在我们开发中经常会涉及到加密之类的功能，目前最常见的就是MD5 加密，我这里有几个加密的例子以供参考：
package com.yuri.util;
public class MD5
{
public MD5(Object ob)
{
this();
Update(ob.toString());
}
public MD5()
{
Init();
}
private int[] Decode(byte buffer[], int len, int shift)
{
int out[] = new int[16];
int j;
int i = j = 0;
for(; j < len; j += 4)
{
out[i] = buffer[j + shift] & 0xff | (buffer[j + 1 + shift] & 0xff) << 8 | (buffer[j + 2 + shift] & 0xff) << 16 | (buffer[j + 3 + shift] & 0xff) << 24;
i++;
}
return out;
}
private byte[] Encode(int input[], int len)
{
byte out[] = new byte[len];
int j;
int i = j = 0;
for(; j < len; j += 4)
{
out[j] = (byte)(input[i] & 0xff);
out[j + 1] = (byte)(input[i] >>> 8 & 0xff);
out[j + 2] = (byte)(input[i] >>> 16 & 0xff);
out[j + 3] = (byte)(input[i] >>> 24 & 0xff);
i++;
}
return out;
}
private int FF(int a, int b, int c, int d, int x, int s, int ac)
{
a = uadd(a, b & c | ~b & d, x, ac);
return uadd(rotate_left(a, s), b);
}
public synchronized byte[] Final()
{
if(finals == null)
{
MD5State fin = new MD5State(state);
byte bits[] = Encode(fin.count, 8);
int index = fin.count[0] >>> 3 & 0x3f;
int padlen = index >= 56 ? 120 - index : 56 - index;
Update(fin, padding, 0, padlen);
Update(fin, bits, 0, 8);
finals = fin;
}
return Encode(finals.state, 16);
}
private int GG(int a, int b, int c, int d, int x, int s, int ac)
{
a = uadd(a, b & d | c & ~d, x, ac);
return uadd(rotate_left(a, s), b);
}
private int HH(int a, int b, int c, int d, int x, int s, int ac)
{
a = uadd(a, b ^ c ^ d, x, ac);
return uadd(rotate_left(a, s), b);
}
private int II(int a, int b, int c, int d, int x, int s, int ac)
{
a = uadd(a, c ^ (b | ~d), x, ac);
return uadd(rotate_left(a, s), b);
}
public synchronized void Init()
{
state = new MD5State();
finals = null;
}
private void Transform(MD5State state, byte buffer[], int shift)
{
int a = state.state[0];
int b = state.state[1];
int c = state.state[2];
int d = state.state[3];
int x[] = Decode(buffer, 64, shift);
a = FF(a, b, c, d, x[0], 7, 0xd76aa478);
d = FF(d, a, b, c, x[1], 12, 0xe8c7b756);
c = FF(c, d, a, b, x[2], 17, 0x242070db);
b = FF(b, c, d, a, x[3], 22, 0xc1bdceee);
a = FF(a, b, c, d, x[4], 7, 0xf57c0faf);
d = FF(d, a, b, c, x[5], 12, 0x4787c62a);
c = FF(c, d, a, b, x[6], 17, 0xa8304613);
b = FF(b, c, d, a, x[7], 22, 0xfd469501);
a = FF(a, b, c, d, x[8], 7, 0x698098d8);
d = FF(d, a, b, c, x[9], 12, 0x8b44f7af);
c = FF(c, d, a, b, x[10], 17, -42063);
b = FF(b, c, d, a, x[11], 22, 0x895cd7be);
a = FF(a, b, c, d, x[12], 7, 0x6b901122);
d = FF(d, a, b, c, x[13], 12, 0xfd987193);
c = FF(c, d, a, b, x[14], 17, 0xa679438e);
b = FF(b, c, d, a, x[15], 22, 0x49b40821);
a = GG(a, b, c, d, x[1], 5, 0xf61e2562);
d = GG(d, a, b, c, x[6], 9, 0xc040b340);
c = GG(c, d, a, b, x[11], 14, 0x265e5a51);
b = GG(b, c, d, a, x[0], 20, 0xe9b6c7aa);
a = GG(a, b, c, d, x[5], 5, 0xd62f105d);
d = GG(d, a, b, c, x[10], 9, 0x2441453);
c = GG(c, d, a, b, x[15], 14, 0xd8a1e681);
b = GG(b, c, d, a, x[4], 20, 0xe7d3fbc8);
a = GG(a, b, c, d, x[9], 5, 0x21e1cde6);
d = GG(d, a, b, c, x[14], 9, 0xc33707d6);
c = GG(c, d, a, b, x[3], 14, 0xf4d50d87);
b = GG(b, c, d, a, x[8], 20, 0x455a14ed);
a = GG(a, b, c, d, x[13], 5, 0xa9e3e905);
d = GG(d, a, b, c, x[2], 9, 0xfcefa3f8);
c = GG(c, d, a, b, x[7], 14, 0x676f02d9);
b = GG(b, c, d, a, x[12], 20, 0x8d2a4c8a);
a = HH(a, b, c, d, x[5], 4, 0xfffa3942);
d = HH(d, a, b, c, x[8], 11, 0x8771f681);
c = HH(c, d, a, b, x[11], 16, 0x6d9d6122);
b = HH(b, c, d, a, x[14], 23, 0xfde5380c);
a = HH(a, b, c, d, x[1], 4, 0xa4beea44);
d = HH(d, a, b, c, x[4], 11, 0x4bdecfa9);
c = HH(c, d, a, b, x[7], 16, 0xf6bb4b60);
b = HH(b, c, d, a, x[10], 23, 0xbebfbc70);
a = HH(a, b, c, d, x[13], 4, 0x289b7ec6);
d = HH(d, a, b, c, x[0], 11, 0xeaa127fa);
