I need help... I want to parallelize the MD5 algorithm using OpenMP in C++.

Have you tried anything by now? If yes, could you show us what you did and where you got stuck?

I want a more efficient code than this. I want to use the nested directive..
I want to parallelize the (for) loops in the Encode and Decode functions.

md5.cpp:

#include <omp.h>
#include <assert.h>
#include <memory.h>
#include <stdio.h>
#include <string.h>
#include <iostream>
using namespace std;
#include "md5.h"


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
};

#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


// PrintMD5: Converts a completed md5 digest into a char* string.
char* PrintMD5(uchar md5Digest[16])
{
    char chBuffer[256];
    char chEach[10];
    int nCount;

    memset(chBuffer,0,256);
    memset(chEach, 0, 10);

    for (nCount = 0; nCount < 16; nCount++)
    {
        sprintf(chEach, "%02x", md5Digest[nCount]);
        strncat(chBuffer, chEach, sizeof(chEach));
    }

    return strdup(chBuffer);
}

// MD5String: Performs the MD5 algorithm on a char* string, returning
// the results as a char*.
char* MD5String(char* szString)
{
    int nLen = strlen(szString);
    md5 alg;

    alg.Update((unsigned char*)szString, (unsigned int)nLen);
    alg.Finalize();

    return PrintMD5(alg.Digest());

}

// MD5File: Performs the MD5 algorithm on a file (binar or text),
// returning the results as a char*.  Returns NULL if it fails.
char* MD5File(char* szFilename)
{
    FILE* file;
    md5 alg;
    int nLen;
    unsigned char chBuffer[1024];

    try
    {
        memset(chBuffer, 0, 1024);

        if ((file = fopen (szFilename, "rb")) != NULL)
        {
            while (nLen = fread (chBuffer, 1, 1024, file))
                alg.Update(chBuffer, nLen);

            alg.Finalize();

            fclose (file);

            return PrintMD5(alg.Digest());
        }
    }
    catch(...)
    {

    }

    return NULL; // failed
}


// md5::Init
// Initializes a new context.
void md5::Init()
{
    memset(m_Count, 0, 2 * sizeof(uint4));

    m_State[0] = 0x67452301;
    m_State[1] = 0xefcdab89;
    m_State[2] = 0x98badcfe;
    m_State[3] = 0x10325476;
}

// md5::Update
// MD5 block update operation. Continues an MD5 message-digest
// operation, processing another message block, and updating the
// context.
void md5::Update(uchar* chInput, uint4 nInputLen)
{
    int i, index, partLen;
    int nIL=nInputLen, chunk=10;

    // Compute number of bytes mod 64
    index = (unsigned int)((m_Count[0] >> 3) & 0x3F);

    // Update number of bits
    if ((m_Count[0] += (nInputLen << 3)) < (nInputLen << 3))
        m_Count[1]++;

    m_Count[1] += (nInputLen >> 29);
    partLen = 64 - index;

    // Transform as many times as possible.
    if (nInputLen >= partLen)
    {
        memcpy( &m_Buffer[index], chInput, partLen );
        Transform(m_Buffer);
        i=partLen;
        MyFunction(i,partLen,chInput,nIL);
       //for (i = partLen; i+63 < nIL; i += 64)
        //       Transform(&chInput[i]);    
        index = 0;
    }
    else
        i = 0;

  // Buffer remaining input
  memcpy( &m_Buffer[index], &chInput[i], nInputLen-i );  
}

//MyFunction
void md5::MyFunction(int i, int partLen, uchar* chInput, int nIL)
{
    omp_set_num_threads(5);
#pragma omp parallel shared(chInput, nIL, partLen)
    {

    #pragma omp for private(i) schedule(dynamic, 10)
        for(i=partLen;i<nIL;i += 64){
            Transform(&chInput[i]);

            #pragma omp critical
                {
                  if(i+63>=nIL){
                     nIL=i-1;
                  }
                }
        }
    }
}

// md5::Finalize
// MD5 finalization. Ends an MD5 message-digest operation, writing
// the message digest and zeroizing the context.
void md5::Finalize()
{
    uchar bits[8];
    uint4 index, padLen;
#pragma omp sections
    {
#pragma omp section
        {
    // Save number of bits
    Encode (bits, m_Count, 8);
        }
#pragma omp section
        {
    // Pad out to 56 mod 64
    index = (unsigned int)((m_Count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    Update(PADDING, padLen);
        }    
    }

    // Append length (before padding)
    Update (bits, 8);

