/*	$OpenBSD: sha2.c,v 1.19 2021/03/12 10:22:46 jsg Exp $	*/

/*
 * FILE:	sha2.c
 * AUTHOR:	Aaron D. Gifford <me@aarongifford.com>
 * 
 * Copyright (c) 2000-2001, Aaron D. Gifford
 * 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 copyright holder nor the names of contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTOR(S) ``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 AUTHOR OR CONTRIBUTOR(S) 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.
 *
 * $From: sha2.c,v 1.1 2001/11/08 00:01:51 adg Exp adg $
 */

#include <string.h>
#include "sha2.h"

char *SHA256End(SHA2_CTX *ctx, char *buf);

/*** SHA-256/384/512 Machine Architecture Definitions *****************/
/*
 * BYTE_ORDER NOTE:
 *
 * Please make sure that your system defines BYTE_ORDER.  If your
 * architecture is little-endian, make sure it also defines
 * LITTLE_ENDIAN and that the two (BYTE_ORDER and LITTLE_ENDIAN) are
 * equivalent.
 *
 * If your system does not define the above, then you can do so by
 * hand like this:
 *
 *   #define LITTLE_ENDIAN 1234
 *   #define BIG_ENDIAN    4321
 *
 * And for little-endian machines, add:
 *
 *   #define BYTE_ORDER LITTLE_ENDIAN 
 *
 * Or for big-endian machines:
 *
 *   #define BYTE_ORDER BIG_ENDIAN
 *
 * The FreeBSD machine this was written on defines BYTE_ORDER
 * appropriately by including <sys/types.h> (which in turn includes
 * <machine/endian.h> where the appropriate definitions are actually
 * made).
 */
#if !defined(BYTE_ORDER) || (BYTE_ORDER != BIG_ENDIAN)
#error little-endian support was removed
#endif


/*** SHA-256 Various Length Definitions ***********************/
/* NOTE: Most of these are in sha2.h */
#define SHA256_SHORT_BLOCK_LENGTH	(SHA256_BLOCK_LENGTH - 8)

/*
 * Macro for incrementally adding the unsigned 32-bit integer n to the
 * unsigned 64-bit integer (represented using a two-element array of
 * 32-bit words):
 */
#define ADDINC64(w,n)	{ \
	(w)[0] += (u_int32_t)(n); \
	if ((w)[0] < (n)) { \
		(w)[1]++; \
	} \
}

/*** THE SIX LOGICAL FUNCTIONS ****************************************/
/*
 * Bit shifting and rotation (used by the six SHA-XYZ logical functions:
 *
 *   NOTE:  The naming of R and S appears backwards here (R is a SHIFT and
 *   S is a ROTATION) because the SHA-256/384/512 description document
 *   (see http://csrc.nist.gov/cryptval/shs/sha256-384-512.pdf) uses this
 *   same "backwards" definition.
 */
/* Shift-right (used in SHA-256: */
#define R(b,x) 		((x) >> (b))
/* 32-bit Rotate-right (used in SHA-256): */
#define S32(b,x)	(((x) >> (b)) | ((x) << (32 - (b))))

/* Two of six logical functions used in SHA-256: */
#define Ch(x,y,z)	(((x) & (y)) ^ ((~(x)) & (z)))
#define Maj(x,y,z)	(((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))

/* Four of six logical functions used in SHA-256: */
#define Sigma0_256(x)	(S32(2,  (x)) ^ S32(13, (x)) ^ S32(22, (x)))
#define Sigma1_256(x)	(S32(6,  (x)) ^ S32(11, (x)) ^ S32(25, (x)))
#define sigma0_256(x)	(S32(7,  (x)) ^ S32(18, (x)) ^ R(3 ,   (x)))
#define sigma1_256(x)	(S32(17, (x)) ^ S32(19, (x)) ^ R(10,   (x)))

/*** INTERNAL FUNCTION PROTOTYPES *************************************/
/* NOTE: These should not be accessed directly from outside this
 * library -- they are intended for private internal visibility/use
 * only.
 */
void SHA256Transform(u_int32_t *, const u_int8_t *);


