/*
 * Copyright 2016-2017 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*
 * Derived from the BLAKE2 reference implementation written by Samuel Neves.
 * Copyright 2012, Samuel Neves <sneves@dei.uc.pt>
 * More information about the BLAKE2 hash function and its implementations
 * can be found at https://blake2.net.
 */

#include <assert.h>
#include <string.h>
#include <openssl/crypto.h>

#include "blake2_local.h"
#include "blake2_impl.h"

static const uint32_t blake2s_IV[8] =
{
    0x6A09E667U, 0xBB67AE85U, 0x3C6EF372U, 0xA54FF53AU,
    0x510E527FU, 0x9B05688CU, 0x1F83D9ABU, 0x5BE0CD19U
};

static const uint8_t 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 } ,
};

/* Set that it's the last block we'll compress */
static ossl_inline void blake2s_set_lastblock(BLAKE2S_CTX *S)
{
    S->f[0] = -1;
}

/* Initialize the hashing state. */
static ossl_inline void blake2s_init0(BLAKE2S_CTX *S)
{
    int i;

    memset(S, 0, sizeof(BLAKE2S_CTX));
    for (i = 0; i < 8; ++i) {
        S->h[i] = blake2s_IV[i];
    }
}

/* init2 xors IV with input parameter block */
static void blake2s_init_param(BLAKE2S_CTX *S, const BLAKE2S_PARAM *P)
{
    const uint8_t *p = (const uint8_t *)(P);
    size_t i;

    /* The param struct is carefully hand packed, and should be 32 bytes on
     * every platform. */
    assert(sizeof(BLAKE2S_PARAM) == 32);
    blake2s_init0(S);
    /* IV XOR ParamBlock */
    for (i = 0; i < 8; ++i) {
        S->h[i] ^= load32(&p[i*4]);
    }
}

/* Initialize the hashing context.  Always returns 1. */
int BLAKE2s_Init(BLAKE2S_CTX *c)
{
    BLAKE2S_PARAM P[1];

    P->digest_length = BLAKE2S_DIGEST_LENGTH;
    P->key_length    = 0;
    P->fanout        = 1;
    P->depth         = 1;
    store32(P->leaf_length, 0);
    store48(P->node_offset, 0);
    P->node_depth    = 0;
    P->inner_length  = 0;
    memset(P->salt,     0, sizeof(P->salt));
    memset(P->personal, 0, sizeof(P->personal));
    blake2s_init_param(c, P);
    return 1;
}

/* Permute the state while xoring in the block of data. */
static void blake2s_compress(BLAKE2S_CTX *S,
                            const uint8_t *blocks,
                            size_t len)
{
    uint32_t m[16];
    uint32_t v[16];
    size_t i;
    size_t increment;

    /*
     * There are two distinct usage vectors for this function:
     *
     * a) BLAKE2s_Update uses it to process complete blocks,
     *    possibly more than one at a time;
     *
     * b) BLAK2s_Final uses it to process last block, always
     *    single but possibly incomplete, in which case caller
     *    pads input with zeros.
     */
    assert(len < BLAKE2S_BLOCKBYTES || len % BLAKE2S_BLOCKBYTES == 0);

    /*
     * Since last block is always processed with separate call,
     * |len| not being multiple of complete blocks can be observed
     * only with |len| being less than BLAKE2S_BLOCKBYTES ("less"
     * including even zero), which is why following assignment doesn't
     * have to reside inside the main loop below.
     */
    increment = len < BLAKE2S_BLOCKBYTES ? len : BLAKE2S_BLOCKBYTES;

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

    do {
        for (i = 0; i < 16; ++i) {
            m[i] = load32(blocks + i * sizeof(m[i]));
        }

        /* blake2s_increment_counter */
        S->t[0] += increment;
        S->t[1] += (S->t[0] < increment);

        v[ 8] = blake2s_IV[0];
        v[ 9] = blake2s_IV[1];
        v[10] = blake2s_IV[2];
        v[11] = blake2s_IV[3];
        v[12] = S->t[0] ^ blake2s_IV[4];
        v[13] = S->t[1] ^ blake2s_IV[5];
        v[14] = S->f[0] ^ blake2s_IV[6];
        v[15] = S->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 = rotr32(d ^ a, 16); \
            c = c + d; \
            b = rotr32(b ^ c, 12); \
            a = a + b + m[blake2s_sigma[r][2*i+1]]; \
            d = rotr32(d ^ a, 8); \
            c = c + d; \
            b = rotr32(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)
#if defined(OPENSSL_SMALL_FOOTPRINT)
        /* almost 3x reduction on x86_64, 4.5x on ARMv8, 4x on ARMv4 */
        for (i = 0; i < 10; i++) {
            ROUND(i);
        }
#else
        ROUND(0);
        ROUND(1);
        ROUND(2);
        ROUND(3);
        ROUND(4);
        ROUND(5);
        ROUND(6);
        ROUND(7);
        ROUND(8);
        ROUND(9);
#endif

        for (i = 0; i < 8; ++i) {
            S->h[i] = v[i] ^= v[i + 8] ^ S->h[i];
        }
#undef G
#undef ROUND
        blocks += increment;
        len -= increment;
    } while (len);
}

/* Absorb the input data into the hash state.  Always returns 1. */
int BLAKE2s_Update(BLAKE2S_CTX *c, const void *data, size_t datalen)
{
    const uint8_t *in = data;
    size_t fill;

    /*
     * Intuitively one would expect intermediate buffer, c->buf, to
     * store incomplete blocks. But in this case we are interested to
     * temporarily stash even complete blocks, because last one in the
     * stream has to be treated in special way, and at this point we
     * don't know if last block in *this* call is last one "ever". This
     * is the reason for why |datalen| is compared as >, and not >=.
     */
    fill = sizeof(c->buf) - c->buflen;
    if (datalen > fill) {
        if (c->buflen) {
            memcpy(c->buf + c->buflen, in, fill); /* Fill buffer */
            blake2s_compress(c, c->buf, BLAKE2S_BLOCKBYTES);
            c->buflen = 0;
            in += fill;
            datalen -= fill;
        }
        if (datalen > BLAKE2S_BLOCKBYTES) {
            size_t stashlen = datalen % BLAKE2S_BLOCKBYTES;
            /*
             * If |datalen| is a multiple of the blocksize, stash
             * last complete block, it can be final one...
             */
            stashlen = stashlen ? stashlen : BLAKE2S_BLOCKBYTES;
            datalen -= stashlen;
            blake2s_compress(c, in, datalen);
            in += datalen;
            datalen = stashlen;
        }
    }

    assert(datalen <= BLAKE2S_BLOCKBYTES);

    memcpy(c->buf + c->buflen, in, datalen);
    c->buflen += datalen; /* Be lazy, do not compress */

    return 1;
}

/*
 * Calculate the final hash and save it in md.
 * Always returns 1.
 */
int BLAKE2s_Final(unsigned char *md, BLAKE2S_CTX *c)
{
    int i;

    blake2s_set_lastblock(c);
    /* Padding */
    memset(c->buf + c->buflen, 0, sizeof(c->buf) - c->buflen);
    blake2s_compress(c, c->buf, c->buflen);

    /* Output full hash to temp buffer */
    for (i = 0; i < 8; ++i) {
        store32(md + sizeof(c->h[i]) * i, c->h[i]);
    }

    OPENSSL_cleanse(c, sizeof(BLAKE2S_CTX));
    return 1;
}
