/* Original author: Samuel Neves <sneves@dei.uc.pt>
 *
 * Copyright (C) 2015-2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
 */

#include "blake2s.h"

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>

typedef struct {
	u8 digest_length;
	u8 key_length;
	u8 fanout;
	u8 depth;
	u32 leaf_length;
	u8 node_offset[6];
	u8 node_depth;
	u8 inner_length;
	u8 salt[8];
	u8 personal[8];
} __packed blake2s_param;

static const u32 blake2s_iv[8] = {
	0x6A09E667UL, 0xBB67AE85UL, 0x3C6EF372UL, 0xA54FF53AUL,
	0x510E527FUL, 0x9B05688CUL, 0x1F83D9ABUL, 0x5BE0CD19UL
};

static const u8 blake2s_sigma[10][16] = {
	{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
	{14, 10, 4, 8, 9, 15, 13, 6, 1, 12, 0, 2, 11, 7, 5, 3},
	{11, 8, 12, 0, 5, 2, 15, 13, 10, 14, 3, 6, 7, 1, 9, 4},
	{7, 9, 3, 1, 13, 12, 11, 14, 2, 6, 5, 10, 4, 0, 15, 8},
	{9, 0, 5, 7, 2, 4, 10, 15, 14, 1, 11, 12, 6, 8, 3, 13},
	{2, 12, 6, 10, 0, 11, 8, 3, 4, 13, 7, 5, 15, 14, 1, 9},
	{12, 5, 1, 15, 14, 13, 4, 10, 0, 7, 6, 3, 9, 2, 8, 11},
	{13, 11, 7, 14, 12, 1, 3, 9, 5, 0, 15, 4, 8, 6, 2, 10},
	{6, 15, 14, 9, 11, 3, 0, 8, 12, 2, 13, 7, 1, 4, 10, 5},
	{10, 2, 8, 4, 7, 6, 1, 5, 15, 11, 9, 14, 3, 12, 13, 0},
};

static inline u32 le32_to_cpuvp(const void *p)
{
	return le32_to_cpup(p);
}

static inline void blake2s_set_lastblock(struct blake2s_state *state)
{
	if (state->last_node)
		state->f[1] = -1;
	state->f[0] = -1;
}

static inline void blake2s_increment_counter(struct blake2s_state *state, const u32 inc)
{
	state->t[0] += inc;
	state->t[1] += (state->t[0] < inc);
}

/* init2 xors IV with input parameter block */
__attribute__((optimize("unroll-loops")))
static inline void blake2s_init_param(struct blake2s_state *state, const blake2s_param *param)
{
	const u32 *p;
	int i;
	memset(state, 0, sizeof(struct blake2s_state));
	for (i = 0; i < 8; ++i)
		state->h[i] = blake2s_iv[i];
	p = (const u32 *)param;
	/* IV XOR ParamBlock */
	for (i = 0; i < 8; ++i)
		state->h[i] ^= le32_to_cpuvp(&p[i]);
}

void blake2s_init(struct blake2s_state *state, const u8 outlen)
{
	blake2s_param param = {
		.digest_length = outlen,
		.fanout = 1,
		.depth = 1
	};

#ifdef DEBUG
	BUG_ON(!outlen || outlen > BLAKE2S_OUTBYTES);
#endif
	blake2s_init_param(state, &param);
}

void blake2s_init_key(struct blake2s_state *state, const u8 outlen, const void *key, const u8 keylen)
{
	blake2s_param param = {
		.digest_length = outlen,
		.key_length = keylen,
		.fanout = 1,
		.depth = 1
	};
	u8 block[BLAKE2S_BLOCKBYTES] = { 0 };

#ifdef DEBUG
	BUG_ON(!outlen || outlen > BLAKE2S_OUTBYTES || !key || !keylen || keylen > BLAKE2S_KEYBYTES);
#endif
	blake2s_init_param(state, &param);
	memcpy(block, key, keylen);
	blake2s_update(state, block, BLAKE2S_BLOCKBYTES);
	memzero_explicit(block, BLAKE2S_BLOCKBYTES);
}

__attribute__((optimize("unroll-loops")))
static inline void blake2s_compress(struct blake2s_state *state, const u8 block[BLAKE2S_BLOCKBYTES])
{
	u32 m[16];
	u32 v[16];
	int i;

	for (i = 0; i < 16; ++i)
		m[i] = le32_to_cpuvp(block + i * sizeof(m[i]));

	for (i = 0; i < 8; ++i)
		v[i] = state->h[i];

	v[8] = blake2s_iv[0];
	v[9] = blake2s_iv[1];
	v[10] = blake2s_iv[2];
	v[11] = blake2s_iv[3];
	v[12] = state->t[0] ^ blake2s_iv[4];
	v[13] = state->t[1] ^ blake2s_iv[5];
	v[14] = state->f[0] ^ blake2s_iv[6];
	v[15] = state->f[1] ^ blake2s_iv[7];
#define G(r,i,a,b,c,d) \
	do { \
		a = a + b + m[blake2s_sigma[r][2 * i + 0]]; \
		d = ror32(d ^ a, 16); \
		c = c + d; \
		b = ror32(b ^ c, 12); \
		a = a + b + m[blake2s_sigma[r][2 * i + 1]]; \
		d = ror32(d ^ a, 8); \
		c = c + d; \
		b = ror32(b ^ c, 7); \
	} while(0)
#define ROUND(r)  \
	do { \
	G(r,0,v[ 0],v[ 4],v[ 8],v[12]); \
	G(r,1,v[ 1],v[ 5],v[ 9],v[13]); \
	G(r,2,v[ 2],v[ 6],v[10],v[14]); \
	G(r,3,v[ 3],v[ 7],v[11],v[15]); \
	G(r,4,v[ 0],v[ 5],v[10],v[15]); \
	G(r,5,v[ 1],v[ 6],v[11],v[12]); \
	G(r,6,v[ 2],v[ 7],v[ 8],v[13]); \
	G(r,7,v[ 3],v[ 4],v[ 9],v[14]); \
} while(0)
	ROUND(0);
	ROUND(1);
	ROUND(2);
	ROUND(3);
	ROUND(4);
	ROUND(5);
	ROUND(6);
	ROUND(7);
	ROUND(8);
	ROUND(9);

