AMPS:MD5模組源碼解讀

  MD5是用於確保資訊傳輸完整一致性的一個雜湊演算法。

 其演算法思想如下（摘自維基百科）：

    MD5是輸入不定長度資訊，輸出固定長度128-bits的演算法。經過程式流程，產生四個32位元據，最後聯合起來成為一個128-bits散列。基本方式為，求餘、取餘、調整長度、與連結變數進行迴圈運算。得出結果。

 是 XOR, AND, OR , NOT 的符號。

 一個MD5運算— 由類似的64次迴圈構成，分成4組16次。F 一個非線性函數；一個函數運算一次。Mi 表示一個
32-bits 的輸入資料，Ki表示一個
32-bits 常數，用來完成每次不同的計算。

  

 下面是AMPS中MD5模組的源碼(說真的，演算法細節上還沒完全理解清楚)

AMPS_MD5.h

#ifndef __HEADER_AMPS_MD5_H#define __HEADER_AMPS_MD5_H#ifdef __cplusplusextern "C" {#endif#include "AMPS_Defines.h"#include "AMPS_LinkList.h"typedef struct _AMPSMD5Context      t_AMPSMD5Context;struct _AMPSMD5Context{unsigned intpunTotal[2];unsigned intpunState[4];unsigned charpuchBuffer[64];};void* AMD5_Init(void* r_pvAMPSContext);void AMD5_Cleanup(void* r_pvAMPSContext, void* r_pvAMPSMD5Context);int AMD5_Update(void* r_pvAMPSContext, void* r_pvAMPSMD5Context, unsigned char* r_puchData, int r_nDataLength);int AMD5_Final(void* r_pvAMPSContext, void* r_pvAMPSMD5Context, unsigned char* r_puchMD5Hash);#ifdef __cplusplus}#endif#endif //__HEADER_AMPS_HEAP_H

