/*
 *	Copyright (C) 2006-2009 Vincent Hanquez <tab@snarc.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; version 2.1 or version 3.0 only.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * SHA1 implementation as describe in wikipedia.
 */

#include <string.h>
#include <stdio.h>
#include "sha1.h"
#include "bitfn.h"

/**
 * sha1_init - Init SHA1 context
 */
void sha1_init(struct sha1_ctx *ctx)
{
	memset(ctx, 0, sizeof(*ctx));

	/* initialize H */
	ctx->h[0] = 0x67452301;
	ctx->h[1] = 0xEFCDAB89;
	ctx->h[2] = 0x98BADCFE;
	ctx->h[3] = 0x10325476;
	ctx->h[4] = 0xC3D2E1F0;
}

#define f1(x, y, z)   (z ^ (x & (y ^ z)))         /* x ? y : z */
#define f2(x, y, z)   (x ^ y ^ z)                 /* XOR */
#define f3(x, y, z)   ((x & y) + (z & (x ^ y)))   /* majority */
#define f4(x, y, z)   f2(x, y, z)

#define K1  0x5A827999L                 /* Rounds  0-19: sqrt(2) * 2^30 */
#define K2  0x6ED9EBA1L                 /* Rounds 20-39: sqrt(3) * 2^30 */
#define K3  0x8F1BBCDCL                 /* Rounds 40-59: sqrt(5) * 2^30 */
#define K4  0xCA62C1D6L                 /* Rounds 60-79: sqrt(10) * 2^30 */

#define R(a, b, c, d, e, f, k, w)  e += rol32(a, 5) + f(b, c, d) + k + w; \
                                   b = rol32(b, 30)

#define M(i)  (w[i & 0x0f] = rol32(w[i & 0x0f] ^ w[(i - 14) & 0x0f] \
              ^ w[(i - 8) & 0x0f] ^ w[(i - 3) & 0x0f], 1))

static inline void sha1_do_chunk(unsigned char W[], unsigned int h[])
{
	unsigned int a, b, c, d, e;
	unsigned int w[80];

	#define CPY(i)	w[i] = be32_to_cpu(((unsigned int *) W)[i])
	CPY(0); CPY(1); CPY(2); CPY(3); CPY(4); CPY(5); CPY(6); CPY(7);
	CPY(8); CPY(9); CPY(10); CPY(11); CPY(12); CPY(13); CPY(14); CPY(15);
	#undef CPY

	a = h[0];
	b = h[1];
	c = h[2];
	d = h[3];
	e = h[4];

	/* following unrolled from:
	 *	for (i = 0; i < 20; i++) {
	 *		t = f1(b, c, d) + K1 + rol32(a, 5) + e + M(i);
	 *		e = d; d = c; c = rol32(b, 30); b = a; a = t;
	 *	}
	 */
	R(a, b, c, d, e, f1, K1, w[0]);
	R(e, a, b, c, d, f1, K1, w[1]);
	R(d, e, a, b, c, f1, K1, w[2]);
	R(c, d, e, a, b, f1, K1, w[3]);
	R(b, c, d, e, a, f1, K1, w[4]);
	R(a, b, c, d, e, f1, K1, w[5]);
	R(e, a, b, c, d, f1, K1, w[6]);
	R(d, e, a, b, c, f1, K1, w[7]);
	R(c, d, e, a, b, f1, K1, w[8]);
	R(b, c, d, e, a, f1, K1, w[9]);
	R(a, b, c, d, e, f1, K1, w[10]);
	R(e, a, b, c, d, f1, K1, w[11]);
	R(d, e, a, b, c, f1, K1, w[12]);
	R(c, d, e, a, b, f1, K1, w[13]);
	R(b, c, d, e, a, f1, K1, w[14]);
	R(a, b, c, d, e, f1, K1, w[15]);
	R(e, a, b, c, d, f1, K1, M(16));
	R(d, e, a, b, c, f1, K1, M(17));
	R(c, d, e, a, b, f1, K1, M(18));
	R(b, c, d, e, a, f1, K1, M(19));

	/* following unrolled from:
	 *	for (i = 20; i < 40; i++) {
	 *		t = f2(b, c, d) + K2 + rol32(a, 5) + e + M(i);
	 *		e = d; d = c; c = rol32(b, 30); b = a; a = t;
	 *	}
	 */

	R(a, b, c, d, e, f2, K2, M(20));
	R(e, a, b, c, d, f2, K2, M(21));
	R(d, e, a, b, c, f2, K2, M(22));
	R(c, d, e, a, b, f2, K2, M(23));
	R(b, c, d, e, a, f2, K2, M(24));
	R(a, b, c, d, e, f2, K2, M(25));
	R(e, a, b, c, d, f2, K2, M(26));
	R(d, e, a, b, c, f2, K2, M(27));
	R(c, d, e, a, b, f2, K2, M(28));
	R(b, c, d, e, a, f2, K2, M(29));
	R(a, b, c, d, e, f2, K2, M(30));
	R(e, a, b, c, d, f2, K2, M(31));
	R(d, e, a, b, c, f2, K2, M(32));
	R(c, d, e, a, b, f2, K2, M(33));
	R(b, c, d, e, a, f2, K2, M(34));
	R(a, b, c, d, e, f2, K2, M(35));
	R(e, a, b, c, d, f2, K2, M(36));
	R(d, e, a, b, c, f2, K2, M(37));
	R(c, d, e, a, b, f2, K2, M(38));
	R(b, c, d, e, a, f2, K2, M(39));

	/* following unrolled from:
	 *	for (i = 40; i < 60; i++) {
	 *		t = f3(b, c, d) + K3 + rol32(a, 5) + e + M(i);
	 *		e = d; d = c; c = rol32(b, 30); b = a; a = t;
	 *	}
	 */

