/* MIT License

 *

 * Copyright (c) 2016-2022 INRIA, CMU and Microsoft Corporation

 * Copyright (c) 2022-2023 HACL* Contributors

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in all

 * copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE.

 */

#include "internal/Hacl_Chacha20.h"

const uint32_t

    Hacl_Impl_Chacha20_Vec_chacha20_constants[4U] = { (uint32_t)0x61707865U, (uint32_t)0x3320646eU, (uint32_t)0x79622d32U, (uint32_t)0x6b206574U };

static inline void

quarter_round(uint32_t *st, uint32_t a, uint32_t b, uint32_t c, uint32_t d)

{

    uint32_t sta = st[a];

    uint32_t stb0 = st[b];

    uint32_t std0 = st[d];

    uint32_t sta10 = sta + stb0;

    uint32_t std10 = std0 ^ sta10;

    uint32_t std2 = std10 << (uint32_t)16U | std10 >> (uint32_t)16U;

    st[a] = sta10;

    st[d] = std2;

    uint32_t sta0 = st[c];

    uint32_t stb1 = st[d];

    uint32_t std3 = st[b];

    uint32_t sta11 = sta0 + stb1;

    uint32_t std11 = std3 ^ sta11;

    uint32_t std20 = std11 << (uint32_t)12U | std11 >> (uint32_t)20U;

    st[c] = sta11;

    st[b] = std20;

    uint32_t sta2 = st[a];

    uint32_t stb2 = st[b];

    uint32_t std4 = st[d];

    uint32_t sta12 = sta2 + stb2;

    uint32_t std12 = std4 ^ sta12;

    uint32_t std21 = std12 << (uint32_t)8U | std12 >> (uint32_t)24U;

    st[a] = sta12;

    st[d] = std21;

    uint32_t sta3 = st[c];

    uint32_t stb = st[d];

    uint32_t std = st[b];

    uint32_t sta1 = sta3 + stb;

    uint32_t std1 = std ^ sta1;

    uint32_t std22 = std1 << (uint32_t)7U | std1 >> (uint32_t)25U;

    st[c] = sta1;

    st[b] = std22;

}

static inline void

double_round(uint32_t *st)

{

    quarter_round(st, (uint32_t)0U, (uint32_t)4U, (uint32_t)8U, (uint32_t)12U);

    quarter_round(st, (uint32_t)1U, (uint32_t)5U, (uint32_t)9U, (uint32_t)13U);

    quarter_round(st, (uint32_t)2U, (uint32_t)6U, (uint32_t)10U, (uint32_t)14U);

    quarter_round(st, (uint32_t)3U, (uint32_t)7U, (uint32_t)11U, (uint32_t)15U);

    quarter_round(st, (uint32_t)0U, (uint32_t)5U, (uint32_t)10U, (uint32_t)15U);

    quarter_round(st, (uint32_t)1U, (uint32_t)6U, (uint32_t)11U, (uint32_t)12U);

    quarter_round(st, (uint32_t)2U, (uint32_t)7U, (uint32_t)8U, (uint32_t)13U);

    quarter_round(st, (uint32_t)3U, (uint32_t)4U, (uint32_t)9U, (uint32_t)14U);

}

static inline void

rounds(uint32_t *st)

{

    double_round(st);

    double_round(st);

    double_round(st);

    double_round(st);

    double_round(st);

    double_round(st);

    double_round(st);

    double_round(st);

    double_round(st);

    double_round(st);

}

static inline void

chacha20_core(uint32_t *k, uint32_t *ctx, uint32_t ctr)

{

    memcpy(k, ctx, (uint32_t)16U * sizeof(uint32_t));

    uint32_t ctr_u32 = ctr;

    k[12U] = k[12U] + ctr_u32;

    rounds(k);

    KRML_MAYBE_FOR16(i,

                     (uint32_t)0U,

                     (uint32_t)16U,

                     (uint32_t)1U,

                     uint32_t *os = k;

                     uint32_t x = k[i] + ctx[i];

                     os[i] = x;);

    k[12U] = k[12U] + ctr_u32;

}

static const uint32_t

    chacha20_constants[4U] = { (uint32_t)0x61707865U, (uint32_t)0x3320646eU, (uint32_t)0x79622d32U, (uint32_t)0x6b206574U };

void

Hacl_Impl_Chacha20_chacha20_init(uint32_t *ctx, uint8_t *k, uint8_t *n, uint32_t ctr)

