Mac.c

/* Copyright 2000, 2009, 2011, 2012 Neil Edelman, distributed under the terms
 of the GNU General Public License, see copying.txt */

/* AlexV hacked the game; thanks for the recomendations -- Jan 2011
I'm using Olivier Gay's SHA-256 implementation, slightly modified */

#include <string.h>
#include "Mac.h"

#define SHA256_BLOCK_SIZE  (512 / 8)

void hmac_sha256(unsigned char *key,
				 unsigned char *message, unsigned int message_len,
				 unsigned char *mac, unsigned mac_size);

char *Mac(const char *str) {
	static const char *mime = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
	static const char *key =
#ifdef SECRET
	SECRET
#else
	"5bdcc146bf60754e6a042426089575c75a003f089d2739839dec58b964ec3843"
#endif
	;
	int i;
	static char mac[SHA256_BLOCK_SIZE+1];

	hmac_sha256((unsigned char *)key, (unsigned char *)str, strlen(str), (unsigned char *)mac, SHA256_BLOCK_SIZE);

	/* URI stringise the MAC (loss of 2-bits) */
	for(i = 0; i < SHA256_BLOCK_SIZE; i++) mac[i] = mime[mac[i] & 63];
	mac[i] = '\0';

	return mac;
}

/*-
 * HMAC-SHA-224/256/384/512 implementation
 * Last update: 06/15/2005
 * Issue date:  06/15/2005
 *
 * Copyright (C) 2005 Olivier Gay <olivier.gay@a3.epfl.ch>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <stdint.h>

#define SHA256_DIGEST_SIZE ( 256 / 8)

#define SHFR(x, n)    (x >> n)
#define ROTR(x, n)   ((x >> n) | (x << ((sizeof(x) << 3) - n)))
#define CH(x, y, z)  ((x & y) ^ (~x & z))
#define MAJ(x, y, z) ((x & y) ^ (x & z) ^ (y & z))

#define SHA256_F1(x) (ROTR(x,  2) ^ ROTR(x, 13) ^ ROTR(x, 22))
#define SHA256_F2(x) (ROTR(x,  6) ^ ROTR(x, 11) ^ ROTR(x, 25))
#define SHA256_F3(x) (ROTR(x,  7) ^ ROTR(x, 18) ^ SHFR(x,  3))
#define SHA256_F4(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ SHFR(x, 10))

#define UNPACK32(x, str)                      \
{                                             \
	*((str) + 3) = (uint8) ((x)      );       \
	*((str) + 2) = (uint8) ((x) >>  8);       \
	*((str) + 1) = (uint8) ((x) >> 16);       \
	*((str) + 0) = (uint8) ((x) >> 24);       \
}

#define PACK32(str, x)                        \
{                                             \
	*(x) =   ((uint32) *((str) + 3)      )    \
	       | ((uint32) *((str) + 2) <<  8)    \
	       | ((uint32) *((str) + 1) << 16)    \
	       | ((uint32) *((str) + 0) << 24);   \
}

/* Macros used for loops unrolling */

#define SHA256_SCR(i)                         \
{                                             \
	w[i] =  SHA256_F4(w[i -  2]) + w[i -  7]  \
	      + SHA256_F3(w[i - 15]) + w[i - 16]; \
}

#define SHA256_EXP(a, b, c, d, e, f, g, h, j)               \
{                                                           \
	t1 = wv[h] + SHA256_F2(wv[e]) + CH(wv[e], wv[f], wv[g]) \
	     + sha256_k[j] + w[j];                              \
	t2 = SHA256_F1(wv[a]) + MAJ(wv[a], wv[b], wv[c]);       \
	wv[d] += t1;                                            \
	wv[h] = t1 + t2;                                        \
}

typedef uint8_t  uint8;
typedef uint32_t uint32;
typedef uint64_t uint64;

const static uint32 sha256_h0[8] = {
	0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
	0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};

uint32 sha256_k[64] = {
	0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
	0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
	0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
	0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
	0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
	0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
	0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
	0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
	0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
	0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
	0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
	0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
	0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
	0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
	0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
	0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};

/* sha2 */

typedef struct {
	unsigned int tot_len;
	unsigned int len;
	unsigned char block[2 * SHA256_BLOCK_SIZE];
	uint32 h[8];
} sha256_ctx;

void sha256_transf(sha256_ctx *ctx, const unsigned char *message,
                   unsigned int block_nb)
{
    uint32 w[64];
    uint32 wv[8];
    uint32 t1, t2;
    const unsigned char *sub_block;
    int i;
	
    for (i = 0; i < (int) block_nb; i++) {
        sub_block = message + (i << 6);
		
