unitfymd5.pas

MD5加密与解密的说明文件与,烦琐的加密不能解密

   interesting to note that if the bits of X, Y, and Z are independent
   and unbiased, the each bit of F(X,Y,Z) will be independent and
   unbiased.

   The functions G, H, and I are similar to the function F, in that they
   act in "bitwise parallel" to produce their output from the bits of X,
   Y, and Z, in such a manner that if the corresponding bits of X, Y,
   and Z are independent and unbiased, then each bit of G(X,Y,Z),
   H(X,Y,Z), and I(X,Y,Z) will be independent and unbiased. Note that
   the function H is the bit-wise "xor" or "parity" function of its
   inputs.

   This step uses a 64-element table T[1 ... 64] constructed from the
   sine function. Let T[i] denote the i-th element of the table, which
   is equal to the integer part of 4294967296 times abs(sin(i)), where i
   is in radians. The elements of the table are given in the appendix.

   Do the following:

   /* Process each 16-word block. */
   For i = 0 to N/16-1 do

     /* Copy block i into X. */
     For j = 0 to 15 do
       Set X[j] to M[i*16+j].
     end /* of loop on j */

     /* Save A as AA, B as BB, C as CC, and D as DD. */
     AA = A
     BB = B



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RFC 1321              MD5 Message-Digest Algorithm            April 1992


     CC = C
     DD = D

     /* Round 1. */
     /* Let [abcd k s i] denote the operation
          a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
     /* Do the following 16 operations. */
     [ABCD  0  7  1]  [DABC  1 12  2]  [CDAB  2 17  3]  [BCDA  3 22  4]
     [ABCD  4  7  5]  [DABC  5 12  6]  [CDAB  6 17  7]  [BCDA  7 22  8]
     [ABCD  8  7  9]  [DABC  9 12 10]  [CDAB 10 17 11]  [BCDA 11 22 12]
     [ABCD 12  7 13]  [DABC 13 12 14]  [CDAB 14 17 15]  [BCDA 15 22 16]

     /* Round 2. */
     /* Let [abcd k s i] denote the operation
          a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */
     /* Do the following 16 operations. */
     [ABCD  1  5 17]  [DABC  6  9 18]  [CDAB 11 14 19]  [BCDA  0 20 20]
     [ABCD  5  5 21]  [DABC 10  9 22]  [CDAB 15 14 23]  [BCDA  4 20 24]
     [ABCD  9  5 25]  [DABC 14  9 26]  [CDAB  3 14 27]  [BCDA  8 20 28]
     [ABCD 13  5 29]  [DABC  2  9 30]  [CDAB  7 14 31]  [BCDA 12 20 32]

     /* Round 3. */
     /* Let [abcd k s t] denote the operation
          a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */
     /* Do the following 16 operations. */
     [ABCD  5  4 33]  [DABC  8 11 34]  [CDAB 11 16 35]  [BCDA 14 23 36]
     [ABCD  1  4 37]  [DABC  4 11 38]  [CDAB  7 16 39]  [BCDA 10 23 40]
     [ABCD 13  4 41]  [DABC  0 11 42]  [CDAB  3 16 43]  [BCDA  6 23 44]
     [ABCD  9  4 45]  [DABC 12 11 46]  [CDAB 15 16 47]  [BCDA  2 23 48]

     /* Round 4. */
     /* Let [abcd k s t] denote the operation
          a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */
     /* Do the following 16 operations. */
     [ABCD  0  6 49]  [DABC  7 10 50]  [CDAB 14 15 51]  [BCDA  5 21 52]
     [ABCD 12  6 53]  [DABC  3 10 54]  [CDAB 10 15 55]  [BCDA  1 21 56]
     [ABCD  8  6 57]  [DABC 15 10 58]  [CDAB  6 15 59]  [BCDA 13 21 60]
     [ABCD  4  6 61]  [DABC 11 10 62]  [CDAB  2 15 63]  [BCDA  9 21 64]

     /* Then perform the following additions. (That is increment each
        of the four registers by the value it had before this block
        was started.) */
     A = A + AA
     B = B + BB
     C = C + CC
     D = D + DD

   end /* of loop on i */



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RFC 1321              MD5 Message-Digest Algorithm            April 1992


3.5 Step 5. Output

   The message digest produced as output is A, B, C, D. That is, we
   begin with the low-order byte of A, and end with the high-order byte
   of D.

   This completes the description of MD5. A reference implementation in
   C is given in the appendix.

4. Summary

   The MD5 message-digest algorithm is simple to implement, and provides
   a "fingerprint" or message digest of a message of arbitrary length.
   It is conjectured that the difficulty of coming up with two messages
   having the same message digest is on the order of 2^64 operations,
   and that the difficulty of coming up with any message having a given
   message digest is on the order of 2^128 operations. The MD5 algorithm
   has been carefully scrutinized for weaknesses. It is, however, a
   relatively new algorithm and further security analysis is of course
   justified, as is the case with any new proposal of this sort.

5. Differences Between MD4 and MD5

     The following are the differences between MD4 and MD5:

       1.   A fourth round has been added.

       2.   Each step now has a unique additive constant.

       3.   The function g in round 2 was changed from (XY v XZ v YZ) to
       (XZ v Y not(Z)) to make g less symmetric.

       4.   Each step now adds in the result of the previous step.  This
       promotes a faster "avalanche effect".

       5.   The order in which input words are accessed in rounds 2 and
       3 is changed, to make these patterns less like each other.

