md5checksum.h

通用SP及网关使用

   significant) bit of each byte listed first. Similarly, a sequence of
   bytes can be interpreted as a sequence of 32-bit words, where each
   consecutive group of four bytes is interpreted as a word with the
   low-order (least significant) byte given first.
   Let x_i denote "x sub i". If the subscript is an expression, we
   surround it in braces, as in x_{i+1}. Similarly, we use ^ for
   superscripts (exponentiation), so that x^i denotes x to the i-th   power.
   Let the symbol "+" denote addition of words (i.e., modulo-2^32
   addition). Let X <<< s denote the 32-bit value obtained by circularly
   shifting (rotating) X left by s bit positions. Let not(X) denote the
   bit-wise complement of X, and let X v Y denote the bit-wise OR of X
   and Y. Let X xor Y denote the bit-wise XOR of X and Y, and let XY
   denote the bit-wise AND of X and Y.


   3. MD5 Algorithm Description
   We begin by supposing that we have a b-bit message as input, and that
   we wish to find its message digest. Here b is an arbitrary
   nonnegative integer; b may be zero, it need not be a multiple of
   eight, and it may be arbitrarily large. We imagine the bits of the
   message written down as follows:          m_0 m_1 ... m_{b-1}
   The following five steps are performed to compute the message digest
   of the message.
   
   3.1 Step 1. Append Padding Bits
   The message is "padded" (extended) so that its length (in bits) is
   congruent to 448, modulo 512. That is, the message is extended so
   that it is just 64 bits shy of being a multiple of 512 bits long.
   Padding is always performed, even if the length of the message is
   already congruent to 448, modulo 512.
   Padding is performed as follows: a single "1" bit is appended to the
   message, and then "0" bits are appended so that the length in bits of
   the padded message becomes congruent to 448, modulo 512. In all, at
   least one bit and at most 512 bits are appended.

   3.2 Step 2. Append Length
   A 64-bit representation of b (the length of the message before the
   padding bits were added) is appended to the result of the previous
   step. In the unlikely event that b is greater than 2^64, then only
   the low-order 64 bits of b are used. (These bits are appended as two
   32-bit words and appended low-order word first in accordance with the
   previous conventions.)
   At this point the resulting message (after padding with bits and with
   b) has a length that is an exact multiple of 512 bits. Equivalently,
   this message has a length that is an exact multiple of 16 (32-bit)
   words. Let M[0 ... N-1] denote the words of the resulting message,
   where N is a multiple of 16.
   
   3.3 Step 3. Initialize MD Buffer
   A four-word buffer (A,B,C,D) is used to compute the message digest.
   Here each of A, B, C, D is a 32-bit register. These registers are
   initialized to the following values in hexadecimal, low-order bytes   first):
          word A: 01 23 45 67          word B: 89 ab cd ef
          word C: fe dc ba 98          word D: 76 54 32 10

   3.4 Step 4. Process Message in 16-Word Blocks
   We first define four auxiliary functions that each take as input
   three 32-bit words and produce as output one 32-bit word.
          F(X,Y,Z) = XY v not(X) Z          G(X,Y,Z) = XZ v Y not(Z)
          H(X,Y,Z) = X xor Y xor Z          I(X,Y,Z) = Y xor (X v not(Z))
   In each bit position F acts as a conditional: if X then Y else Z.
   The function F could have been defined using + instead of v since XY
   and not(X)Z will never have 1's in the same bit position.) It is
   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
		 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

   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.
   
   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.

   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


   The level of security discussed in this memo is considered to be
   sufficient for implementing very high security hybrid digital-
   signature schemes based on MD5 and a public-key cryptosystem.
   Author's Address
   Ronald L. Rivest   Massachusetts Institute of Technology
   Laboratory for Computer Science   NE43-324   545 Technology Square
   Cambridge, MA  02139-1986   Phone: [phone]
   EMail: [e-mail]


*****************************************************************************************/
class CMD5Checksum  
{
public:
	//interface functions for the RSA MD5 calculation
	static void GetMD5(BYTE* pBuf, UINT nLength, BYTE *pMD5);

protected:
	//constructor/destructor
	CMD5Checksum();
	virtual ~CMD5Checksum() {};

	//RSA MD5 implementation
	void Transform(BYTE Block[64]);
	void Update(BYTE* Input, ULONG nInputLen);
	void Final(BYTE *);
	inline DWORD RotateLeft(DWORD x, int n);
	inline void FF( DWORD& A, DWORD B, DWORD C, DWORD D, DWORD X, DWORD S, DWORD T);
	inline void GG( DWORD& A, DWORD B, DWORD C, DWORD D, DWORD X, DWORD S, DWORD T);
	inline void HH( DWORD& A, DWORD B, DWORD C, DWORD D, DWORD X, DWORD S, DWORD T);
	inline void II( DWORD& A, DWORD B, DWORD C, DWORD D, DWORD X, DWORD S, DWORD T);

	//utility functions
	void DWordToByte(BYTE* Output, DWORD* Input, UINT nLength);
	void ByteToDWord(DWORD* Output, BYTE* Input, UINT nLength);

private:
	BYTE  m_lpszBuffer[64];		//input buffer
	ULONG m_nCount[2];			//number of bits, modulo 2^64 (lsb first)
	ULONG m_lMD5[4];			//MD5 checksum
};