/*
 * public domain blake2 implementation adapted from the reference
 * implementation by Samuel Neves
 * More information about the BLAKE2 hash function can be found at
 * https://blake2.net.
 */

#include <stdint.h>
#include <string.h>
#include <stdio.h>

#include "blake2.h"

static uint64_t load64(const void *src) {
#if defined(NATIVE_LITTLE_ENDIAN)
	uint64_t w;
	memcpy(&w, src, sizeof w);
	return w;
#else
	const uint8_t *p = (const uint8_t *) src;
	return ((uint64_t) (p[0]) << 0) |
	    ((uint64_t) (p[1]) << 8) |
	    ((uint64_t) (p[2]) << 16) |
	    ((uint64_t) (p[3]) << 24) |
	    ((uint64_t) (p[4]) << 32) |
	    ((uint64_t) (p[5]) << 40) |
	    ((uint64_t) (p[6]) << 48) | ((uint64_t) (p[7]) << 56);
#endif
}

static void store32(void *dst, uint32_t w) {
#if defined(NATIVE_LITTLE_ENDIAN)
	memcpy(dst, &w, sizeof w);
#else
	uint8_t *p = (uint8_t *) dst;
	p[0] = (uint8_t) (w >> 0);
	p[1] = (uint8_t) (w >> 8);
	p[2] = (uint8_t) (w >> 16);
	p[3] = (uint8_t) (w >> 24);
#endif
}

static void store64(void *dst, uint64_t w) {
#if defined(NATIVE_LITTLE_ENDIAN)
	memcpy(dst, &w, sizeof w);
#else
	uint8_t *p = (uint8_t *) dst;
	p[0] = (uint8_t) (w >> 0);
	p[1] = (uint8_t) (w >> 8);
	p[2] = (uint8_t) (w >> 16);
	p[3] = (uint8_t) (w >> 24);
	p[4] = (uint8_t) (w >> 32);
	p[5] = (uint8_t) (w >> 40);
	p[6] = (uint8_t) (w >> 48);
	p[7] = (uint8_t) (w >> 56);
#endif
}

static uint64_t rotr64(const uint64_t w, const unsigned c) {
	return (w >> c) | (w << (64 - c));
}

/* prevents compiler optimizing out memset() */
static void secure_zero_memory(void *v, size_t n) {
	static void *(*const volatile memset_v)(void *, int, size_t) =
	    &memset;
	memset_v(v, 0, n);
}

static const uint64_t blake2b_IV[8] = {
	0x6a09e667f3bcc908ULL, 0xbb67ae8584caa73bULL,
	0x3c6ef372fe94f82bULL, 0xa54ff53a5f1d36f1ULL,
	0x510e527fade682d1ULL, 0x9b05688c2b3e6c1fULL,
	0x1f83d9abfb41bd6bULL, 0x5be0cd19137e2179ULL
};

static const uint8_t blake2b_sigma[12][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 },
	{ 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 }
};


static void blake2b_set_lastnode(blake2b_state * S) {
	S->f[1] = (uint64_t) - 1;
}

/* Some helper functions, not necessarily useful */
static int blake2b_is_lastblock(const blake2b_state * S) {
	return S->f[0] != 0;
}

static void blake2b_set_lastblock(blake2b_state * S) {
	if (S->last_node)
		blake2b_set_lastnode(S);

	S->f[0] = (uint64_t) - 1;
}

static void blake2b_increment_counter(blake2b_state * S,
				      const uint64_t inc) {
	S->t[0] += inc;
	S->t[1] += (S->t[0] < inc);
}

static void blake2b_init0(blake2b_state * S) {
	size_t i;
	memset(S, 0, sizeof(blake2b_state));

	for (i = 0; i < 8; ++i)
		S->h[i] = blake2b_IV[i];
}

/* init xors IV with input parameter block */
int blake2b_init_param(blake2b_state * S, const blake2b_param * P) {
	const uint8_t *p = (const uint8_t *) (P);
	size_t i;

	blake2b_init0(S);

	/* IV XOR ParamBlock */
	for (i = 0; i < 8; ++i)
		S->h[i] ^= load64(p + sizeof(S->h[i]) * i);

	S->outlen = P->digest_length;
	return 0;
}

int blake2b_init(blake2b_state * S, size_t outlen) {
	blake2b_param P[1];

	if ((!outlen) || (outlen > BLAKE2B_OUTBYTES))
		return -1;

	P->digest_length = (uint8_t) outlen;
	P->key_length = 0;
	P->fanout = 1;
	P->depth = 1;
	store32(&P->leaf_length, 0);
	store32(&P->node_offset, 0);
	store32(&P->xof_length, 0);
	P->node_depth = 0;
	P->inner_length = 0;
	memset(P->reserved, 0, sizeof(P->reserved));
	memset(P->salt, 0, sizeof(P->salt));
	memset(P->personal, 0, sizeof(P->personal));
	return blake2b_init_param(S, P);
}

int blake2b_init_key(blake2b_state * S, size_t outlen, const void *key,
		     size_t keylen) {
	blake2b_param P[1];

	if ((!outlen) || (outlen > BLAKE2B_OUTBYTES))
		return -1;

	if (!key || !keylen || keylen > BLAKE2B_KEYBYTES)
		return -1;