/*** SHA-XYZ INITIAL HASH VALUES AND CONSTANTS ************************/
/* Hash constant words K for SHA-256: */
const static u_int32_t K256[64] = {
	0x428a2f98UL, 0x71374491UL, 0xb5c0fbcfUL, 0xe9b5dba5UL,
	0x3956c25bUL, 0x59f111f1UL, 0x923f82a4UL, 0xab1c5ed5UL,
	0xd807aa98UL, 0x12835b01UL, 0x243185beUL, 0x550c7dc3UL,
	0x72be5d74UL, 0x80deb1feUL, 0x9bdc06a7UL, 0xc19bf174UL,
	0xe49b69c1UL, 0xefbe4786UL, 0x0fc19dc6UL, 0x240ca1ccUL,
	0x2de92c6fUL, 0x4a7484aaUL, 0x5cb0a9dcUL, 0x76f988daUL,
	0x983e5152UL, 0xa831c66dUL, 0xb00327c8UL, 0xbf597fc7UL,
	0xc6e00bf3UL, 0xd5a79147UL, 0x06ca6351UL, 0x14292967UL,
	0x27b70a85UL, 0x2e1b2138UL, 0x4d2c6dfcUL, 0x53380d13UL,
	0x650a7354UL, 0x766a0abbUL, 0x81c2c92eUL, 0x92722c85UL,
	0xa2bfe8a1UL, 0xa81a664bUL, 0xc24b8b70UL, 0xc76c51a3UL,
	0xd192e819UL, 0xd6990624UL, 0xf40e3585UL, 0x106aa070UL,
	0x19a4c116UL, 0x1e376c08UL, 0x2748774cUL, 0x34b0bcb5UL,
	0x391c0cb3UL, 0x4ed8aa4aUL, 0x5b9cca4fUL, 0x682e6ff3UL,
	0x748f82eeUL, 0x78a5636fUL, 0x84c87814UL, 0x8cc70208UL,
	0x90befffaUL, 0xa4506cebUL, 0xbef9a3f7UL, 0xc67178f2UL
};

/* Initial hash value H for SHA-256: */
const static u_int32_t sha256_initial_hash_value[8] = {
	0x6a09e667UL,
	0xbb67ae85UL,
	0x3c6ef372UL,
	0xa54ff53aUL,
	0x510e527fUL,
	0x9b05688cUL,
	0x1f83d9abUL,
	0x5be0cd19UL
};


/*** SHA-256: *********************************************************/
void
SHA256Init(SHA2_CTX *context)
{
	memcpy(context->state.st32, sha256_initial_hash_value,
	    SHA256_DIGEST_LENGTH);
	memset(context->buffer, 0, SHA256_BLOCK_LENGTH);
	context->bitcount[0] = 0;
	context->bitcount[1] = 0;
}

void
SHA256Transform(u_int32_t *state, const u_int8_t *data)
{
	u_int32_t	a, b, c, d, e, f, g, h, s0, s1;
	u_int32_t	T1, T2, W256[16];
	int		j;

	/* Initialize registers with the prev. intermediate value */
	a = state[0];
	b = state[1];
	c = state[2];
	d = state[3];
	e = state[4];
	f = state[5];
	g = state[6];
	h = state[7];

	j = 0;
	do {
		W256[j] = (u_int32_t)data[3] | ((u_int32_t)data[2] << 8) |
		    ((u_int32_t)data[1] << 16) | ((u_int32_t)data[0] << 24);
		data += 4;
		/* Apply the SHA-256 compression function to update a..h */
		T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + W256[j];
		T2 = Sigma0_256(a) + Maj(a, b, c);
		h = g;
		g = f;
		f = e;
		e = d + T1;
		d = c;
		c = b;
		b = a;
		a = T1 + T2;

		j++;
	} while (j < 16);

	do {
		/* Part of the message block expansion: */
		s0 = W256[(j+1)&0x0f];
		s0 = sigma0_256(s0);
		s1 = W256[(j+14)&0x0f];	
		s1 = sigma1_256(s1);

		/* Apply the SHA-256 compression function to update a..h */
		T1 = h + Sigma1_256(e) + Ch(e, f, g) + K256[j] + 
		     (W256[j&0x0f] += s1 + W256[(j+9)&0x0f] + s0);
		T2 = Sigma0_256(a) + Maj(a, b, c);
		h = g;
		g = f;
		f = e;
		e = d + T1;
		d = c;
		c = b;
		b = a;
		a = T1 + T2;

		j++;
	} while (j < 64);

	/* Compute the current intermediate hash value */
	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
	state[4] += e;
	state[5] += f;
	state[6] += g;
	state[7] += h;