	R(a, b, c, d, e, f3, K3, M(40));
	R(e, a, b, c, d, f3, K3, M(41));
	R(d, e, a, b, c, f3, K3, M(42));
	R(c, d, e, a, b, f3, K3, M(43));
	R(b, c, d, e, a, f3, K3, M(44));
	R(a, b, c, d, e, f3, K3, M(45));
	R(e, a, b, c, d, f3, K3, M(46));
	R(d, e, a, b, c, f3, K3, M(47));
	R(c, d, e, a, b, f3, K3, M(48));
	R(b, c, d, e, a, f3, K3, M(49));
	R(a, b, c, d, e, f3, K3, M(50));
	R(e, a, b, c, d, f3, K3, M(51));
	R(d, e, a, b, c, f3, K3, M(52));
	R(c, d, e, a, b, f3, K3, M(53));
	R(b, c, d, e, a, f3, K3, M(54));
	R(a, b, c, d, e, f3, K3, M(55));
	R(e, a, b, c, d, f3, K3, M(56));
	R(d, e, a, b, c, f3, K3, M(57));
	R(c, d, e, a, b, f3, K3, M(58));
	R(b, c, d, e, a, f3, K3, M(59));

	/* following unrolled from:
	 *	for (i = 60; i < 80; i++) {
	 *		t = f2(b, c, d) + K4 + rol32(a, 5) + e + M(i);
	 *		e = d; d = c; c = rol32(b, 30); b = a; a = t;
	 *	}
	 */
	R(a, b, c, d, e, f4, K4, M(60));
	R(e, a, b, c, d, f4, K4, M(61));
	R(d, e, a, b, c, f4, K4, M(62));
	R(c, d, e, a, b, f4, K4, M(63));
	R(b, c, d, e, a, f4, K4, M(64));
	R(a, b, c, d, e, f4, K4, M(65));
	R(e, a, b, c, d, f4, K4, M(66));
	R(d, e, a, b, c, f4, K4, M(67));
	R(c, d, e, a, b, f4, K4, M(68));
	R(b, c, d, e, a, f4, K4, M(69));
	R(a, b, c, d, e, f4, K4, M(70));
	R(e, a, b, c, d, f4, K4, M(71));
	R(d, e, a, b, c, f4, K4, M(72));
	R(c, d, e, a, b, f4, K4, M(73));
	R(b, c, d, e, a, f4, K4, M(74));
	R(a, b, c, d, e, f4, K4, M(75));
	R(e, a, b, c, d, f4, K4, M(76));
	R(d, e, a, b, c, f4, K4, M(77));
	R(c, d, e, a, b, f4, K4, M(78));
	R(b, c, d, e, a, f4, K4, M(79));

	h[0] += a;
	h[1] += b;
	h[2] += c;
	h[3] += d;
	h[4] += e;
}

/**
 * sha1_update - Update the SHA1 context values with length bytes of data
 */
void sha1_update(struct sha1_ctx *ctx, unsigned char *data, int len)
{
	unsigned int index, to_fill;

	index = (unsigned int) (ctx->sz & 0x3f);
	to_fill = 64 - index;

	ctx->sz += len;

	/* process partial buffer if there's enough data to make a block */
	if (index && len >= to_fill) {
		memcpy(ctx->buf + index, data, to_fill);
		sha1_do_chunk(ctx->buf, ctx->h);
		len -= to_fill;
		data += to_fill;
		index = 0;
	}

	/* process as much 64-block as possible */
	for (; len >= 64; len -= 64, data += 64)
		sha1_do_chunk(data, ctx->h);

	/* append data into buf */
	if (len)
		memcpy(ctx->buf + index, data, len);
}

/**
 * sha1_finalize - Finalize the context and create the SHA1 digest
 */
void sha1_finalize(struct sha1_ctx *ctx, sha1_digest *out)
{
	static unsigned char padding[64] = { 0x80, };
	unsigned int bits[2];
	unsigned int index, padlen;

	/* add padding and update data with it */
	bits[0] = cpu_to_be32((unsigned int) (ctx->sz >> 29));
	bits[1] = cpu_to_be32((unsigned int) (ctx->sz << 3));

	/* pad out to 56 */
	index = (unsigned int) (ctx->sz & 0x3f);
	padlen = (index < 56) ? (56 - index) : ((64 + 56) - index);
	sha1_update(ctx, padding, padlen);

	/* append length */
	sha1_update(ctx, (unsigned char *) bits, sizeof(bits));

	/* output hash */
	out->digest[0] = cpu_to_be32(ctx->h[0]);
	out->digest[1] = cpu_to_be32(ctx->h[1]);
	out->digest[2] = cpu_to_be32(ctx->h[2]);
	out->digest[3] = cpu_to_be32(ctx->h[3]);
	out->digest[4] = cpu_to_be32(ctx->h[4]);
}

/**
 * sha1_to_hex - Transform the SHA1 digest into a binary data
 */
void sha1_to_bin(sha1_digest *digest, char *out)
{
	uint32_t *ptr = (uint32_t *) out;

	ptr[0] = cpu_to_be32(digest->digest[0]);
	ptr[1] = cpu_to_be32(digest->digest[1]);
	ptr[2] = cpu_to_be32(digest->digest[2]);
	ptr[3] = cpu_to_be32(digest->digest[3]);
	ptr[4] = cpu_to_be32(digest->digest[4]);
}

/**
 * sha1_to_hex - Transform the SHA1 digest into a readable data
 */
void sha1_to_hex(sha1_digest *digest, char *out)
{

	#define D(i) (cpu_to_be32(digest->digest[i]))
	snprintf(out, 41, "%08x%08x%08x%08x%08x",
		D(0), D(1), D(2), D(3), D(4));
	#undef D
}