// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: MIT-0

/*
* SHA1 hash algorithm. Used in SSH-2 as a MAC, and the transform is
* also used as a `stirring' function for the PuTTY random number
* pool. Implemented directly from the specification by Simon
* Tatham.
*/

#include "ssh.h"

/* ----------------------------------------------------------------------
* Core SHA algorithm: processes 16-word blocks into a message digest.
*/

#define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) )

static void SHA_Core_Init(uint32 h[5])
{
	h[0] = 0x67452301;
	h[1] = 0xefcdab89;
	h[2] = 0x98badcfe;
	h[3] = 0x10325476;
	h[4] = 0xc3d2e1f0;
}

void SHATransform(word32 * digest, word32 * block)
{
	word32 w[80];
	word32 a, b, c, d, e;
	int t;

#ifdef RANDOM_DIAGNOSTICS
	{
		extern int random_diagnostics;
		if (random_diagnostics) {
			int i;
			printf("SHATransform:");
			for (i = 0; i < 5; i++)
				printf(" %08x", digest[i]);
			printf(" +");
			for (i = 0; i < 16; i++)
				printf(" %08x", block[i]);
		}
	}
#endif

	for (t = 0; t < 16; t++)
		w[t] = block[t];

	for (t = 16; t < 80; t++) {
		word32 tmp = w[t - 3] ^ w[t - 8] ^ w[t - 14] ^ w[t - 16];
		w[t] = rol(tmp, 1);
	}

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

	for (t = 0; t < 20; t++) {
		word32 tmp =
			rol(a, 5) + ((b & c) | (d & ~b)) + e + w[t] + 0x5a827999;
		e = d;
		d = c;
		c = rol(b, 30);
		b = a;
		a = tmp;
	}
	for (t = 20; t < 40; t++) {
		word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0x6ed9eba1;
		e = d;
		d = c;
		c = rol(b, 30);
		b = a;
		a = tmp;
	}
	for (t = 40; t < 60; t++) {
		word32 tmp = rol(a,
			5) + ((b & c) | (b & d) | (c & d)) + e + w[t] +
			0x8f1bbcdc;
		e = d;
		d = c;
		c = rol(b, 30);
		b = a;
		a = tmp;
	}
	for (t = 60; t < 80; t++) {
		word32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0xca62c1d6;
		e = d;
		d = c;
		c = rol(b, 30);
		b = a;
		a = tmp;
	}

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

#ifdef RANDOM_DIAGNOSTICS
	{
		extern int random_diagnostics;
		if (random_diagnostics) {
			int i;
			printf(" =");
			for (i = 0; i < 5; i++)
				printf(" %08x", digest[i]);
			printf("\n");
		}
	}
#endif
}

/* ----------------------------------------------------------------------
* Outer SHA algorithm: take an arbitrary length byte string,
* convert it into 16-word blocks with the prescribed padding at
* the end, and pass those blocks to the core SHA algorithm.
*/

void SHA_Init(SHA_State * s)
{
	SHA_Core_Init(s->h);
	s->blkused = 0;
	s->lenhi = s->lenlo = 0;
}

void SHA_Bytes(SHA_State * s, const void *p, int len)
{
	const unsigned char *q = (const unsigned char *)p;
	uint32 wordblock[16];
	uint32 lenw = len;
	int i;

	/*
	* Update the length field.
	*/
	s->lenlo += lenw;
	s->lenhi += (s->lenlo < lenw);

	if (s->blkused && s->blkused + len < 64) {
		/*
		* Trivial case: just add to the block.
		*/
		memcpy(s->block + s->blkused, q, len);
		s->blkused += len;
	}
	else {
		/*
		* We must complete and process at least one block.
		*/
		while (s->blkused + len >= 64) {
			memcpy(s->block + s->blkused, q, 64 - s->blkused);
			q += 64 - s->blkused;
			len -= 64 - s->blkused;
			/* Now process the block. Gather bytes big-endian into words */
			for (i = 0; i < 16; i++) {
				wordblock[i] =
					(((uint32)s->block[i * 4 + 0]) << 24) |
					(((uint32)s->block[i * 4 + 1]) << 16) |
					(((uint32)s->block[i * 4 + 2]) << 8) |
					(((uint32)s->block[i * 4 + 3]) << 0);
			}
			SHATransform(s->h, wordblock);
			s->blkused = 0;
		}
		memcpy(s->block, q, len);
		s->blkused = len;
	}
}

