr("message digest"));
System.out.println("MD5(\"abcdefghijklmnopqrstuvwxyz\"):"+
m.getMD5ofStr("abcdefghijklmnopqrstuvwxyz"));
System.out.println("MD5(\"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789\"):"+
m.getMD5ofStr("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"));
}
else
System.out.println("MD5(" + args[0] + ")=" + m.getMD5ofStr(args[0]));
}}
count[0] >>>3获得的是要变换的数据所占用的字节数;
0x3F的二进制码为000...00111111;
经过&操作,获得的是占用的字节数的最后六位的值,最后六位刚好是64字节,
也就是说要获得最后不够64字节那部分的内容的长度!最后,还是多学学位运算,多充充电吧,呵呵!