    // Store state in digest
    Encode (m_Digest, m_State, 16);

    memset(m_Count, 0, 2 * sizeof(uint4));
    memset(m_State, 0, 4 * sizeof(uint4));
    memset(m_Buffer,0, 64 * sizeof(uchar));


}

// md5::Transform
// MD5 basic transformation. Transforms state based on block.
void md5::Transform (uchar* block)
{
    uint4 a = m_State[0], b = m_State[1], c = m_State[2], d = m_State[3], x[16];
    //omp_set_num_threads(4);

#pragma omp sections
     {
#pragma omp section
         {   
    Decode (x, block, 64);
         }
#pragma omp section
         {
  // Round 1        
  FF (a, b, c, d, x[ 0], S11, 0xd76aa478);
  FF (d, a, b, c, x[ 1], S12, 0xe8c7b756);
  FF (c, d, a, b, x[ 2], S13, 0x242070db);
  FF (b, c, d, a, x[ 3], S14, 0xc1bdceee);
  FF (a, b, c, d, x[ 4], S11, 0xf57c0faf);
  FF (d, a, b, c, x[ 5], S12, 0x4787c62a);
  FF (c, d, a, b, x[ 6], S13, 0xa8304613);
  FF (b, c, d, a, x[ 7], S14, 0xfd469501);
  FF (a, b, c, d, x[ 8], S11, 0x698098d8);
  FF (d, a, b, c, x[ 9], S12, 0x8b44f7af);
  FF (c, d, a, b, x[10], S13, 0xffff5bb1);
  FF (b, c, d, a, x[11], S14, 0x895cd7be);
  FF (a, b, c, d, x[12], S11, 0x6b901122);
  FF (d, a, b, c, x[13], S12, 0xfd987193);
  FF (c, d, a, b, x[14], S13, 0xa679438e);
  FF (b, c, d, a, x[15], S14, 0x49b40821);
         }
#pragma omp section
         {
  // Round 2
  GG (a, b, c, d, x[ 1], S21, 0xf61e2562);
  GG (d, a, b, c, x[ 6], S22, 0xc040b340);
  GG (c, d, a, b, x[11], S23, 0x265e5a51);
  GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa);
  GG (a, b, c, d, x[ 5], S21, 0xd62f105d);
  GG (d, a, b, c, x[10], S22,  0x2441453);
  GG (c, d, a, b, x[15], S23, 0xd8a1e681);
  GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8);
  GG (a, b, c, d, x[ 9], S21, 0x21e1cde6);
  GG (d, a, b, c, x[14], S22, 0xc33707d6);
  GG (c, d, a, b, x[ 3], S23, 0xf4d50d87);
  GG (b, c, d, a, x[ 8], S24, 0x455a14ed);
  GG (a, b, c, d, x[13], S21, 0xa9e3e905);
  GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8);
  GG (c, d, a, b, x[ 7], S23, 0x676f02d9);
  GG (b, c, d, a, x[12], S24, 0x8d2a4c8a);
         }
#pragma omp section
         {
  // Round 3
  HH (a, b, c, d, x[ 5], S31, 0xfffa3942);
  HH (d, a, b, c, x[ 8], S32, 0x8771f681);
  HH (c, d, a, b, x[11], S33, 0x6d9d6122);
  HH (b, c, d, a, x[14], S34, 0xfde5380c);
  HH (a, b, c, d, x[ 1], S31, 0xa4beea44);
  HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9);
  HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60);
  HH (b, c, d, a, x[10], S34, 0xbebfbc70);
  HH (a, b, c, d, x[13], S31, 0x289b7ec6);
  HH (d, a, b, c, x[ 0], S32, 0xeaa127fa);
  HH (c, d, a, b, x[ 3], S33, 0xd4ef3085);
  HH (b, c, d, a, x[ 6], S34,  0x4881d05);
  HH (a, b, c, d, x[ 9], S31, 0xd9d4d039);
  HH (d, a, b, c, x[12], S32, 0xe6db99e5);
  HH (c, d, a, b, x[15], S33, 0x1fa27cf8);
  HH (b, c, d, a, x[ 2], S34, 0xc4ac5665);
         }
#pragma omp section
         {
  // Round 4
  II (a, b, c, d, x[ 0], S41, 0xf4292244);
  II (d, a, b, c, x[ 7], S42, 0x432aff97);
  II (c, d, a, b, x[14], S43, 0xab9423a7);
  II (b, c, d, a, x[ 5], S44, 0xfc93a039);
  II (a, b, c, d, x[12], S41, 0x655b59c3);
  II (d, a, b, c, x[ 3], S42, 0x8f0ccc92);
  II (c, d, a, b, x[10], S43, 0xffeff47d);
  II (b, c, d, a, x[ 1], S44, 0x85845dd1);
  II (a, b, c, d, x[ 8], S41, 0x6fa87e4f);
  II (d, a, b, c, x[15], S42, 0xfe2ce6e0);
  II (c, d, a, b, x[ 6], S43, 0xa3014314);
  II (b, c, d, a, x[13], S44, 0x4e0811a1);
  II (a, b, c, d, x[ 4], S41, 0xf7537e82);
  II (d, a, b, c, x[11], S42, 0xbd3af235);
  II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb);
  II (b, c, d, a, x[ 9], S44, 0xeb86d391);
         }
     }
  m_State[0] += a;
  m_State[1] += b;
  m_State[2] += c;
  m_State[3] += d;

