/*
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is SHA 180-1 Reference Implementation (Compact version)
 *
 * The Initial Developer of the Original Code is Paul Kocher of
 * Cryptography Research.  Portions created by Paul Kocher are
 * Copyright (C) 1995-9 by Cryptography Research, Inc.  All
 * Rights Reserved.
 *
 * Contributor(s):
 *
 *     Paul Kocher
 *
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License Version 2 or later (the
 * "GPL"), in which case the provisions of the GPL are applicable
 * instead of those above.  If you wish to allow use of your
 * version of this file only under the terms of the GPL and not to
 * allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by
 * the GPL.  If you do not delete the provisions above, a recipient
 * may use your version of this file under either the MPL or the
 * GPL.
 */

#include "sha1.h"

#define SHA_ROT(X, n) (((X) << (n)) | ((X) >> (32 - (n))))

static void shaHashBlock(SHA_CTX *ctx) {
	int t;
	unsigned int A, B, C, D, E, TEMP;

	for (t = 16; t <= 79; t++) {
		ctx->W[t] =
			SHA_ROT (ctx->W[t - 3] ^ ctx->W[t - 8] ^ ctx->W[t - 14] ^ ctx->W[t - 16], 1);
	}

	A = ctx->H[0];
	B = ctx->H[1];
	C = ctx->H[2];
	D = ctx->H[3];
	E = ctx->H[4];

	for (t = 0; t <= 19; t++) {
		TEMP = SHA_ROT (A, 5) + (((C ^ D) & B) ^ D) + E + ctx->W[t] + 0x5a827999;
		E = D; D = C; C = SHA_ROT (B, 30); B = A; A = TEMP;
	}
	for (t = 20; t <= 39; t++) {
		TEMP = SHA_ROT (A, 5) + (B ^ C ^ D) + E + ctx->W[t] + 0x6ed9eba1;
		E = D; D = C; C = SHA_ROT (B, 30); B = A; A = TEMP;
	}
	for (t = 40; t <= 59; t++) {
		TEMP = SHA_ROT (A, 5) + ((B & C) | (D & (B | C))) + E + ctx->W[t] + 0x8f1bbcdc;
		E = D; D = C; C = SHA_ROT (B, 30); B = A; A = TEMP;
	}
	for (t = 60; t <= 79; t++) {
		TEMP = SHA_ROT (A, 5) + (B ^ C ^ D) + E + ctx->W[t] + 0xca62c1d6;
		E = D; D = C; C = SHA_ROT (B, 30); B = A; A = TEMP;
	}

	ctx->H[0] += A;
	ctx->H[1] += B;
	ctx->H[2] += C;
	ctx->H[3] += D;
	ctx->H[4] += E;
}

void SHA1_Init(SHA_CTX *ctx) {
	int i;

	ctx->lenW = 0;
	ctx->sizeHi = ctx->sizeLo = 0;

	// Initialize H with the magic constants (see FIPS180 for constants)
	ctx->H[0] = 0x67452301;
	ctx->H[1] = 0xefcdab89;
	ctx->H[2] = 0x98badcfe;
	ctx->H[3] = 0x10325476;
	ctx->H[4] = 0xc3d2e1f0;

	for (i = 0; i < 80; i++) {
		ctx->W[i] = 0;
	}
}

void SHA1_Update(SHA_CTX *ctx, const void *_dataIn, int len) {
	const unsigned char *dataIn = _dataIn;
	int i;

	// Read the data into W and process blocks as they get full
	for (i = 0; i < len; i++) {
		ctx->W[ctx->lenW / 4] <<= 8;
		ctx->W[ctx->lenW / 4] |= (unsigned int) dataIn[i];
		if ((++ctx->lenW) % 64 == 0) {
			shaHashBlock (ctx);
			ctx->lenW = 0;
		}
		ctx->sizeLo += 8;
		ctx->sizeHi += (ctx->sizeLo < 8);
	}
}

void SHA1_Final(unsigned char hashout[20], SHA_CTX *ctx) {
	unsigned char pad0x80 = 0x80;
	unsigned char pad0x00 = 0x00;
	unsigned char padlen[8];
	int i;

	/* Pad with a binary 1 (e.g. 0x80), then zeroes, then length */
	padlen[0] = (unsigned char) ((ctx->sizeHi >> 24) & 255);
	padlen[1] = (unsigned char) ((ctx->sizeHi >> 16) & 255);
	padlen[2] = (unsigned char) ((ctx->sizeHi >> 8) & 255);
	padlen[3] = (unsigned char) ((ctx->sizeHi >> 0) & 255);
	padlen[4] = (unsigned char) ((ctx->sizeLo >> 24) & 255);
	padlen[5] = (unsigned char) ((ctx->sizeLo >> 16) & 255);
	padlen[6] = (unsigned char) ((ctx->sizeLo >> 8) & 255);
	padlen[7] = (unsigned char) ((ctx->sizeLo >> 0) & 255);

	SHA1_Update (ctx, &pad0x80, 1);
	while (ctx->lenW != 56) {
		SHA1_Update (ctx, &pad0x00, 1);
	}
	SHA1_Update (ctx, padlen, 8);

	/* Output hash */
	for (i = 0; i < 20; i++) {
		hashout[i] = (unsigned char) (ctx->H[i / 4] >> 24);
		ctx->H[i / 4] <<= 8;
	}

	/* Re-initialize the context (also zeroizes contents) */
	SHA1_Init (ctx);
}