path: root/gost_grasshopper_cipher.c

/*
 * Maxim Tishkov 2016
 * This file is distributed under the same license as OpenSSL
 */

#include "gost_grasshopper_cipher.h"
#include "gost_grasshopper_defines.h"
#include "gost_grasshopper_math.h"
#include "gost_grasshopper_core.h"

#include <openssl/evp.h>
#include <openssl/rand.h>
#include <openssl/err.h>

#include <string.h>
#include <byteswap.h>

#include "gost_lcl.h"
#include "e_gost_err.h"

enum GRASSHOPPER_CIPHER_TYPE {
    GRASSHOPPER_CIPHER_ECB = 0,
    GRASSHOPPER_CIPHER_CBC,
    GRASSHOPPER_CIPHER_OFB,
    GRASSHOPPER_CIPHER_CFB,
    GRASSHOPPER_CIPHER_CTR,
    GRASSHOPPER_CIPHER_CTRACPKM,
    GRASSHOPPER_CIPHER_MGM,
};

static EVP_CIPHER *gost_grasshopper_ciphers[7] = {
    [GRASSHOPPER_CIPHER_ECB] = NULL,
    [GRASSHOPPER_CIPHER_CBC] = NULL,
    [GRASSHOPPER_CIPHER_OFB] = NULL,
    [GRASSHOPPER_CIPHER_CFB] = NULL,
    [GRASSHOPPER_CIPHER_CTR] = NULL,
    [GRASSHOPPER_CIPHER_CTRACPKM] = NULL,
    [GRASSHOPPER_CIPHER_MGM] = NULL,
};

static GRASSHOPPER_INLINE void
gost_grasshopper_cipher_destroy_ofb(gost_grasshopper_cipher_ctx * c);
static GRASSHOPPER_INLINE void
gost_grasshopper_cipher_destroy_ctr(gost_grasshopper_cipher_ctx * c);
static GRASSHOPPER_INLINE void
gost_grasshopper_cipher_destroy_mgm(gost_grasshopper_cipher_ctx * c);

struct GRASSHOPPER_CIPHER_PARAMS {
    int nid;
    grasshopper_init_cipher_func init_cipher;
    grasshopper_do_cipher_func do_cipher;
    grasshopper_destroy_cipher_func destroy_cipher;
    int block_size;
    int ctx_size;
    int iv_size;
    bool padding;
};

static struct GRASSHOPPER_CIPHER_PARAMS gost_cipher_params[7] = {
    [GRASSHOPPER_CIPHER_ECB] = {
                                NID_grasshopper_ecb,
                                gost_grasshopper_cipher_init_ecb,
                                gost_grasshopper_cipher_do_ecb,
                                NULL,
                                16,
                                sizeof(gost_grasshopper_cipher_ctx),
                                0,
                                true}
    ,
    [GRASSHOPPER_CIPHER_CBC] = {
                                NID_grasshopper_cbc,
                                gost_grasshopper_cipher_init_cbc,
                                gost_grasshopper_cipher_do_cbc,
                                NULL,
                                16,
                                sizeof(gost_grasshopper_cipher_ctx),
                                16,
                                true}
    ,
    [GRASSHOPPER_CIPHER_OFB] = {
                                NID_grasshopper_ofb,
                                gost_grasshopper_cipher_init_ofb,
                                gost_grasshopper_cipher_do_ofb,
                                gost_grasshopper_cipher_destroy_ofb,
                                1,
                                sizeof(gost_grasshopper_cipher_ctx_ofb),
                                16,
                                false}
    ,
    [GRASSHOPPER_CIPHER_CFB] = {
                                NID_grasshopper_cfb,
                                gost_grasshopper_cipher_init_cfb,
                                gost_grasshopper_cipher_do_cfb,
                                NULL,
                                1,
                                sizeof(gost_grasshopper_cipher_ctx),
                                16,
                                false}
    ,
    [GRASSHOPPER_CIPHER_CTR] = {
                                NID_grasshopper_ctr,
                                gost_grasshopper_cipher_init_ctr,
                                gost_grasshopper_cipher_do_ctr,
                                gost_grasshopper_cipher_destroy_ctr,
                                1,
                                sizeof(gost_grasshopper_cipher_ctx_ctr),
                                /* IV size is set to match full block, to make it responsibility of
                                 * user to assign correct values (IV || 0), and to make naive context
                                 * copy possible (for software such as openssh) */
                                16,
                                false}
    ,
    [GRASSHOPPER_CIPHER_CTRACPKM] = {
                                     NID_id_tc26_cipher_gostr3412_2015_kuznyechik_ctracpkm,
                                     gost_grasshopper_cipher_init_ctracpkm,
                                     gost_grasshopper_cipher_do_ctracpkm,
                                     gost_grasshopper_cipher_destroy_ctr,
                                     1,
                                     sizeof(gost_grasshopper_cipher_ctx_ctr),
                                     16,
                                     false}
    ,
#ifdef NID_kuznyechik_mgm
    [GRASSHOPPER_CIPHER_MGM] = {
                                NID_kuznyechik_mgm,
                                gost_grasshopper_cipher_init_mgm,
                                gost_grasshopper_cipher_do_mgm,
                                gost_grasshopper_cipher_destroy_mgm,
                                1,
                                sizeof(gost_grasshopper_cipher_ctx_mgm),
                                16,
                                false}
    ,
#else
    [GRASSHOPPER_CIPHER_MGM] = {
                                NID_undef,
                                NULL,
                                NULL,
                                NULL,
                                0,
                                0,
                                0,
                                false}
    ,
#endif
};