{

    KRML_MAYBE_FOR4(i,

                    (uint32_t)0U,

                    (uint32_t)4U,

                    (uint32_t)1U,

                    uint32_t *os = ctx;

                    uint32_t x = chacha20_constants[i];

                    os[i] = x;);

    KRML_MAYBE_FOR8(i,

                    (uint32_t)0U,

                    (uint32_t)8U,

                    (uint32_t)1U,

                    uint32_t *os = ctx + (uint32_t)4U;

                    uint8_t *bj = k + i * (uint32_t)4U;

                    uint32_t u = load32_le(bj);

                    uint32_t r = u;

                    uint32_t x = r;

                    os[i] = x;);

    ctx[12U] = ctr;

    KRML_MAYBE_FOR3(i,

                    (uint32_t)0U,

                    (uint32_t)3U,

                    (uint32_t)1U,

                    uint32_t *os = ctx + (uint32_t)13U;

                    uint8_t *bj = n + i * (uint32_t)4U;

                    uint32_t u = load32_le(bj);

                    uint32_t r = u;

                    uint32_t x = r;

                    os[i] = x;);

}

static void

chacha20_encrypt_block(uint32_t *ctx, uint8_t *out, uint32_t incr, uint8_t *text)

{

    uint32_t k[16U] = { 0U };

    chacha20_core(k, ctx, incr);

    uint32_t bl[16U] = { 0U };

    KRML_MAYBE_FOR16(i,

                     (uint32_t)0U,

                     (uint32_t)16U,

                     (uint32_t)1U,

                     uint32_t *os = bl;

                     uint8_t *bj = text + i * (uint32_t)4U;

                     uint32_t u = load32_le(bj);

                     uint32_t r = u;

                     uint32_t x = r;

                     os[i] = x;);

    KRML_MAYBE_FOR16(i,

                     (uint32_t)0U,

                     (uint32_t)16U,

                     (uint32_t)1U,

                     uint32_t *os = bl;

                     uint32_t x = bl[i] ^ k[i];

                     os[i] = x;);

    KRML_MAYBE_FOR16(i,

                     (uint32_t)0U,

                     (uint32_t)16U,

                     (uint32_t)1U,

                     store32_le(out + i * (uint32_t)4U, bl[i]););

}

static inline void

chacha20_encrypt_last(uint32_t *ctx, uint32_t len, uint8_t *out, uint32_t incr, uint8_t *text)

{

    uint8_t plain[64U] = { 0U };

    memcpy(plain, text, len * sizeof(uint8_t));

    chacha20_encrypt_block(ctx, plain, incr, plain);

    memcpy(out, plain, len * sizeof(uint8_t));

}

void

Hacl_Impl_Chacha20_chacha20_update(uint32_t *ctx, uint32_t len, uint8_t *out, uint8_t *text)

{

    uint32_t rem = len % (uint32_t)64U;

    uint32_t nb = len / (uint32_t)64U;

    uint32_t rem1 = len % (uint32_t)64U;

    for (uint32_t i = (uint32_t)0U; i < nb; i++) {

        chacha20_encrypt_block(ctx, out + i * (uint32_t)64U, i, text + i * (uint32_t)64U);

    }

    if (rem1 > (uint32_t)0U) {

        chacha20_encrypt_last(ctx, rem, out + nb * (uint32_t)64U, nb, text + nb * (uint32_t)64U);

    }

}

void

Hacl_Chacha20_chacha20_encrypt(

    uint32_t len,

    uint8_t *out,

    uint8_t *text,

    uint8_t *key,

    uint8_t *n,

    uint32_t ctr)

{

    uint32_t ctx[16U] = { 0U };

    Hacl_Impl_Chacha20_chacha20_init(ctx, key, n, ctr);

    Hacl_Impl_Chacha20_chacha20_update(ctx, len, out, text);

}

void

Hacl_Chacha20_chacha20_decrypt(

    uint32_t len,

    uint8_t *out,

    uint8_t *cipher,

    uint8_t *key,

    uint8_t *n,

    uint32_t ctr)

{

    uint32_t ctx[16U] = { 0U };

    Hacl_Impl_Chacha20_chacha20_init(ctx, key, n, ctr);

    Hacl_Impl_Chacha20_chacha20_update(ctx, len, out, cipher);

}