	for (i = 0; i < 8; ++i)
		state->h[i] = state->h[i] ^ v[i] ^ v[i + 8];
#undef G
#undef ROUND
}

void blake2s_update(struct blake2s_state *state, const u8 *in, u64 inlen)
{
	size_t left, fill;
	while (inlen > 0) {
		left = state->buflen;
		fill = 2 * BLAKE2S_BLOCKBYTES - left;

		if (inlen > fill) {
			memcpy(state->buf + left, in, fill); // Fill buffer
			state->buflen += fill;
			blake2s_increment_counter(state, BLAKE2S_BLOCKBYTES);
			blake2s_compress(state, state->buf); // Compress
			memcpy(state->buf, state->buf + BLAKE2S_BLOCKBYTES, BLAKE2S_BLOCKBYTES);// Shift buffer left
			state->buflen -= BLAKE2S_BLOCKBYTES;
			in += fill;
			inlen -= fill;
		} else { // inlen <= fill
			memcpy(state->buf + left, in, inlen);
			state->buflen += inlen; // Be lazy, do not compress
			in += inlen;
			inlen -= inlen;
		}
	}
}

__attribute__((optimize("unroll-loops")))
void blake2s_final(struct blake2s_state *state, u8 *out, u8 outlen)
{
	u8 buffer[BLAKE2S_OUTBYTES] = { 0 };
	int i;

#ifdef DEBUG
	BUG_ON(!out || !outlen || outlen > BLAKE2S_OUTBYTES);
#endif

	if (state->buflen > BLAKE2S_BLOCKBYTES) {
		blake2s_increment_counter(state, BLAKE2S_BLOCKBYTES);
		blake2s_compress(state, state->buf);
		state->buflen -= BLAKE2S_BLOCKBYTES;
		memcpy(state->buf, state->buf + BLAKE2S_BLOCKBYTES, state->buflen);
	}

	blake2s_increment_counter(state, (u32) state->buflen);
	blake2s_set_lastblock(state);
	memset(state->buf + state->buflen, 0, 2 * BLAKE2S_BLOCKBYTES - state->buflen); /* Padding */
	blake2s_compress(state, state->buf);

	for (i = 0; i < 8; ++i) /* output full hash to temp buffer */
		*(__le32 *)(buffer + sizeof(state->h[i]) * i) = cpu_to_le32(state->h[i]);

	memcpy(out, buffer, outlen);

	/* Burn state from stack */
	memzero_explicit(buffer, BLAKE2S_OUTBYTES);
	memzero_explicit(state, sizeof(struct blake2s_state));
}

void blake2s(u8 *out, const u8 *in, const u8 *key, const u8 outlen, u64 inlen, const u8 keylen)
{
	struct blake2s_state state;

#ifdef DEBUG
	BUG_ON((!in && inlen > 0) || !out || !outlen || outlen > BLAKE2S_OUTBYTES || keylen > BLAKE2S_KEYBYTES);
#endif

	if (keylen > 0 && key)
		blake2s_init_key(&state, outlen, key, keylen);
	else
		blake2s_init(&state, outlen);

	blake2s_update(&state, in, inlen);
	blake2s_final(&state, out, outlen);
}

__attribute__((optimize("unroll-loops")))
void blake2s_hmac(u8 *out, const u8 *in, const u8 *key, const u8 outlen, const u64 inlen, const u64 keylen)
{
	struct blake2s_state state;
	u8 o_key[BLAKE2S_BLOCKBYTES] = { 0 };
	u8 i_key[BLAKE2S_BLOCKBYTES] = { 0 };
	u8 i_hash[BLAKE2S_OUTBYTES];
	int i;

	if (keylen > BLAKE2S_BLOCKBYTES) {
		blake2s_init(&state, BLAKE2S_OUTBYTES);
		blake2s_update(&state, key, keylen);
		blake2s_final(&state, o_key, BLAKE2S_OUTBYTES);
		memcpy(i_key, o_key, BLAKE2S_OUTBYTES);
	} else {
		memcpy(o_key, key, keylen);
		memcpy(i_key, key, keylen);
	}

	for (i = 0; i < BLAKE2S_BLOCKBYTES; ++i) {
		o_key[i] ^= 0x5c;
		i_key[i] ^= 0x36;
	}

	blake2s_init(&state, BLAKE2S_OUTBYTES);
	blake2s_update(&state, i_key, BLAKE2S_BLOCKBYTES);
	blake2s_update(&state, in, inlen);
	blake2s_final(&state, i_hash, BLAKE2S_OUTBYTES);

	blake2s_init(&state, BLAKE2S_OUTBYTES);
	blake2s_update(&state, o_key, BLAKE2S_BLOCKBYTES);
	blake2s_update(&state, i_hash, BLAKE2S_OUTBYTES);
	blake2s_final(&state, i_hash, BLAKE2S_OUTBYTES);

	memcpy(out, i_hash, outlen);
	memzero_explicit(o_key, BLAKE2S_BLOCKBYTES);
	memzero_explicit(i_key, BLAKE2S_BLOCKBYTES);
	memzero_explicit(i_hash, BLAKE2S_OUTBYTES);
}

#include "../selftest/blake2s.h"