/* first 256 bit of D from draft-irtf-cfrg-re-keying-12 */
static const unsigned char ACPKM_D_2018[] = {
    0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, /*  64 bit */
    0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f, /* 128 bit */
    0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
    0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, /* 256 bit */
};

static void acpkm_next(gost_grasshopper_cipher_ctx * c)
{
    unsigned char newkey[GRASSHOPPER_KEY_SIZE];
    const int J = GRASSHOPPER_KEY_SIZE / GRASSHOPPER_BLOCK_SIZE;
    int n;

    for (n = 0; n < J; n++) {
        const unsigned char *D_n = &ACPKM_D_2018[n * GRASSHOPPER_BLOCK_SIZE];

        grasshopper_encrypt_block(&c->encrypt_round_keys,
                                  (grasshopper_w128_t *) D_n,
                                  (grasshopper_w128_t *) & newkey[n *
                                                                  GRASSHOPPER_BLOCK_SIZE],
                                  &c->buffer);
    }
    gost_grasshopper_cipher_key(c, newkey);
}

/* Set 256 bit  key into context */
GRASSHOPPER_INLINE void
gost_grasshopper_cipher_key(gost_grasshopper_cipher_ctx * c, const uint8_t *k)
{
    int i;
    for (i = 0; i < 2; i++) {
        grasshopper_copy128(&c->key.k.k[i],
                            (const grasshopper_w128_t *)(k + i * 16));
    }

    grasshopper_set_encrypt_key(&c->encrypt_round_keys, &c->key);
    grasshopper_set_decrypt_key(&c->decrypt_round_keys, &c->key);
}

/* Set master 256-bit key to be used in TLSTREE calculation into context */
GRASSHOPPER_INLINE void
gost_grasshopper_master_key(gost_grasshopper_cipher_ctx * c, const uint8_t *k)
{
    int i;
    for (i = 0; i < 2; i++) {
        grasshopper_copy128(&c->master_key.k.k[i],
                            (const grasshopper_w128_t *)(k + i * 16));
    }
}

/* Cleans up key from context */
GRASSHOPPER_INLINE void
gost_grasshopper_cipher_destroy(gost_grasshopper_cipher_ctx * c)
{
    int i;
    for (i = 0; i < 2; i++) {
        grasshopper_zero128(&c->key.k.k[i]);
        grasshopper_zero128(&c->master_key.k.k[i]);
    }
    for (i = 0; i < GRASSHOPPER_ROUND_KEYS_COUNT; i++) {
        grasshopper_zero128(&c->encrypt_round_keys.k[i]);
    }
    for (i = 0; i < GRASSHOPPER_ROUND_KEYS_COUNT; i++) {
        grasshopper_zero128(&c->decrypt_round_keys.k[i]);
    }
    grasshopper_zero128(&c->buffer);
}