        PACK32(&sub_block[ 0], &w[ 0]); PACK32(&sub_block[ 4], &w[ 1]);
        PACK32(&sub_block[ 8], &w[ 2]); PACK32(&sub_block[12], &w[ 3]);
        PACK32(&sub_block[16], &w[ 4]); PACK32(&sub_block[20], &w[ 5]);
        PACK32(&sub_block[24], &w[ 6]); PACK32(&sub_block[28], &w[ 7]);
        PACK32(&sub_block[32], &w[ 8]); PACK32(&sub_block[36], &w[ 9]);
        PACK32(&sub_block[40], &w[10]); PACK32(&sub_block[44], &w[11]);
        PACK32(&sub_block[48], &w[12]); PACK32(&sub_block[52], &w[13]);
        PACK32(&sub_block[56], &w[14]); PACK32(&sub_block[60], &w[15]);
		
        SHA256_SCR(16); SHA256_SCR(17); SHA256_SCR(18); SHA256_SCR(19);
        SHA256_SCR(20); SHA256_SCR(21); SHA256_SCR(22); SHA256_SCR(23);
        SHA256_SCR(24); SHA256_SCR(25); SHA256_SCR(26); SHA256_SCR(27);
        SHA256_SCR(28); SHA256_SCR(29); SHA256_SCR(30); SHA256_SCR(31);
        SHA256_SCR(32); SHA256_SCR(33); SHA256_SCR(34); SHA256_SCR(35);
        SHA256_SCR(36); SHA256_SCR(37); SHA256_SCR(38); SHA256_SCR(39);
        SHA256_SCR(40); SHA256_SCR(41); SHA256_SCR(42); SHA256_SCR(43);
        SHA256_SCR(44); SHA256_SCR(45); SHA256_SCR(46); SHA256_SCR(47);
        SHA256_SCR(48); SHA256_SCR(49); SHA256_SCR(50); SHA256_SCR(51);
        SHA256_SCR(52); SHA256_SCR(53); SHA256_SCR(54); SHA256_SCR(55);
        SHA256_SCR(56); SHA256_SCR(57); SHA256_SCR(58); SHA256_SCR(59);
        SHA256_SCR(60); SHA256_SCR(61); SHA256_SCR(62); SHA256_SCR(63);
		
        wv[0] = ctx->h[0]; wv[1] = ctx->h[1];
        wv[2] = ctx->h[2]; wv[3] = ctx->h[3];
        wv[4] = ctx->h[4]; wv[5] = ctx->h[5];
        wv[6] = ctx->h[6]; wv[7] = ctx->h[7];
		