	P->digest_length = (uint8_t) outlen;
	P->key_length = (uint8_t) keylen;
	P->fanout = 1;
	P->depth = 1;
	store32(&P->leaf_length, 0);
	store32(&P->node_offset, 0);
	store32(&P->xof_length, 0);
	P->node_depth = 0;
	P->inner_length = 0;
	memset(P->reserved, 0, sizeof(P->reserved));
	memset(P->salt, 0, sizeof(P->salt));
	memset(P->personal, 0, sizeof(P->personal));

	if (blake2b_init_param(S, P) < 0)
		return -1;

	{
		uint8_t block[BLAKE2B_BLOCKBYTES];
		memset(block, 0, BLAKE2B_BLOCKBYTES);
		memcpy(block, key, keylen);
		blake2b_update(S, block, BLAKE2B_BLOCKBYTES);
		secure_zero_memory(block, BLAKE2B_BLOCKBYTES);	/* Burn the key from stack */
	}
	return 0;
}

#define G(r,i,a,b,c,d)                      \
  do {                                      \
    a = a + b + m[blake2b_sigma[r][2*i+0]]; \
    d = rotr64(d ^ a, 32);                  \
    c = c + d;                              \
    b = rotr64(b ^ c, 24);                  \
    a = a + b + m[blake2b_sigma[r][2*i+1]]; \
    d = rotr64(d ^ a, 16);                  \
    c = c + d;                              \
    b = rotr64(b ^ c, 63);                  \
  } 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)

static void blake2b_compress(blake2b_state * S,
			     const uint8_t block[BLAKE2B_BLOCKBYTES]) {
	uint64_t m[16];
	uint64_t v[16];
	size_t i;

	for (i = 0; i < 16; ++i) {
		m[i] = load64(block + i * sizeof(m[i]));
	}

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

	v[8] = blake2b_IV[0];
	v[9] = blake2b_IV[1];
	v[10] = blake2b_IV[2];
	v[11] = blake2b_IV[3];
	v[12] = blake2b_IV[4] ^ S->t[0];
	v[13] = blake2b_IV[5] ^ S->t[1];
	v[14] = blake2b_IV[6] ^ S->f[0];
	v[15] = blake2b_IV[7] ^ S->f[1];

	ROUND(0);
	ROUND(1);
	ROUND(2);
	ROUND(3);
	ROUND(4);
	ROUND(5);
	ROUND(6);
	ROUND(7);
	ROUND(8);
	ROUND(9);
	ROUND(10);
	ROUND(11);

	for (i = 0; i < 8; ++i) {
		S->h[i] = S->h[i] ^ v[i] ^ v[i + 8];
	}
}

#undef G
#undef ROUND

int blake2b_update(blake2b_state * S, const void *pin, size_t inlen) {
	const unsigned char *in = (const unsigned char *) pin;
	if (inlen > 0) {
		size_t left = S->buflen;
		size_t fill = BLAKE2B_BLOCKBYTES - left;
		if (inlen > fill) {
			S->buflen = 0;
			memcpy(S->buf + left, in, fill);	/* Fill buffer */
			blake2b_increment_counter(S, BLAKE2B_BLOCKBYTES);
			blake2b_compress(S, S->buf);	/* Compress */
			in += fill;
			inlen -= fill;
			while (inlen > BLAKE2B_BLOCKBYTES) {
				blake2b_increment_counter(S,
							  BLAKE2B_BLOCKBYTES);
				blake2b_compress(S, in);
				in += BLAKE2B_BLOCKBYTES;
				inlen -= BLAKE2B_BLOCKBYTES;
			}
		}
		memcpy(S->buf + S->buflen, in, inlen);
		S->buflen += inlen;
	}
	return 0;
}

int blake2b_final(blake2b_state * S, void *out, size_t outlen) {
	uint8_t buffer[BLAKE2B_OUTBYTES] = { 0 };
	size_t i;

	if (out == NULL || outlen < S->outlen)
		return -1;

	if (blake2b_is_lastblock(S))
		return -1;

	blake2b_increment_counter(S, S->buflen);
	blake2b_set_lastblock(S);
	memset(S->buf + S->buflen, 0, BLAKE2B_BLOCKBYTES - S->buflen);	/* Padding */
	blake2b_compress(S, S->buf);

	for (i = 0; i < 8; ++i)	/* Output full hash to temp buffer */
		store64(buffer + sizeof(S->h[i]) * i, S->h[i]);

	memcpy(out, buffer, S->outlen);
	secure_zero_memory(buffer, sizeof(buffer));
	return 0;
}

/* inlen, at least, should be uint64_t. Others can be size_t. */
int blake2b(void *out, size_t outlen, const void *in, size_t inlen,
	    const void *key, size_t keylen) {
	blake2b_state S[1];

	/* Verify parameters */
	if (NULL == in && inlen > 0)
		return -1;

	if (NULL == out)
		return -1;

	if (NULL == key && keylen > 0)
		return -1;

	if (!outlen || outlen > BLAKE2B_OUTBYTES)
		return -1;

	if (keylen > BLAKE2B_KEYBYTES)
		return -1;

	if (keylen > 0) {
		if (blake2b_init_key(S, outlen, key, keylen) < 0)
			return -1;
	} else {
		if (blake2b_init(S, outlen) < 0)
			return -1;
	}

	blake2b_update(S, (const uint8_t *) in, inlen);
	blake2b_final(S, out, outlen);
	return 0;
}

int blake2(void *out, size_t outlen, const void *in, size_t inlen,
	   const void *key, size_t keylen) {
	return blake2b(out, outlen, in, inlen, key, keylen);
}