static GRASSHOPPER_INLINE void
gost_grasshopper_cipher_destroy_ofb(gost_grasshopper_cipher_ctx * c)
{
    gost_grasshopper_cipher_ctx_ofb *ctx =
        (gost_grasshopper_cipher_ctx_ofb *) c;

    grasshopper_zero128(&ctx->buffer1);
}

static GRASSHOPPER_INLINE void
gost_grasshopper_cipher_destroy_ctr(gost_grasshopper_cipher_ctx * c)
{
    gost_grasshopper_cipher_ctx_ctr *ctx =
        (gost_grasshopper_cipher_ctx_ctr *) c;

    grasshopper_zero128(&ctx->partial_buffer);
}

static GRASSHOPPER_INLINE void
gost_grasshopper_cipher_destroy_mgm(gost_grasshopper_cipher_ctx * c)
{
    gost_grasshopper_cipher_ctx_mgm *ctx =
        (gost_grasshopper_cipher_ctx_mgm *) c;

    grasshopper_zero128(&ctx->partial_buffer);
}

int gost_grasshopper_cipher_init(EVP_CIPHER_CTX *ctx,
                                 const unsigned char *key,
                                 const unsigned char *iv, int enc)
{
    gost_grasshopper_cipher_ctx *c = EVP_CIPHER_CTX_get_cipher_data(ctx);

    if (EVP_CIPHER_CTX_get_app_data(ctx) == NULL) {
        EVP_CIPHER_CTX_set_app_data(ctx, EVP_CIPHER_CTX_get_cipher_data(ctx));
    }

    if (key != NULL) {
        gost_grasshopper_cipher_key(c, key);
        gost_grasshopper_master_key(c, key);
    }

    if (iv != NULL) {
        if (c->type == GRASSHOPPER_CIPHER_MGM) {
            gost_grasshopper_cipher_ctx_mgm *m =
                (gost_grasshopper_cipher_ctx_mgm *) c;

            /* 1st bit should be 0 */
            if (iv[0] > 127) {
                GOSTerr(GOST_F_GOST_GRASSHOPPER_CIPHER_INIT,
                        GOST_R_INVALID_IV_LENGTH);
                return 0;
            }
            memcpy(m->mgm_iv, iv, 16);
            *(unsigned char *)(m->mgm_iv) += 128;
        }
        memcpy((unsigned char *)EVP_CIPHER_CTX_original_iv(ctx), iv,
               EVP_CIPHER_CTX_iv_length(ctx));
    }

    memcpy(EVP_CIPHER_CTX_iv_noconst(ctx),
           EVP_CIPHER_CTX_original_iv(ctx), EVP_CIPHER_CTX_iv_length(ctx));

    grasshopper_zero128(&c->buffer);

    return 1;
}

GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_ecb(EVP_CIPHER_CTX *ctx, const unsigned char
                                                        *key, const unsigned char
                                                        *iv, int enc)
{
    gost_grasshopper_cipher_ctx *c = EVP_CIPHER_CTX_get_cipher_data(ctx);
    c->type = GRASSHOPPER_CIPHER_ECB;
    return gost_grasshopper_cipher_init(ctx, key, iv, enc);
}

GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_cbc(EVP_CIPHER_CTX *ctx, const unsigned char
                                                        *key, const unsigned char
                                                        *iv, int enc)
{
    gost_grasshopper_cipher_ctx *c = EVP_CIPHER_CTX_get_cipher_data(ctx);
    c->type = GRASSHOPPER_CIPHER_CBC;
    return gost_grasshopper_cipher_init(ctx, key, iv, enc);
}

GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_ofb(EVP_CIPHER_CTX *ctx, const unsigned char
                                                        *key, const unsigned char
                                                        *iv, int enc)
{
    gost_grasshopper_cipher_ctx_ofb *c = EVP_CIPHER_CTX_get_cipher_data(ctx);

    c->c.type = GRASSHOPPER_CIPHER_OFB;

    grasshopper_zero128(&c->buffer1);

    return gost_grasshopper_cipher_init(ctx, key, iv, enc);
}

GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_cfb(EVP_CIPHER_CTX *ctx, const unsigned char
                                                        *key, const unsigned char
                                                        *iv, int enc)
{
    gost_grasshopper_cipher_ctx *c = EVP_CIPHER_CTX_get_cipher_data(ctx);
    c->type = GRASSHOPPER_CIPHER_CFB;
    return gost_grasshopper_cipher_init(ctx, key, iv, enc);
}

GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_ctr(EVP_CIPHER_CTX *ctx, const unsigned char
                                                        *key, const unsigned char
                                                        *iv, int enc)
{
    gost_grasshopper_cipher_ctx_ctr *c = EVP_CIPHER_CTX_get_cipher_data(ctx);

    c->c.type = GRASSHOPPER_CIPHER_CTR;
    EVP_CIPHER_CTX_set_num(ctx, 0);

    grasshopper_zero128(&c->partial_buffer);

    return gost_grasshopper_cipher_init(ctx, key, iv, enc);
}

GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_ctracpkm(EVP_CIPHER_CTX
                                                             *ctx, const unsigned
                                                             char *key, const unsigned
                                                             char *iv, int enc)
{
    gost_grasshopper_cipher_ctx_ctr *c = EVP_CIPHER_CTX_get_cipher_data(ctx);

    /* NB: setting type makes EVP do_cipher callback useless */
    c->c.type = GRASSHOPPER_CIPHER_CTRACPKM;
    EVP_CIPHER_CTX_set_num(ctx, 0);
    c->section_size = 4096;

    return gost_grasshopper_cipher_init(ctx, key, iv, enc);
}

GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_mgm(EVP_CIPHER_CTX *ctx, const unsigned char
                                                        *key, const unsigned char
                                                        *iv, int enc)
{
    gost_grasshopper_cipher_ctx_mgm *c = EVP_CIPHER_CTX_get_cipher_data(ctx);

    c->c.type = GRASSHOPPER_CIPHER_MGM;
    c->taglen = 16;
    EVP_CIPHER_CTX_set_num(ctx, 0);

    grasshopper_zero128(&c->partial_buffer);

    return gost_grasshopper_cipher_init(ctx, key, iv, enc);
}

GRASSHOPPER_INLINE int gost_grasshopper_cipher_do(EVP_CIPHER_CTX *ctx,
                                                  unsigned char *out,
                                                  const unsigned char *in,
                                                  size_t inl)
{
    gost_grasshopper_cipher_ctx *c =
        (gost_grasshopper_cipher_ctx *) EVP_CIPHER_CTX_get_cipher_data(ctx);
    struct GRASSHOPPER_CIPHER_PARAMS *params = &gost_cipher_params[c->type];

    return params->do_cipher(ctx, out, in, inl);
}

int gost_grasshopper_cipher_do_ecb(EVP_CIPHER_CTX *ctx, unsigned char *out,
                                   const unsigned char *in, size_t inl)
{
    gost_grasshopper_cipher_ctx *c =
        (gost_grasshopper_cipher_ctx *) EVP_CIPHER_CTX_get_cipher_data(ctx);
    bool encrypting = (bool) EVP_CIPHER_CTX_encrypting(ctx);
    const unsigned char *current_in = in;
    unsigned char *current_out = out;
    size_t blocks = inl / GRASSHOPPER_BLOCK_SIZE;
    size_t i;

    for (i = 0; i < blocks;
         i++, current_in += GRASSHOPPER_BLOCK_SIZE, current_out +=
         GRASSHOPPER_BLOCK_SIZE) {
        if (encrypting) {
            grasshopper_encrypt_block(&c->encrypt_round_keys,
                                      (grasshopper_w128_t *) current_in,
                                      (grasshopper_w128_t *) current_out,
                                      &c->buffer);
        } else {
            grasshopper_decrypt_block(&c->decrypt_round_keys,
                                      (grasshopper_w128_t *) current_in,
                                      (grasshopper_w128_t *) current_out,
                                      &c->buffer);
        }
    }

    return 1;
}

int gost_grasshopper_cipher_do_cbc(EVP_CIPHER_CTX *ctx, unsigned char *out,
                                   const unsigned char *in, size_t inl)
{
    gost_grasshopper_cipher_ctx *c =
        (gost_grasshopper_cipher_ctx *) EVP_CIPHER_CTX_get_cipher_data(ctx);
    unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
    bool encrypting = (bool) EVP_CIPHER_CTX_encrypting(ctx);
    const unsigned char *current_in = in;
    unsigned char *current_out = out;
    grasshopper_w128_t *currentInputBlock;
    grasshopper_w128_t *currentOutputBlock;
    size_t blocks = inl / GRASSHOPPER_BLOCK_SIZE;
    size_t i;
    grasshopper_w128_t *currentBlock;