        SHA256_EXP(0,1,2,3,4,5,6,7, 0); SHA256_EXP(7,0,1,2,3,4,5,6, 1);
        SHA256_EXP(6,7,0,1,2,3,4,5, 2); SHA256_EXP(5,6,7,0,1,2,3,4, 3);
        SHA256_EXP(4,5,6,7,0,1,2,3, 4); SHA256_EXP(3,4,5,6,7,0,1,2, 5);
        SHA256_EXP(2,3,4,5,6,7,0,1, 6); SHA256_EXP(1,2,3,4,5,6,7,0, 7);
        SHA256_EXP(0,1,2,3,4,5,6,7, 8); SHA256_EXP(7,0,1,2,3,4,5,6, 9);
        SHA256_EXP(6,7,0,1,2,3,4,5,10); SHA256_EXP(5,6,7,0,1,2,3,4,11);
        SHA256_EXP(4,5,6,7,0,1,2,3,12); SHA256_EXP(3,4,5,6,7,0,1,2,13);
        SHA256_EXP(2,3,4,5,6,7,0,1,14); SHA256_EXP(1,2,3,4,5,6,7,0,15);
        SHA256_EXP(0,1,2,3,4,5,6,7,16); SHA256_EXP(7,0,1,2,3,4,5,6,17);
        SHA256_EXP(6,7,0,1,2,3,4,5,18); SHA256_EXP(5,6,7,0,1,2,3,4,19);
        SHA256_EXP(4,5,6,7,0,1,2,3,20); SHA256_EXP(3,4,5,6,7,0,1,2,21);
        SHA256_EXP(2,3,4,5,6,7,0,1,22); SHA256_EXP(1,2,3,4,5,6,7,0,23);
        SHA256_EXP(0,1,2,3,4,5,6,7,24); SHA256_EXP(7,0,1,2,3,4,5,6,25);
        SHA256_EXP(6,7,0,1,2,3,4,5,26); SHA256_EXP(5,6,7,0,1,2,3,4,27);
        SHA256_EXP(4,5,6,7,0,1,2,3,28); SHA256_EXP(3,4,5,6,7,0,1,2,29);
        SHA256_EXP(2,3,4,5,6,7,0,1,30); SHA256_EXP(1,2,3,4,5,6,7,0,31);
        SHA256_EXP(0,1,2,3,4,5,6,7,32); SHA256_EXP(7,0,1,2,3,4,5,6,33);
        SHA256_EXP(6,7,0,1,2,3,4,5,34); SHA256_EXP(5,6,7,0,1,2,3,4,35);
        SHA256_EXP(4,5,6,7,0,1,2,3,36); SHA256_EXP(3,4,5,6,7,0,1,2,37);
        SHA256_EXP(2,3,4,5,6,7,0,1,38); SHA256_EXP(1,2,3,4,5,6,7,0,39);
        SHA256_EXP(0,1,2,3,4,5,6,7,40); SHA256_EXP(7,0,1,2,3,4,5,6,41);
        SHA256_EXP(6,7,0,1,2,3,4,5,42); SHA256_EXP(5,6,7,0,1,2,3,4,43);
        SHA256_EXP(4,5,6,7,0,1,2,3,44); SHA256_EXP(3,4,5,6,7,0,1,2,45);
        SHA256_EXP(2,3,4,5,6,7,0,1,46); SHA256_EXP(1,2,3,4,5,6,7,0,47);
        SHA256_EXP(0,1,2,3,4,5,6,7,48); SHA256_EXP(7,0,1,2,3,4,5,6,49);
        SHA256_EXP(6,7,0,1,2,3,4,5,50); SHA256_EXP(5,6,7,0,1,2,3,4,51);
        SHA256_EXP(4,5,6,7,0,1,2,3,52); SHA256_EXP(3,4,5,6,7,0,1,2,53);
        SHA256_EXP(2,3,4,5,6,7,0,1,54); SHA256_EXP(1,2,3,4,5,6,7,0,55);
        SHA256_EXP(0,1,2,3,4,5,6,7,56); SHA256_EXP(7,0,1,2,3,4,5,6,57);
        SHA256_EXP(6,7,0,1,2,3,4,5,58); SHA256_EXP(5,6,7,0,1,2,3,4,59);
        SHA256_EXP(4,5,6,7,0,1,2,3,60); SHA256_EXP(3,4,5,6,7,0,1,2,61);
        SHA256_EXP(2,3,4,5,6,7,0,1,62); SHA256_EXP(1,2,3,4,5,6,7,0,63);
		
        ctx->h[0] += wv[0]; ctx->h[1] += wv[1];
        ctx->h[2] += wv[2]; ctx->h[3] += wv[3];
        ctx->h[4] += wv[4]; ctx->h[5] += wv[5];
        ctx->h[6] += wv[6]; ctx->h[7] += wv[7];
    }
}

void sha256_init(sha256_ctx *ctx)
{
    ctx->h[0] = sha256_h0[0]; ctx->h[1] = sha256_h0[1];
    ctx->h[2] = sha256_h0[2]; ctx->h[3] = sha256_h0[3];
    ctx->h[4] = sha256_h0[4]; ctx->h[5] = sha256_h0[5];
    ctx->h[6] = sha256_h0[6]; ctx->h[7] = sha256_h0[7];
    ctx->len = 0;
    ctx->tot_len = 0;
}

void sha256_update(sha256_ctx *ctx, const unsigned char *message,
                   unsigned int len)
{
    unsigned int block_nb;
    unsigned int new_len, rem_len, tmp_len;
    const unsigned char *shifted_message;
	
    tmp_len = SHA256_BLOCK_SIZE - ctx->len;
    rem_len = len < tmp_len ? len : tmp_len;
	
    memcpy(&ctx->block[ctx->len], message, rem_len);
	
    if (ctx->len + len < SHA256_BLOCK_SIZE) {
        ctx->len += len;
        return;
    }
	
    new_len = len - rem_len;
    block_nb = new_len / SHA256_BLOCK_SIZE;
	
    shifted_message = message + rem_len;
	
    sha256_transf(ctx, ctx->block, 1);
    sha256_transf(ctx, shifted_message, block_nb);
	
    rem_len = new_len % SHA256_BLOCK_SIZE;
	
    memcpy(ctx->block, &shifted_message[block_nb << 6],
           rem_len);
	
