MD5

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <memory.h>

namespace encrypt {

#ifndef uint8
#define uint8  unsigned char
#endif

#ifndef uint32
#define uint32 unsigned long int
#endif

#define MD5_DATA_LEN							16

    //////////////////////////////////////////////////////////////////////////////////
    // Md5
    class Md5 {
    private:

        typedef struct __md5_context
        {
            uint32 total[2];
            uint32 state[4];
            uint8 buffer[64];
        } md5_context;

        uint8 md5_padding[64];

        void md5_starts(md5_context* ctx);
        void md5_update(md5_context* ctx, uint8* input, uint32 length);
        void md5_finish(md5_context* ctx, uint8 digest[MD5_DATA_LEN]);
        void md5_process(md5_context* ctx, uint8 data[64]);

    public:

        Md5();

        ~Md5();

        static void Get(uint8* input, uint8 digest[MD5_DATA_LEN]);
    };
}

int main()
{
    uint8 digest[MD5_DATA_LEN];

    encrypt::Md5::Get((uint8*)"a", digest);

    for (int i = 0; i < MD5_DATA_LEN; i++) {
        printf("%02X", digest[i]);
    }
    printf("\n");

    encrypt::Md5::Get((uint8*)"abc", digest);

    for (int i = 0; i < MD5_DATA_LEN; i++) {
        printf("%02X", digest[i]);
    }
    printf("\n");
    return 0;
}

/*

static char *msg[] =
{
    "",
    "a",
    "abc",
    "message digest",
    "abcdefghijklmnopqrstuvwxyz",
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
    "12345678901234567890123456789012345678901234567890123456789012" \
        "345678901234567890"
};

static char *val[] =
{
    "d41d8cd98f00b204e9800998ecf8427e",
    "0cc175b9c0f1b6a831c399e269772661",
    "900150983cd24fb0d6963f7d28e17f72",
    "f96b697d7cb7938d525a2f31aaf161d0",
    "c3fcd3d76192e4007dfb496cca67e13b",
    "d174ab98d277d9f5a5611c2c9f419d9f",
    "57edf4a22be3c955ac49da2e2107b67a"
};

*/

namespace encrypt {

#define GET_UINT32(n,b,i)                       \
{                                               \
    (n) = ( (uint32) (b)[(i)    ]       )       \
        | ( (uint32) (b)[(i) + 1] <<  8 )       \
        | ( (uint32) (b)[(i) + 2] << 16 )       \
        | ( (uint32) (b)[(i) + 3] << 24 );      \
}

#define PUT_UINT32(n,b,i)                       \
{                                               \
    (b)[(i)    ] = (uint8) ( (n)       );       \
    (b)[(i) + 1] = (uint8) ( (n) >>  8 );       \
    (b)[(i) + 2] = (uint8) ( (n) >> 16 );       \
    (b)[(i) + 3] = (uint8) ( (n) >> 24 );       \
}

    Md5::Md5() {
        memset(md5_padding, 0, 64);
        md5_padding[0] = 0x80;
    }

    Md5::~Md5() {
    }

    void Md5::md5_starts(md5_context* ctx)
    {
        ctx->total[0] = 0;
        ctx->total[1] = 0;

        ctx->state[0] = 0x67452301;
        ctx->state[1] = 0xEFCDAB89;
        ctx->state[2] = 0x98BADCFE;
        ctx->state[3] = 0x10325476;
    }

    void Md5::md5_process(md5_context* ctx, uint8 data[64])
    {
        uint32 X[16], A, B, C, D;

        GET_UINT32(X[0], data, 0);
        GET_UINT32(X[1], data, 4);
        GET_UINT32(X[2], data, 8);
        GET_UINT32(X[3], data, 12);
        GET_UINT32(X[4], data, 16);
        GET_UINT32(X[5], data, 20);
        GET_UINT32(X[6], data, 24);
        GET_UINT32(X[7], data, 28);
        GET_UINT32(X[8], data, 32);
        GET_UINT32(X[9], data, 36);
        GET_UINT32(X[10], data, 40);
        GET_UINT32(X[11], data, 44);
        GET_UINT32(X[12], data, 48);
        GET_UINT32(X[13], data, 52);
        GET_UINT32(X[14], data, 56);
        GET_UINT32(X[15], data, 60);

#define S(x,n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))

#define P(a,b,c,d,k,s,t)                                \
{                                                       \
    a += F(b,c,d) + X[k] + t; a = S(a,s) + b;           \
}

        A = ctx->state[0];
        B = ctx->state[1];
        C = ctx->state[2];
        D = ctx->state[3];

#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

#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

#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

#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 F

        ctx->state[0] += A;
        ctx->state[1] += B;
        ctx->state[2] += C;
        ctx->state[3] += D;
    }

    void Md5::md5_update(md5_context* ctx, uint8* input, uint32 length)
    {
        uint32 left, fill;

        if (!length) return;

        left = ctx->total[0] & 0x3F;
        fill = 64 - left;

        ctx->total[0] += length;
        ctx->total[0] &= 0xFFFFFFFF;

        if (ctx->total[0] < length)
            ctx->total[1]++;

        if (left && length >= fill)
        {
            memcpy((void*)(ctx->buffer + left),
                (void*)input, fill);
            md5_process(ctx, ctx->buffer);
            length -= fill;
            input += fill;
            left = 0;
        }

        while (length >= 64)
        {
            md5_process(ctx, input);
            length -= 64;
            input += 64;
        }

        if (length)
        {
            memcpy((void*)(ctx->buffer + left),
                (void*)input, length);
        }
    }

    void Md5::md5_finish(md5_context* ctx, uint8 digest[16])
    {
        uint32 last, padn;
        uint32 high, low;
        uint8 msglen[8];

        high = (ctx->total[0] >> 29)
            | (ctx->total[1] << 3);
        low = (ctx->total[0] << 3);

        PUT_UINT32(low, msglen, 0);
        PUT_UINT32(high, msglen, 4);

        last = ctx->total[0] & 0x3F;
        padn = (last < 56) ? (56 - last) : (120 - last);

        md5_update(ctx, md5_padding, padn);
        md5_update(ctx, msglen, 8);

        PUT_UINT32(ctx->state[0], digest, 0);
        PUT_UINT32(ctx->state[1], digest, 4);
        PUT_UINT32(ctx->state[2], digest, 8);
        PUT_UINT32(ctx->state[3], digest, 12);
    }

    void Md5::Get(uint8* input, uint8 digest[MD5_DATA_LEN]) {
        Md5* p = new Md5();
        md5_context ctx;
        p->md5_starts(&ctx);
        p->md5_update(&ctx, input, strlen((const char*)input));
        p->md5_finish(&ctx, digest);
        delete p;
    }
}