    currentBlock = (grasshopper_w128_t *) iv;

    for (i = 0; i < blocks;
         i++, current_in += GRASSHOPPER_BLOCK_SIZE, current_out +=
         GRASSHOPPER_BLOCK_SIZE) {
        currentInputBlock = (grasshopper_w128_t *) current_in;
        currentOutputBlock = (grasshopper_w128_t *) current_out;
        if (encrypting) {
            grasshopper_append128(currentBlock, currentInputBlock);
            grasshopper_encrypt_block(&c->encrypt_round_keys, currentBlock,
                                      currentOutputBlock, &c->buffer);
            grasshopper_copy128(currentBlock, currentOutputBlock);
        } else {
            grasshopper_w128_t tmp;

            grasshopper_copy128(&tmp, currentInputBlock);
            grasshopper_decrypt_block(&c->decrypt_round_keys,
                                      currentInputBlock, currentOutputBlock,
                                      &c->buffer);
            grasshopper_append128(currentOutputBlock, currentBlock);
            grasshopper_copy128(currentBlock, &tmp);
        }
    }

    return 1;
}

void inc_counter(unsigned char *counter, size_t counter_bytes)
{
    unsigned char c;
    unsigned int n = counter_bytes;

    do {
        --n;
        c = counter[n];
        ++c;
        counter[n] = c;
        if (c)
            return;
    } while (n);
}

/* increment counter (128-bit int) by 1 */
static void ctr128_inc(unsigned char *counter)
{
    inc_counter(counter, 16);
}

int gost_grasshopper_cipher_do_ctr(EVP_CIPHER_CTX *ctx, unsigned char *out,
                                   const unsigned char *in, size_t inl)
{
    gost_grasshopper_cipher_ctx_ctr *c = (gost_grasshopper_cipher_ctx_ctr *)
        EVP_CIPHER_CTX_get_cipher_data(ctx);
    unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
    const unsigned char *current_in = in;
    unsigned char *current_out = out;
    grasshopper_w128_t *currentInputBlock;
    grasshopper_w128_t *currentOutputBlock;
    unsigned int n = EVP_CIPHER_CTX_num(ctx);
    size_t lasted;
    size_t i;

    while (n && inl) {
        *(current_out++) = *(current_in++) ^ c->partial_buffer.b[n];
        --inl;
        n = (n + 1) % GRASSHOPPER_BLOCK_SIZE;
    }
    EVP_CIPHER_CTX_set_num(ctx, n);
    size_t blocks = inl / GRASSHOPPER_BLOCK_SIZE;

    grasshopper_w128_t *iv_buffer = (grasshopper_w128_t *) iv;
    grasshopper_w128_t tmp;

    // full parts
    for (i = 0; i < blocks; i++) {
        currentInputBlock = (grasshopper_w128_t *) current_in;
        currentOutputBlock = (grasshopper_w128_t *) current_out;
        grasshopper_encrypt_block(&c->c.encrypt_round_keys, iv_buffer,
                                  &c->partial_buffer, &c->c.buffer);
        grasshopper_plus128(&tmp, &c->partial_buffer, currentInputBlock);
        grasshopper_copy128(currentOutputBlock, &tmp);
        ctr128_inc(iv_buffer->b);
        current_in += GRASSHOPPER_BLOCK_SIZE;
        current_out += GRASSHOPPER_BLOCK_SIZE;
    }

    // last part
    lasted = inl - blocks * GRASSHOPPER_BLOCK_SIZE;
    if (lasted > 0) {
        currentInputBlock = (grasshopper_w128_t *) current_in;
        currentOutputBlock = (grasshopper_w128_t *) current_out;
        grasshopper_encrypt_block(&c->c.encrypt_round_keys, iv_buffer,
                                  &c->partial_buffer, &c->c.buffer);
        for (i = 0; i < lasted; i++) {
            currentOutputBlock->b[i] =
                c->partial_buffer.b[i] ^ currentInputBlock->b[i];
        }
        EVP_CIPHER_CTX_set_num(ctx, i);
        ctr128_inc(iv_buffer->b);
    }

    return 1;
}

#define GRASSHOPPER_BLOCK_MASK (GRASSHOPPER_BLOCK_SIZE - 1)
static inline void apply_acpkm_grasshopper(gost_grasshopper_cipher_ctx_ctr *
                                           ctx, unsigned int *num)
{
    if (!ctx->section_size || (*num < ctx->section_size))
        return;
    acpkm_next(&ctx->c);
    *num &= GRASSHOPPER_BLOCK_MASK;
}