    ctx->len = rem_len;
    ctx->tot_len += (block_nb + 1) << 6;
}

void sha256_final(sha256_ctx *ctx, unsigned char *digest)
{
    unsigned int block_nb;
    unsigned int pm_len;
    unsigned int len_b;

    block_nb = (1 + ((SHA256_BLOCK_SIZE - 9)
                     < (ctx->len % SHA256_BLOCK_SIZE)));
	
    len_b = (ctx->tot_len + ctx->len) << 3;
    pm_len = block_nb << 6;
	
    memset(ctx->block + ctx->len, 0, pm_len - ctx->len);
    ctx->block[ctx->len] = 0x80;
    UNPACK32(len_b, ctx->block + pm_len - 4);
	
    sha256_transf(ctx, ctx->block, block_nb);
	
	UNPACK32(ctx->h[0], &digest[ 0]);
	UNPACK32(ctx->h[1], &digest[ 4]);
	UNPACK32(ctx->h[2], &digest[ 8]);
	UNPACK32(ctx->h[3], &digest[12]);
	UNPACK32(ctx->h[4], &digest[16]);
	UNPACK32(ctx->h[5], &digest[20]);
	UNPACK32(ctx->h[6], &digest[24]);
	UNPACK32(ctx->h[7], &digest[28]);
}

void sha256(const unsigned char *message, unsigned int len, unsigned char *digest)
{
    sha256_ctx ctx;
	
    sha256_init(&ctx);
    sha256_update(&ctx, message, len);
    sha256_final(&ctx, digest);
}

/* hmac-sha2 */

typedef struct {
    sha256_ctx ctx_inside;
    sha256_ctx ctx_outside;
	
    /* for hmac_reinit */
    sha256_ctx ctx_inside_reinit;
    sha256_ctx ctx_outside_reinit;
	
    unsigned char block_ipad[SHA256_BLOCK_SIZE];
    unsigned char block_opad[SHA256_BLOCK_SIZE];
} hmac_sha256_ctx;

void hmac_sha256_init(hmac_sha256_ctx *ctx, unsigned char *key)
{
    unsigned int num;
	
    unsigned char *key_used;
    int i;

	key_used = key;
	num = SHA256_BLOCK_SIZE;
	
    for (i = 0; i < num; i++) {
        ctx->block_ipad[i] = key_used[i] ^ 0x36;
        ctx->block_opad[i] = key_used[i] ^ 0x5c;
    }
	
    sha256_init(&ctx->ctx_inside);
    sha256_update(&ctx->ctx_inside, ctx->block_ipad, SHA256_BLOCK_SIZE);
	
    sha256_init(&ctx->ctx_outside);
    sha256_update(&ctx->ctx_outside, ctx->block_opad,
                  SHA256_BLOCK_SIZE);
	
    /* for hmac_reinit */
    memcpy(&ctx->ctx_inside_reinit, &ctx->ctx_inside,
           sizeof(sha256_ctx));
    memcpy(&ctx->ctx_outside_reinit, &ctx->ctx_outside,
           sizeof(sha256_ctx));
}

void hmac_sha256_reinit(hmac_sha256_ctx *ctx)
{
    memcpy(&ctx->ctx_inside, &ctx->ctx_inside_reinit,
           sizeof(sha256_ctx));
    memcpy(&ctx->ctx_outside, &ctx->ctx_outside_reinit,
           sizeof(sha256_ctx));
}

void hmac_sha256_update(hmac_sha256_ctx *ctx, unsigned char *message,
                        unsigned int message_len)
{
    sha256_update(&ctx->ctx_inside, message, message_len);
}

void hmac_sha256_final(hmac_sha256_ctx *ctx, unsigned char *mac,
                       unsigned int mac_size)
{
    unsigned char digest_inside[SHA256_DIGEST_SIZE];
    unsigned char mac_temp[SHA256_DIGEST_SIZE];
	
    sha256_final(&ctx->ctx_inside, digest_inside);
    sha256_update(&ctx->ctx_outside, digest_inside, SHA256_DIGEST_SIZE);
    sha256_final(&ctx->ctx_outside, mac_temp);
    memcpy(mac, mac_temp, mac_size);
}

void hmac_sha256(unsigned char *key,
				 unsigned char *message, unsigned int message_len,
				 unsigned char *mac, unsigned mac_size)
{
    hmac_sha256_ctx ctx;

    hmac_sha256_init(&ctx, key);
    hmac_sha256_update(&ctx, message, message_len);
    hmac_sha256_final(&ctx, mac, mac_size);
}