	/* Clean up */
	a = b = c = d = e = f = g = h = T1 = T2 = 0;
}

void
SHA256Update(SHA2_CTX *context, const void *dataptr, size_t len)
{
	const u_int8_t *data = dataptr;
	size_t	freespace, usedspace;

	/* Calling with no data is valid (we do nothing) */
	if (len == 0)
		return;

	usedspace = (context->bitcount[0] >> 3) % SHA256_BLOCK_LENGTH;
	if (usedspace > 0) {
		/* Calculate how much free space is available in the buffer */
		freespace = SHA256_BLOCK_LENGTH - usedspace;

		if (len >= freespace) {
			/* Fill the buffer completely and process it */
			memcpy(&context->buffer[usedspace], data, freespace);
			ADDINC64(context->bitcount, freespace << 3);
			len -= freespace;
			data += freespace;
			SHA256Transform(context->state.st32, context->buffer);
		} else {
			/* The buffer is not yet full */
			memcpy(&context->buffer[usedspace], data, len);
			ADDINC64(context->bitcount, len << 3);
			/* Clean up: */
			usedspace = freespace = 0;
			return;
		}
	}
	while (len >= SHA256_BLOCK_LENGTH) {
		/* Process as many complete blocks as we can */
		SHA256Transform(context->state.st32, data);
		ADDINC64(context->bitcount, SHA256_BLOCK_LENGTH << 3);
		len -= SHA256_BLOCK_LENGTH;
		data += SHA256_BLOCK_LENGTH;
	}
	if (len > 0) {
		/* There's left-overs, so save 'em */
		memcpy(context->buffer, data, len);
		ADDINC64(context->bitcount, len << 3);
	}
	/* Clean up: */
	usedspace = freespace = 0;
}

void
SHA256Final(u_int8_t digest[], SHA2_CTX *context)
{
	unsigned int	usedspace;

	usedspace = (context->bitcount[0] >> 3) % SHA256_BLOCK_LENGTH;
	if (usedspace > 0) {
		/* Begin padding with a 1 bit: */
		context->buffer[usedspace++] = 0x80;

		if (usedspace <= SHA256_SHORT_BLOCK_LENGTH) {
			/* Set-up for the last transform: */
			memset(&context->buffer[usedspace], 0,
			    SHA256_SHORT_BLOCK_LENGTH - usedspace);
		} else {
			if (usedspace < SHA256_BLOCK_LENGTH) {
				memset(&context->buffer[usedspace], 0,
				    SHA256_BLOCK_LENGTH - usedspace);
			}
			/* Do second-to-last transform: */
			SHA256Transform(context->state.st32, context->buffer);

			/* And set-up for the last transform: */
			memset(context->buffer, 0,
			    SHA256_SHORT_BLOCK_LENGTH);
		}
	} else {
		/* Set-up for the last transform: */
		memset(context->buffer, 0, SHA256_SHORT_BLOCK_LENGTH);

		/* Begin padding with a 1 bit: */
		*context->buffer = 0x80;
	}
	/* Set the bit count: */
	*(u_int32_t *)&context->buffer[SHA256_SHORT_BLOCK_LENGTH] = context->bitcount[1];
	*(u_int32_t *)&context->buffer[SHA256_SHORT_BLOCK_LENGTH + 4] = context->bitcount[0];

	/* Final transform: */
	SHA256Transform(context->state.st32, context->buffer);
	memcpy(digest, context->state.st32, SHA256_DIGEST_LENGTH);
	
	/* Clean up state data: */
	memset(context, 0, sizeof(*context));
	usedspace = 0;
}

char *
SHA256End(SHA2_CTX *ctx, char *buf)
{
	short i;
	u_int8_t digest[SHA256_DIGEST_LENGTH];
	static const char hex[] = "0123456789abcdef";
	
	if (buf == NULL)
		return NULL;

	SHA256Final(digest, ctx);
	for (i = 0; i < SHA256_DIGEST_LENGTH; i++) {
		buf[i + i] = hex[digest[i] >> 4];
		buf[i + i + 1] = hex[digest[i] & 0x0f];
	}
	buf[i + i] = '\0';
	memset(digest, 0, sizeof(digest));
	return (buf);
}

char *
SHA256Data(const u_int8_t *data, size_t len, char *buf)
{
	SHA2_CTX ctx;
	
	SHA256Init(&ctx);
	SHA256Update(&ctx, data, len);
	return SHA256End(&ctx, buf);
}