md5.cpp

#include "md5.h"
#include <byte_def.h>
#include <stdlib.h>


#define BITS_PER_BLOCK 512
#define MODULO_BITS 448
#define BITS_PER_BYTE 8
#define BYTES_PER_BLOCK (BITS_PER_BLOCK/BITS_PER_BYTE)
#define MODULO_BYTES (MODULO_BITS/BITS_PER_BYTE)
#define WORD_SIZE 4
#define WORDS_PER_BLOCK (BYTES_PER_BLOCK/WORD_SIZE)
#define NUM_ROUNDS 4
#define OPS_PER_ROUND 16
#define TOTAL_OPS (NUM_ROUNDS*OPS_PER_ROUND)
#define PADDING_LEAD 128
#define PADDING_TAIL 0
#define A_INIT 0x67452301
#define B_INIT 0xEFCDAB89
#define C_INIT 0x98BADCFE
#define D_INIT 0x10325476
#define CIRCULAR_LEFT_SHIFT(x,s) (((x)<<(s))|((x)>>((WORD_SIZE*BITS_PER_BYTE)-(s))))


int per_round_shift []={7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21};
int sine_table []={0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501, 0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be, 0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821, 0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8, 0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a, 0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c, 0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70, 0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05, 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665, 0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1, 0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, 0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391};


Hash::MD5Result::MD5Result () {

    High=D_INIT;
    HighMid=C_INIT;
    LowMid=B_INIT;
    Low=A_INIT;

}


void Hash::MD5Block (const void * p, MD5Result * state) {

    unsigned int a=state->Low;
    unsigned int b=state->LowMid;
    unsigned int c=state->HighMid;
    unsigned int d=state->High;

    for (int i=0;i<TOTAL_OPS;++i) {

        unsigned int f;
        unsigned int g;

        switch (i/OPS_PER_ROUND) {

            case 0:

                f=(b&c)|((~b)&d);
                g=i;

                break;

            case 1:

                f=(d&b)|((~d)&c);
                g=((5*i)+1)%16;

                break;

            case 2:

                f=b^c^d;
                g=((3*i)+5)%16;

                break;

            default:    //  3

                f=c^(b|(~d));
                g=(7*i)%16;

                break;

        }

        unsigned int letter_shift_temp=d;
        d=c;
        c=b;
        unsigned int circ_shift=a+f+sine_table[i]+((unsigned int *)p)[g];
        b+=CIRCULAR_LEFT_SHIFT(circ_shift,per_round_shift[i]);
        a=letter_shift_temp;

    }

    state->Low+=a;
    state->LowMid+=b;
    state->HighMid+=c;
    state->High+=d;

}


Hash::MD5Result Hash::MD5 (const void * p, int byte_len) {

    MD5Result returnthis;

    int bytes_remaining=byte_len;
    Byte * q=(Byte *)const_cast<void *>(p);

    for (
        ;
        bytes_remaining>=BYTES_PER_BLOCK;
        q+=BYTES_PER_BLOCK,bytes_remaining-=BYTES_PER_BLOCK
    ) MD5Block(q,&returnthis);

    int size_r=(
        (bytes_remaining>=MODULO_BYTES)
            ?   (BYTES_PER_BLOCK*2)
            :   BYTES_PER_BLOCK
    );

    Byte * r=(Byte *)malloc(sizeof(Byte)*size_r);

    int i=0;

    for (
        ;
        bytes_remaining>0;
        --bytes_remaining,++i
    ) r[i]=q[i];

    for (
        int padding_start=i;
        i<(size_r-sizeof(unsigned long long));
        ++i
    ) r[i]=(
        (i==padding_start)
            ?   PADDING_LEAD
            :   PADDING_TAIL
    );

    unsigned long long append_len=
        ((unsigned long long)byte_len)*
        ((unsigned long long)BITS_PER_BYTE);

    for (
        int n=0;
        i<size_r;
        ++i,++n
    ) r[i]=((Byte *)&append_len)[n];

    for (
        int n=0;
        n<(size_r/BYTES_PER_BLOCK);
        ++n
    ) MD5Block(
        r+(BYTES_PER_BLOCK*n),
        &returnthis
    );

    free(r);

    return returnthis;

}