c = HH(c, d, a, b, x[3], 16, 0xd4ef3085);
b = HH(b, c, d, a, x[6], 23, 0x4881d05);
a = HH(a, b, c, d, x[9], 4, 0xd9d4d039);
d = HH(d, a, b, c, x[12], 11, 0xe6db99e5);
c = HH(c, d, a, b, x[15], 16, 0x1fa27cf8);
b = HH(b, c, d, a, x[2], 23, 0xc4ac5665);
a = II(a, b, c, d, x[0], 6, 0xf4292244);
d = II(d, a, b, c, x[7], 10, 0x432aff97);
c = II(c, d, a, b, x[14], 15, 0xab9423a7);
b = II(b, c, d, a, x[5], 21, 0xfc93a039);
a = II(a, b, c, d, x[12], 6, 0x655b59c3);
d = II(d, a, b, c, x[3], 10, 0x8f0ccc92);
c = II(c, d, a, b, x[10], 15, 0xffeff47d);
b = II(b, c, d, a, x[1], 21, 0x85845dd1);
a = II(a, b, c, d, x[8], 6, 0x6fa87e4f);
d = II(d, a, b, c, x[15], 10, 0xfe2ce6e0);
c = II(c, d, a, b, x[6], 15, 0xa3014314);
b = II(b, c, d, a, x[13], 21, 0x4e0811a1);
a = II(a, b, c, d, x[4], 6, 0xf7537e82);
d = II(d, a, b, c, x[11], 10, 0xbd3af235);
c = II(c, d, a, b, x[2], 15, 0x2ad7d2bb);
b = II(b, c, d, a, x[9], 21, 0xeb86d391);
state.state[0] += a;
state.state[1] += b;
state.state[2] += c;
state.state[3] += d;
}
public void Update(String s)
{
byte chars[] = s.getBytes();
Update(chars, chars.length);
}
public void Update(byte b)
{
byte buffer[] = new byte[1];
buffer[0] = b;
Update(buffer, 1);
}
public void Update(byte buffer[])
{
Update(buffer, 0, buffer.length);
}
public void Update(byte buffer[], int length)
{
Update(state, buffer, 0, length);
}
public void Update(byte buffer[], int offset, int length)
{
Update(state, buffer, offset, length);
}
public void Update(MD5State stat, byte buffer[], int offset, int length)
{
finals = null;
if(length - offset > buffer.length)
length = buffer.length - offset;
int index = stat.count[0] >>> 3 & 0x3f;
if((stat.count[0] += length << 3) < length << 3)
stat.count[1]++;
stat.count[1] += length >>> 29;
int partlen = 64 - index;
int i;
if(length >= partlen)
{
for(i = 0; i < partlen; i++)
stat.buffer[i + index] = buffer[i + offset];
Transform(stat, stat.buffer, 0);
for(i = partlen; i + 63 < length; i += 64)
Transform(stat, buffer, i);
index = 0;
} else
{
i = 0;
}
if(i < length)
{
int start = i;
for(; i < length; i++)
stat.buffer[(index + i) - start] = buffer[i + offset];
}
}
public String asHex()
{
return asHex(Final());
}
public static String asHex(byte hash[])
{
StringBuffer buf = new StringBuffer(hash.length * 2);
for(int i = 0; i < hash.length; i++)
{
if((hash[i] & 0xff) < 16)
buf.append("0");
buf.append(Long.toString(hash[i] & 0xff, 16));
}
return buf.toString();
}
public String debugDump()
{
return asHex();
}
public static String md5crypt(String input)
{
MD5 md5 = new MD5();
md5.Init();
md5.Update(input);
return md5.asHex();
}
private int rotate_left(int x, int n)
{
return x << n | x >>> 32 - n;
}
private int uadd(int a, int b, int c, int d)
{
return uadd(uadd(a, b, c), d);
}
private int uadd(int a, int b, int c)
{
return uadd(uadd(a, b), c);
}
private int uadd(int a, int b)
{
long aa = (long)a & 0xffffffffL;
long bb = (long)b & 0xffffffffL;
aa += bb;
return (int)(aa & 0xffffffffL);
}
MD5State finals;
static 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
};
MD5State state;
public static void main(String[] args)
{
System.out.println(MD5.md5crypt("1988"));
}
}package com.yuri.util;
class MD5State
{
public MD5State(MD5State from)
{
this();
for(int i = 0; i < buffer.length; i++)
buffer[i] = from.buffer[i];
for(int i = 0; i < state.length; i++)
state[i] = from.state[i];
for(int i = 0; i < count.length; i++)
count[i] = from.count[i];
}
public MD5State()
{
buffer = new byte[64];
count = new int[2];
state = new int[4];
state[0] = 0x67452301;
state[1] = 0xefcdab89;
state[2] = 0x98badcfe;
state[3] = 0x10325476;
count[0] = count[1] = 0;
}
byte buffer[];
int count[];
int state[];
}