AMPS_MD5.c

#include "AMPS_Core.h"#include "AMPS_Defines.h"#include "AMPS_MemMgt.h"#include "AMPS_MD5.h"#include "AMPS_LinkList.h"#define GET_UINT32(n,b,i)                       \{                                               \(n) = ( (unsigned int) (b)[(i)    ]       )       \| ( (unsigned int) (b)[(i) + 1] <<  8 )       \| ( (unsigned int) (b)[(i) + 2] << 16 )       \| ( (unsigned int) (b)[(i) + 3] << 24 );      \}#define PUT_UINT32(n,b,i)                       \{                                               \(b)[(i)    ] = (unsigned char) ( (n)       );       \(b)[(i) + 1] = (unsigned char) ( (n) >>  8 );       \(b)[(i) + 2] = (unsigned char) ( (n) >> 16 );       \(b)[(i) + 3] = (unsigned char) ( (n) >> 24 );       \}/*****************************************************************函數名稱: AMD5_Init功能描述: MD5模組初始化入參::      void* r_pvAMPSContext AMPS應用上下文出參:      傳回值:      int*****************************************************************/void* AMD5_Init(void* r_pvAMPSContext){t_AMPSMD5Context* poAMPSMD5Context = NULL;TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");poAMPSMD5Context = (t_AMPSMD5Context*)AMPS_InternalMalloc(sizeof(t_AMPSMD5Context));if(NULL == poAMPSMD5Context){TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_ERROR, "AMPS_InternalMalloc failed for poMD5Context.\n");return NULL;}poAMPSMD5Context->punTotal[0] = 0;poAMPSMD5Context->punTotal[1] = 0;    /*四個32位被稱作連結變數*/poAMPSMD5Context->punState[0] = 0x67452301;poAMPSMD5Context->punState[1] = 0xEFCDAB89;poAMPSMD5Context->punState[2] = 0x98BADCFE;poAMPSMD5Context->punState[3] = 0x10325476;TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");return poAMPSMD5Context;}/*****************************************************************函數名稱: AMD5_Cleanup功能描述: MD5模組銷毀入參::      void* r_pvAMPSContext AMPS應用上下文      void* r_pvAMPSMD5Context MD5控制代碼出參:      傳回值:      int*****************************************************************/void AMD5_Cleanup(void* r_pvAMPSContext, void* r_pvAMPSMD5Context){TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_DEBUG, "AMPS_InternalFree called for r_pvAMPSMD5Context.\n");AMPS_InternalFree(r_pvAMPSMD5Context);TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");}/*****************************************************************函數名稱: AMD4_Process功能描述: MD4處理過程入參::      void* r_pvAMPSContext AMPS應用上下文      void* r_pvAMPSMD5Context MD5控制代碼      unsigned char r_puchData[64] 64位二進位表示的填充資訊出參:      傳回值:      int*****************************************************************/void AMD4_Process(void* r_pvAMPSContext, void* r_pvAMPSMD5Context, unsigned char r_puchData[64]){t_AMPSMD5Context* poAMPSMD5Context = r_pvAMPSMD5Context;unsigned int X[16], A, B, C, D;TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");GET_UINT32( X[0],  r_puchData,  0 );GET_UINT32( X[1],  r_puchData,  4 );GET_UINT32( X[2],  r_puchData,  8 );GET_UINT32( X[3],  r_puchData, 12 );GET_UINT32( X[4],  r_puchData, 16 );GET_UINT32( X[5],  r_puchData, 20 );GET_UINT32( X[6],  r_puchData, 24 );GET_UINT32( X[7],  r_puchData, 28 );GET_UINT32( X[8],  r_puchData, 32 );GET_UINT32( X[9],  r_puchData, 36 );GET_UINT32( X[10], r_puchData, 40 );GET_UINT32( X[11], r_puchData, 44 );GET_UINT32( X[12], r_puchData, 48 );GET_UINT32( X[13], r_puchData, 52 );GET_UINT32( X[14], r_puchData, 56 );GET_UINT32( X[15], r_puchData, 60 );#define S(x,n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))/*計算公式*/#define P(a,b,c,d,k,s,t)                                \{                                                       \a += F(b,c,d) + X[k] + t; a = S(a,s) + b;           \}A = poAMPSMD5Context->punState[0];B = poAMPSMD5Context->punState[1];C = poAMPSMD5Context->punState[2];D = poAMPSMD5Context->punState[3];/*第一輪*/#define F(x,y,z) (z ^ (x & (y ^ z)))P( A, B, C, D,  0,  7, 0xD76AA478 );P( D, A, B, C,  1, 12, 0xE8C7B756 );P( C, D, A, B,  2, 17, 0x242070DB );P( B, C, D, A,  3, 22, 0xC1BDCEEE );P( A, B, C, D,  4,  7, 0xF57C0FAF );P( D, A, B, C,  5, 12, 0x4787C62A );P( C, D, A, B,  6, 17, 0xA8304613 );P( B, C, D, A,  7, 22, 0xFD469501 );P( A, B, C, D,  8,  7, 0x698098D8 );P( D, A, B, C,  9, 12, 0x8B44F7AF );P( C, D, A, B, 10, 17, 0xFFFF5BB1 );P( B, C, D, A, 11, 22, 0x895CD7BE );P( A, B, C, D, 12,  7, 0x6B901122 );P( D, A, B, C, 13, 12, 0xFD987193 );P( C, D, A, B, 14, 17, 0xA679438E );P( B, C, D, A, 15, 22, 0x49B40821 );#undef F/*第二輪*/#define F(x,y,z) (y ^ (z & (x ^ y)))P( A, B, C, D,  1,  5, 0xF61E2562 );P( D, A, B, C,  6,  9, 0xC040B340 );P( C, D, A, B, 11, 14, 0x265E5A51 );P( B, C, D, A,  0, 20, 0xE9B6C7AA );P( A, B, C, D,  5,  5, 0xD62F105D );P( D, A, B, C, 10,  9, 0x02441453 );P( C, D, A, B, 15, 14, 0xD8A1E681 );P( B, C, D, A,  4, 20, 0xE7D3FBC8 );P( A, B, C, D,  9,  5, 0x21E1CDE6 );P( D, A, B, C, 14,  9, 0xC33707D6 );P( C, D, A, B,  3, 14, 0xF4D50D87 );P( B, C, D, A,  8, 20, 0x455A14ED );P( A, B, C, D, 13,  5, 0xA9E3E905 );P( D, A, B, C,  2,  9, 0xFCEFA3F8 );P( C, D, A, B,  7, 14, 0x676F02D9 );P( B, C, D, A, 12, 20, 0x8D2A4C8A );#undef F/*第三輪*/#define F(x,y,z) (x ^ y ^ z)P( A, B, C, D,  5,  4, 0xFFFA3942 );P( D, A, B, C,  8, 11, 0x8771F681 );P( C, D, A, B, 11, 16, 0x6D9D6122 );P( B, C, D, A, 14, 23, 0xFDE5380C );P( A, B, C, D,  1,  4, 0xA4BEEA44 );P( D, A, B, C,  4, 11, 0x4BDECFA9 );P( C, D, A, B,  7, 16, 0xF6BB4B60 );P( B, C, D, A, 10, 23, 0xBEBFBC70 );P( A, B, C, D, 13,  4, 0x289B7EC6 );P( D, A, B, C,  0, 11, 0xEAA127FA );P( C, D, A, B,  3, 16, 0xD4EF3085 );P( B, C, D, A,  6, 23, 0x04881D05 );P( A, B, C, D,  9,  4, 0xD9D4D039 );P( D, A, B, C, 12, 11, 0xE6DB99E5 );P( C, D, A, B, 15, 16, 0x1FA27CF8 );P( B, C, D, A,  2, 23, 0xC4AC5665 );#undef F/*第四輪*/#define F(x,y,z) (y ^ (x | ~z))P( A, B, C, D,  0,  6, 0xF4292244 );P( D, A, B, C,  7, 10, 0x432AFF97 );P( C, D, A, B, 14, 15, 0xAB9423A7 );P( B, C, D, A,  5, 21, 0xFC93A039 );P( A, B, C, D, 12,  6, 0x655B59C3 );P( D, A, B, C,  3, 10, 0x8F0CCC92 );P( C, D, A, B, 10, 15, 0xFFEFF47D );P( B, C, D, A,  1, 21, 0x85845DD1 );P( A, B, C, D,  8,  6, 0x6FA87E4F );P( D, A, B, C, 15, 10, 0xFE2CE6E0 );P( C, D, A, B,  6, 15, 0xA3014314 );P( B, C, D, A, 13, 21, 0x4E0811A1 );P( A, B, C, D,  4,  6, 0xF7537E82 );P( D, A, B, C, 11, 10, 0xBD3AF235 );P( C, D, A, B,  2, 15, 0x2AD7D2BB );P( B, C, D, A,  9, 21, 0xEB86D391 );#undef FpoAMPSMD5Context->punState[0] += A;poAMPSMD5Context->punState[1] += B;poAMPSMD5Context->punState[2] += C;poAMPSMD5Context->punState[3] += D;TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");}/*****************************************************************函數名稱: AMD5_Update功能描述: MD5處理過程入參::      void* r_pvAMPSContext AMPS應用上下文      void* r_pvAMPSMD5Context MD5控制代碼      unsigned char r_puchData[64] 64位二進位表示的填充資訊      int r_nDataLength 資料長度出參:      傳回值:      int*****************************************************************/int AMD5_Update(void* r_pvAMPSContext, void* r_pvAMPSMD5Context, unsigned char* r_puchData, int r_nDataLength){t_AMPSMD5Context* poAMPSMD5Context = r_pvAMPSMD5Context;unsigned int left, fill;TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");if( ! r_nDataLength ) return AMPS_ERROR_FAILURE;left = poAMPSMD5Context->punTotal[0] & 0x3F;fill = 64 - left;poAMPSMD5Context->punTotal[0] += r_nDataLength;poAMPSMD5Context->punTotal[0] &= 0xFFFFFFFF;if( poAMPSMD5Context->punTotal[0] < (unsigned int)r_nDataLength )poAMPSMD5Context->punTotal[1]++;if( left && (unsigned int)r_nDataLength >= fill ){memcpy((void*)(poAMPSMD5Context->puchBuffer + left), (void*)r_puchData, fill );AMD4_Process(r_pvAMPSContext, poAMPSMD5Context, poAMPSMD5Context->puchBuffer );r_nDataLength -= fill;r_puchData  += fill;left = 0;}while( r_nDataLength >= 64 ){AMD4_Process(r_pvAMPSContext, poAMPSMD5Context, r_puchData);r_nDataLength -= 64;r_puchData  += 64;}if( r_nDataLength ){memcpy((void*)(poAMPSMD5Context->puchBuffer + left), (void*)r_puchData, r_nDataLength );}TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");return AMPS_SUCCESS;}/*64位填充資訊*/static unsigned char md5_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};/*****************************************************************函數名稱: AMD5_Final功能描述: MD5計算函數入參::      void* r_pvAMPSContext AMPS應用上下文      void* r_pvAMPSMD5Context MD5控制代碼      unsigned char* r_puchMD5Hash md5值出參:      unsigned char* r_puchMD5Hash md5值      傳回值:      int*****************************************************************/int AMD5_Final(void* r_pvAMPSContext, void* r_pvAMPSMD5Context, unsigned char* r_puchMD5Hash){t_AMPSMD5Context* poAMPSMD5Context = r_pvAMPSMD5Context;unsigned int last, padn;unsigned int high, low;unsigned char msglen[8];TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Entering.\n");high = ( poAMPSMD5Context->punTotal[0] >> 29 )| ( poAMPSMD5Context->punTotal[1] <<  3 );low  = ( poAMPSMD5Context->punTotal[0] <<  3 );PUT_UINT32( low,  msglen, 0 );PUT_UINT32( high, msglen, 4 );last = poAMPSMD5Context->punTotal[0] & 0x3F;padn = ( last < 56 ) ? ( 56 - last ) : ( 120 - last );AMD5_Update(r_pvAMPSContext, poAMPSMD5Context, md5_padding, padn );AMD5_Update(r_pvAMPSContext, poAMPSMD5Context, msglen, 8 );PUT_UINT32( poAMPSMD5Context->punState[0], r_puchMD5Hash,  0 );PUT_UINT32( poAMPSMD5Context->punState[1], r_puchMD5Hash,  4 );PUT_UINT32( poAMPSMD5Context->punState[2], r_puchMD5Hash,  8 );PUT_UINT32( poAMPSMD5Context->punState[3], r_puchMD5Hash, 12 );TRACE( MD5_TRACE_ID(r_pvAMPSContext), AMPS_TRACE_LEVEL_INFO, "Leaving.\n");return AMPS_SUCCESS;}