/* If meshing is not configured via ctrl (setting section_size)
 * this function works exactly like plain ctr */
int gost_grasshopper_cipher_do_ctracpkm(EVP_CIPHER_CTX *ctx,
                                        unsigned char *out,
                                        const unsigned char *in, size_t inl)
{
    gost_grasshopper_cipher_ctx_ctr *c = EVP_CIPHER_CTX_get_cipher_data(ctx);
    unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
    unsigned int num = EVP_CIPHER_CTX_num(ctx);

    while ((num & GRASSHOPPER_BLOCK_MASK) && inl) {
        *out++ = *in++ ^ c->partial_buffer.b[num & GRASSHOPPER_BLOCK_MASK];
        --inl;
        num++;
    }
    size_t blocks = inl / GRASSHOPPER_BLOCK_SIZE;
    size_t i;
    grasshopper_w128_t tmp;

    // full parts
    for (i = 0; i < blocks; i++) {
        apply_acpkm_grasshopper(c, &num);
        grasshopper_encrypt_block(&c->c.encrypt_round_keys,
                                  (grasshopper_w128_t *) iv,
                                  (grasshopper_w128_t *) & c->partial_buffer,
                                  &c->c.buffer);
        grasshopper_plus128(&tmp, &c->partial_buffer,
                            (grasshopper_w128_t *) in);
        grasshopper_copy128((grasshopper_w128_t *) out, &tmp);
        ctr128_inc(iv);
        in += GRASSHOPPER_BLOCK_SIZE;
        out += GRASSHOPPER_BLOCK_SIZE;
        num += GRASSHOPPER_BLOCK_SIZE;
    }

    // last part
    size_t lasted = inl - blocks * GRASSHOPPER_BLOCK_SIZE;
    if (lasted > 0) {
        apply_acpkm_grasshopper(c, &num);
        grasshopper_encrypt_block(&c->c.encrypt_round_keys,
                                  (grasshopper_w128_t *) iv,
                                  &c->partial_buffer, &c->c.buffer);
        for (i = 0; i < lasted; i++)
            out[i] = c->partial_buffer.b[i] ^ in[i];
        ctr128_inc(iv);
        num += lasted;
    }
    EVP_CIPHER_CTX_set_num(ctx, num);

    return 1;
}

/* ----------------------------------------------------------------------------------------------- */
/*! Функция реализует операцию умножения двух элементов конечного поля \f$ \mathbb F_{2^{128}}\f$,
    порожденного неприводимым многочленом
    \f$ f(x) = x^{128} + x^7 + x^2 + x + 1 \in \mathbb F_2[x]\f$. Для умножения используется
    простейшая реализация, основанная на приведении по модулю после каждого шага алгоритма.        */
/* ----------------------------------------------------------------------------------------------- */
static void gf128_mul_uint64(uint64_t *result, uint64_t *arg1, uint64_t *arg2)
{
    int i = 0, n = 0;
    uint64_t t, s0, s1;
    uint64_t x[2], y[2], z[2];

    BUF_reverse((unsigned char *)x, (unsigned char *)arg1, 16);
    BUF_reverse((unsigned char *)y, (unsigned char *)arg2, 16);

#ifdef L_ENDIAN
    s0 = x[0];
    s1 = x[1];
#else
    s0 = bswap_64(x[0]);
    s1 = bswap_64(x[1]);
#endif

    memset(z, 0, sizeof(uint64_t) * 2);

    /* lower half */
#ifdef L_ENDIAN
    t = y[0];
#else
    t = bswap_64(y[0]);
#endif

    for (i = 0; i < 64; i++) {
        if (t & 0x1) {
            z[0] ^= s0;
            z[1] ^= s1;
        }
        t >>= 1;
        n = s1 >> 63;
        s1 <<= 1;
        s1 ^= (s0 >> 63);
        s0 <<= 1;
        if (n)
            s0 ^= 0x87;
    }