void SHA_Final(SHA_State * s, unsigned char *output)
{
	int i;
	int pad;
	unsigned char c[64];
	uint32 lenhi, lenlo;

	if (s->blkused >= 56)
		pad = 56 + 64 - s->blkused;
	else
		pad = 56 - s->blkused;

	lenhi = (s->lenhi << 3) | (s->lenlo >> (32 - 3));
	lenlo = (s->lenlo << 3);

	memset(c, 0, pad);
	c[0] = 0x80;
	SHA_Bytes(s, &c, pad);

	c[0] = (lenhi >> 24) & 0xFF;
	c[1] = (lenhi >> 16) & 0xFF;
	c[2] = (lenhi >> 8) & 0xFF;
	c[3] = (lenhi >> 0) & 0xFF;
	c[4] = (lenlo >> 24) & 0xFF;
	c[5] = (lenlo >> 16) & 0xFF;
	c[6] = (lenlo >> 8) & 0xFF;
	c[7] = (lenlo >> 0) & 0xFF;

	SHA_Bytes(s, &c, 8);

	for (i = 0; i < 5; i++) {
		output[i * 4] = (s->h[i] >> 24) & 0xFF;
		output[i * 4 + 1] = (s->h[i] >> 16) & 0xFF;
		output[i * 4 + 2] = (s->h[i] >> 8) & 0xFF;
		output[i * 4 + 3] = (s->h[i]) & 0xFF;
	}
}

void SHA_Simple(const void *p, int len, unsigned char *output)
{
	SHA_State s;

	SHA_Init(&s);
	SHA_Bytes(&s, p, len);
	SHA_Final(&s, output);
	smemclr(&s, sizeof(s));
}

/*
* Thin abstraction for things where hashes are pluggable.
*/

static void *sha1_init(void)
{
	SHA_State *s;

	s = snew(SHA_State);
	SHA_Init(s);
	return s;
}

static void sha1_bytes(void *handle, void *p, int len)
{
	SHA_State *s = (SHA_State *)handle;

	SHA_Bytes(s, p, len);
}

static void sha1_final(void *handle, unsigned char *output)
{
	SHA_State *s = (SHA_State *)handle;

	SHA_Final(s, output);
	smemclr(s, sizeof(*s));
	sfree(s);
}

const struct ssh_hash ssh_sha1 = {
	sha1_init, sha1_bytes, sha1_final, 20, "SHA-1"
};

//269
static void sha1_key_internal(void *handle, unsigned char *key, int len)
{
	SHA_State *keys = (SHA_State *)handle;
	unsigned char foo[64];
	int i;

	memset(foo, 0x36, 64);
	for (i = 0; i < len && i < 64; i++)
		foo[i] ^= key[i];
	SHA_Init(&keys[0]);
	SHA_Bytes(&keys[0], foo, 64);

	memset(foo, 0x5C, 64);
	for (i = 0; i < len && i < 64; i++)
		foo[i] ^= key[i];
	SHA_Init(&keys[1]);
	SHA_Bytes(&keys[1], foo, 64);

	smemclr(foo, 64);		       /* burn the evidence */
}


//389
void hmac_sha1_simple(void *key, int keylen, void *data, int datalen,
	unsigned char *output) {
	SHA_State states[2];
	unsigned char intermediate[20];

	sha1_key_internal(states, (unsigned char *)key, keylen);
	SHA_Bytes(&states[0], data, datalen);
	SHA_Final(&states[0], intermediate);

	SHA_Bytes(&states[1], intermediate, 20);
	SHA_Final(&states[1], output);
}