       6.   The shift amounts in each round have been approximately
       optimized, to yield a faster "avalanche effect." The shifts in
       different rounds are distinct.










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RFC 1321              MD5 Message-Digest Algorithm            April 1992


References

   [1] Rivest, R., "The MD4 Message Digest Algorithm", RFC 1320, MIT and
       RSA Data Security, Inc., April 1992.

   [2] Rivest, R., "The MD4 message digest algorithm", in A.J.  Menezes
       and S.A. Vanstone, editors, Advances in Cryptology - CRYPTO '90
       Proceedings, pages 303-311, Springer-Verlag, 1991.

   [3] CCITT Recommendation X.509 (1988), "The Directory -
       Authentication Framework."

APPENDIX A - Reference Implementation

   This appendix contains the following files taken from RSAREF: A
   Cryptographic Toolkit for Privacy-Enhanced Mail:

     global.h -- global header file

     md5.h -- header file for MD5

     md5c.c -- source code for MD5

   For more information on RSAREF, send email to <[e-mail]>.

   The appendix also includes the following file:

     mddriver.c -- test driver for MD2, MD4 and MD5

   The driver compiles for MD5 by default but can compile for MD2 or MD4
   if the symbol MD is defined on the C compiler command line as 2 or 4.

   The implementation is portable and should work on many different
   plaforms. However, it is not difficult to optimize the implementation
   on particular platforms, an exercise left to the reader. For example,
   on "little-endian" platforms where the lowest-addressed byte in a 32-
   bit word is the least significant and there are no alignment
   restrictions, the call to Decode in MD5Transform can be replaced with
   a typecast.

A.1 global.h

/* GLOBAL.H - RSAREF types and constants
 */

/* PROTOTYPES should be set to one if and only if the compiler supports
  function argument prototyping.
The following makes PROTOTYPES default to 0 if it has not already



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  been defined with C compiler flags.
 */
#ifndef PROTOTYPES
#define PROTOTYPES 0
#endif

/* POINTER defines a generic pointer type */
typedef unsigned char *POINTER;

/* UINT2 defines a two byte word */
typedef unsigned short int UINT2;

/* UINT4 defines a four byte word */
typedef unsigned long int UINT4;

/* PROTO_LIST is defined depending on how PROTOTYPES is defined above.
If using PROTOTYPES, then PROTO_LIST returns the list, otherwise it
  returns an empty list.
 */
#if PROTOTYPES
#define PROTO_LIST(list) list
#else
#define PROTO_LIST(list) ()
#endif

A.2 md5.h

/* MD5.H - header file for MD5C.C
 */

/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
rights reserved.

License to copy and use this software is granted provided that it
is identified as the "RSA Data Security, Inc. MD5 Message-Digest
Algorithm" in all material mentioning or referencing this software
or this function.

License is also granted to make and use derivative works provided
that such works are identified as "derived from the RSA Data
Security, Inc. MD5 Message-Digest Algorithm" in all material
mentioning or referencing the derived work.

RSA Data Security, Inc. makes no representations concerning either
the merchantability of this software or the suitability of this
software for any particular purpose. It is provided "as is"
without express or implied warranty of any kind.




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RFC 1321              MD5 Message-Digest Algorithm            April 1992


These notices must be retained in any copies of any part of this
documentation and/or software.
 */

/* MD5 context. */
typedef struct {
  UINT4 state[4];                                   /* state (ABCD) */
  UINT4 count[2];        /* number of bits, modulo 2^64 (lsb first) */
  unsigned char buffer[64];                         /* input buffer */
} MD5_CTX;

void MD5Init PROTO_LIST ((MD5_CTX *));
void MD5Update PROTO_LIST
  ((MD5_CTX *, unsigned char *, unsigned int));
void MD5Final PROTO_LIST ((unsigned char [16], MD5_CTX *));

A.3 md5c.c

/* MD5C.C - RSA Data Security, Inc., MD5 message-digest algorithm
 */

/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
rights reserved.

License to copy and use this software is granted provided that it
is identified as the "RSA Data Security, Inc. MD5 Message-Digest
Algorithm" in all material mentioning or referencing this software
or this function.

License is also granted to make and use derivative works provided
that such works are identified as "derived from the RSA Data
Security, Inc. MD5 Message-Digest Algorithm" in all material
mentioning or referencing the derived work.

RSA Data Security, Inc. makes no representations concerning either
the merchantability of this software or the suitability of this
software for any particular purpose. It is provided "as is"
without express or implied warranty of any kind.

These notices must be retained in any copies of any part of this
documentation and/or software.
 */

#include "global.h"
#include "md5.h"

/* Constants for MD5Transform routine.
 */



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RFC 1321              MD5 Message-Digest Algorithm            April 1992


#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

static void MD5Transform PROTO_LIST ((UINT4 [4], unsigned char [64]));
static void Encode PROTO_LIST
  ((unsigned char *, UINT4 *, unsigned int));
static void Decode PROTO_LIST
  ((UINT4 *, unsigned char *, unsigned int));
static void MD5_memcpy PROTO_LIST ((POINTER, POINTER, unsigned int));
static void MD5_memset PROTO_LIST ((POINTER, int, unsigned int));

static unsigned char PADDING[64] = {
  0x80, 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
};

/* F, G, H and I are basic MD5 functions.
 */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

/* ROTATE_LEFT rotates x left n bits.
 */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
Rotation is separate from addition to prevent recomputation.
 */
#define FF(a, b, c, d, x, s, ac) { \
 (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
 (a) = ROTATE_LEFT ((a), (s)); \