我将一个txt文件放入两个不同的文件夹中，但名称相同。例如，我将file.txt放入两个目录中，并将它们命名为＆＃34; MY＆＃34;。我想计算他们的MD5值，所以我使用相同的算法用7z软件压缩这两个文件夹。然后是令人震惊的事情：两个.zip文件的MD5值不同。这个诀窍是什么？
java中的代码是：
String parseMd5Hex(FileInputStream fin ) throws IOException {
Md5 md5 = new Md5 (fin);
byte b[]= md5.getDigest();
return md5.parseToValue(b);
}
public class Md5 {
private static final int BUFFER_SIZE = 1024 ;
private static final int S11 = 7 ;
private static final int S12 = 12 ;
private static final int S13 = 17 ;
private static final int S14 = 22 ;
private static final int S21 = 5 ;
private static final int S22 = 9 ;
private static final int S23 = 14 ;
private static final int S24 = 20 ;
private static final int S31 = 4 ;
private static final int S32 = 11 ;
private static final int S33 = 16 ;
private static final int S34 = 23 ;
private static final int S41 = 6 ;
private static final int S42 = 10 ;
private static final int S43 = 15 ;
private static final int S44 = 21 ;
private static byte padding[] = {
(byte) 0x80, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0, (byte) 0,
(byte) 0, (byte) 0, (byte) 0, (byte) 0
} ;
private InputStream in = null ;
private boolean stringp = false ;
private int state[] = null ;
private long count = 0 ;
private byte buffer[] = null ;
private byte digest[] = null ;
private static String stringify (byte buf[]) {
StringBuffer sb = new StringBuffer(2*buf.length) ;
for (int i = 0 ; i < buf.length; i++) {
int h = (buf[i] & 0xf0) >> 4 ;
int l = (buf[i] & 0x0f) ;
sb.append (Character.valueOf((char)((h>9) ? 'a'+h-10 : '0'+h))) ;
sb.append (Character.valueOf((char)((l>9) ? 'a'+l-10 : '0'+l))) ;
}
return sb.toString() ;
}
private final int F(int x, int y, int z) {
return ((x & y) | ((~x) & z)) ;
}
private final int G(int x, int y, int z) {
return ((x & z) | (y & (~z))) ;
}
private final int H(int x, int y, int z) {
return (x ^ y ^ z) ;
}
private final int I(int x, int y, int z) {
return (y ^ (x | (~z))) ;
}
private final int rotate_left(int x, int n) {
return ((x << n) | (x >>> (32-n))) ;
}
private final int FF(int a,int b,int c,int d,int x,int s,int ac) {
a += (F(b, c, d) + x + ac) ;
a = rotate_left(a, s) ;
a += b ;
return a ;
}
private final int GG(int a,int b,int c,int d,int x,int s,int ac) {
a += (G(b, c, d) + x + ac) ;
a = rotate_left(a, s) ;
a += b ;
return a ;
}
private final int HH(int a,int b,int c,int d,int x,int s,int ac) {
a += (H(b, c, d) + x + ac) ;
a = rotate_left(a, s) ;
a += b ;
return a ;
}
private final int II(int a,int b,int c,int d,int x,int s,int ac) {
a += (I(b, c, d) + x + ac) ;
a = rotate_left(a, s) ;
a += b ;
return a;
}
private final void decode (int output[], byte input[], int off, int len) {
int i = 0 ;
int j = 0 ;
for ( ; j < len; i++, j += 4) {
output[i] = (((int) (input[off+j]&0xff))
| (((int) (input[off+j+1] & 0xff)) << 8)
| (((int) (input[off+j+2] & 0xff)) << 16)
| (((int) (input[off+j+3] & 0xff)) << 24)) ;
}
}
private final void transform (byte block[], int offset) {
int a = state[0] ;
int b = state[1] ;
int c = state[2] ;
int d = state[3] ;
int x[] = new int[16] ;
decode (x, block, offset, 64);
/* Round 1 */
a = FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
d = FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
c = FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
b = FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
a = FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
d = FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
c = FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
b = FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
a = FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
d = FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
c = FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
b = FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
a = FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
d = FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
c = FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
b = FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
/* Round 2 */
a = GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
d = GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
c = GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
b = GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
a = GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
d = GG (d, a, b, c, x[10], S22, 0x2441453); /* 22 */
c = GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
b = GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
a = GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
d = GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
c = GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
b = GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
a = GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
d = GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
c = GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
b = GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
/* Round 3 */
a = HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
d = HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
c = HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
b = HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
a = HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
d = HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
c = HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
b = HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
a = HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
d = HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
c = HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
b = HH (b, c, d, a, x[ 6], S34, 0x4881d05); /* 44 */
a = HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
d = HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
c = HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
b = HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */
/* Round 4 */
a = II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
d = II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
c = II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
b = II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
a = II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
d = II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
c = II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
b = II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
a = II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
d = II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
c = II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
b = II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
a = II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
d = II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
c = II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
b = II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
}
private final void update (byte input[], int len) {
int index = ((int) (count >> 3)) & 0x3f ;
count += (len << 3) ;
int partLen = 64 - index ;
int i = 0 ;
if ( len >= partLen ) {
System.arraycopy (input, 0, buffer, index, partLen) ;
transform (buffer, 0) ;
for (i = partLen ; i + 63 < len ; i+= 64)
transform (input, i) ;
index = 0 ;
} else {
i = 0 ;
}
System.arraycopy (input, i, buffer, index, len - i) ;
}
private byte[] end () {
byte bits[] = new byte[8] ;
for (int i = 0 ; i < 8 ; i++)
bits[i] = (byte) ((count>>>(i*8)) & 0xff) ;
int index = ((int) (count >> 3)) & 0x3f ;
int padlen = (index < 56) ? (56 - index) : (120 - index) ;
update (padding, padlen) ;
update (bits, 8) ;
return encode(state, 16) ;
}
// Encode the content.state array into 16 bytes array
private byte[] encode (int input[], int len) {
byte output[] = new byte[len] ;
int i = 0 ;
int j = 0 ;
for ( ; j < len ; i++, j+= 4) {
output[j] = (byte) ((input[i] ) & 0xff) ;
output[j+1] = (byte) ((input[i] >> 8 ) & 0xff) ;
output[j+2] = (byte) ((input[i] >> 16) & 0xff) ;
output[j+3] = (byte) ((input[i] >> 24) & 0xff) ;
}
return output ;
}
/**
* Get the digest for our input stream.
* This method constructs the input stream digest, and returns it, as
* a String, following the MD5 (rfc1321) algorithm
* @return An instance of String, giving the message digest.
* @exception IOException Thrown if the digestifier was unable to read
* the input stream.
*/
public byte[] getDigest ()
throws IOException
{
byte buffer[] = new byte[BUFFER_SIZE] ;
int got = -1 ;
if ( digest != null )
return digest ;
while ((got = in.read(buffer)) > 0 )
update (buffer, got) ;
this.digest = end () ;
return digest ;
}
/**
* Get the digest, for this string digestifier.
* This method doesn't throw any IOException, since it knows that the
* underlying stream was built from a String.
*/
public byte[] processString () {
if ( ! stringp )
throw new RuntimeException (this.getClass().getName()
+ "[processString]"
+ " not a string.") ;
try {
return getDigest() ;
} catch (IOException ex) {
}
throw new RuntimeException (this.getClass().getName()
+ "[processString]"
+ ": implementation error.") ;
}
/**
* Get the digest, as a proper string.
*/
public String getStringDigest() {
if ( digest == null )
throw new RuntimeException (this.getClass().getName()
+ "[getStringDigest]"
+ ": called before processing.") ;
return stringify (digest) ;
}
/**
* Construct a digestifier for the given input stream.
* @param in The input stream to be digestified.
*/
public Md5 (InputStream in) {
this.stringp = false ;
this.in = in ;
this.state = new int[4] ;
this.buffer = new byte[64] ;
this.count = 0 ;
state[0] = 0x67452301;
state[1] = 0xefcdab89;
state[2] = 0x98badcfe;
state[3] = 0x10325476;
}
public String parseToValue(byte b[]){
return stringify(b);
}