  memset(x, 0, sizeof(x));
}

// md5::Encode
// Encodes input (uint4) into output (uchar). Assumes nLength is
// a multiple of 4.
void md5::Encode(uchar* dest, uint4* src, uint4 nLength)
{
    uint4 i, j;

    assert(nLength % 4 == 0);

    for (i = 0, j = 0; j < nLength; i++, j += 4)
    {
        dest[j] = (uchar)(src[i] & 0xff);
        dest[j+1] = (uchar)((src[i] >> 8) & 0xff);
        dest[j+2] = (uchar)((src[i] >> 16) & 0xff);
        dest[j+3] = (uchar)((src[i] >> 24) & 0xff);
    }
}

// md5::Decode
// Decodes input (uchar) into output (uint4). Assumes nLength is
// a multiple of 4.
void md5::Decode(uint4* dest, uchar* src, uint4 nLength)
{
    uint4 i, j;
    int chunk=4; 

    assert(nLength % 4 == 0);

  for (i = 0, j = 0; j < nLength; i++, j += 4)
    {
        dest[i] = ((uint4)src[j]) | (((uint4)src[j+1])<<8) |
                  (((uint4)src[j+2])<<16) | (((uint4)src[j+3])<<24);
    }

}

test.cpp:

#include <stdio.h>
#include <omp.h>
#include <iostream>
using namespace std;
#include "md5.h"


int main(void)
{
    int n;
    double time1, time2;
    time1=omp_get_wtime();
    cout << "\n The MD5 of 'zzzzzz' is : ";
    cout << MD5String("zzzzzz");
    cout << "\n";
    time2=omp_get_wtime();
    cout << "\n Time: " << time2-time1;
    cin >> n;

  return 0;
}

md5.h:

typedef unsigned       int uint4;
typedef unsigned short int uint2;
typedef unsigned      char uchar;

char* PrintMD5(uchar md5Digest[16]);
char* MD5String(char* szString);
char* MD5File(char* szFilename);

class md5
{
// Methods
public:
    md5() { Init(); }
    void    Init();
    void    Update(uchar* chInput, uint4 nInputLen);
    void    Finalize();
    uchar*  Digest() { return m_Digest; }

private:

    void    Transform(uchar* block);
    void    Encode(uchar* dest, uint4* src, uint4 nLength);
    void    Decode(uint4* dest, uchar* src, uint4 nLength);
    void    MyFunction(int i, int partLen, uchar* chInput, int nIL);


    inline  uint4   rotate_left(uint4 x, uint4 n)
                     { return ((x << n) | (x >> (32-n))); }

    inline  uint4   F(uint4 x, uint4 y, uint4 z)
                     { return ((x & y) | (~x & z)); }

    inline  uint4   G(uint4 x, uint4 y, uint4 z)
                     { return ((x & z) | (y & ~z)); }

    inline  uint4   H(uint4 x, uint4 y, uint4 z)
                     { return (x ^ y ^ z); }

    inline  uint4   I(uint4 x, uint4 y, uint4 z)
                     { return (y ^ (x | ~z)); }

    inline  void    FF(uint4& a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac)
                     { a += F(b, c, d) + x + ac; a = rotate_left(a, s); a += b; }

    inline  void    GG(uint4& a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac)
                     { a += G(b, c, d) + x + ac; a = rotate_left(a, s); a += b; }

    inline  void    HH(uint4& a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac)
                     { a += H(b, c, d) + x + ac; a = rotate_left(a, s); a += b; }

    inline  void    II(uint4& a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac)
                     { a += I(b, c, d) + x + ac; a = rotate_left(a, s); a += b; }

// Data
private:
    uint4       m_State[4];
    uint4       m_Count[2];
    uchar       m_Buffer[64];
    uchar       m_Digest[16];
    uchar       m_Finalized;

};
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