    /* upper half */
#ifdef L_ENDIAN
    t = y[1];
#else
    t = bswap_64(y[1]);
#endif

    for (i = 0; i < 63; i++) {
        if (t & 0x1) {
            z[0] ^= s0;
            z[1] ^= s1;
        }
        t >>= 1;
        n = s1 >> 63;
        s1 <<= 1;
        s1 ^= (s0 >> 63);
        s0 <<= 1;
        if (n)
            s0 ^= 0x87;
    }

    if (t & 0x1) {
        z[0] ^= s0;
        z[1] ^= s1;
    }
#ifndef L_ENDIAN
    z[0] = bswap_64(z[0]);
    z[1] = bswap_64(z[1]);
#endif
    BUF_reverse((unsigned char *)result, (unsigned char *)z, 16);
}

static void hexdump(FILE *f, const char *title, const unsigned char *s, int l)
{
    int n = 0;

    fprintf(f, "%s", title);
    for (; n < l; ++n) {
        if ((n % 16) == 0)
            fprintf(f, "\n%04x", n);
        fprintf(f, " %02x", s[n]);
    }
    fprintf(f, "\n");
}

int gost_grasshopper_cipher_do_mgm(EVP_CIPHER_CTX *ctx, unsigned char *out,
                                   const unsigned char *in, size_t inl)
{
    gost_grasshopper_cipher_ctx_mgm *c = (gost_grasshopper_cipher_ctx_mgm *)
        EVP_CIPHER_CTX_get_cipher_data(ctx);
    unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
    const unsigned char *current_in = in;
    unsigned char *current_out = out;
    grasshopper_w128_t *currentInputBlock;
    grasshopper_w128_t *currentOutputBlock;
    unsigned int n = EVP_CIPHER_CTX_num(ctx);
    size_t lasted;
    size_t i;

    size_t blocks = inl / GRASSHOPPER_BLOCK_SIZE;
    int rest_len = n % GRASSHOPPER_BLOCK_SIZE;
    grasshopper_w128_t h;

    grasshopper_w128_t *iv_buffer = (grasshopper_w128_t *) iv;
    grasshopper_w128_t tmp;

/* ======== Here we deal with associated data =========== */
    if (out == NULL && c->mgm_state == mgm_associated_data) {
        if (n == 0) {
            grasshopper_encrypt_block(&c->c.encrypt_round_keys, c->mgm_iv,
                                      &c->partial_buffer, &c->c.buffer);
            memcpy(c->mgm_iv, &c->partial_buffer, GRASSHOPPER_BLOCK_SIZE);
            hexdump(stderr, "Tag", c->tag, 16);
        }

        if (rest_len != 0) {
            /* Finalize partial_data */
            if (inl + rest_len < GRASSHOPPER_BLOCK_SIZE) {
                memcpy(c->mgm_partial_buffer.b + rest_len, current_in, inl);
                n += inl;
                EVP_CIPHER_CTX_set_num(ctx, n);
                return 1;
            } else {
                memcpy(c->mgm_partial_buffer.b + rest_len, current_in,
                       GRASSHOPPER_BLOCK_SIZE - rest_len);

                grasshopper_encrypt_block(&c->c.encrypt_round_keys, c->mgm_iv,
                                          &h, &c->c.buffer);
                inc_counter(c->mgm_iv->b, 8);

                hexdump(stderr, "Hnext", h.b, 16);
                hexdump(stderr, "Adata", c->mgm_partial_buffer.b, 16);
                /* Galois multiply Hi * Ai */
                gf128_mul_uint64(tmp.q, h.q, c->mgm_partial_buffer.q);

                /* XOR to c->tag */
                grasshopper_plus128(&h, (grasshopper_w128_t *) c->tag, &tmp);
                grasshopper_copy128((grasshopper_w128_t *) c->tag, &h);
                hexdump(stderr, "Tag", c->tag, 16);

                current_in += GRASSHOPPER_BLOCK_SIZE - rest_len;
                inl -= (GRASSHOPPER_BLOCK_SIZE - rest_len);
                n += GRASSHOPPER_BLOCK_SIZE - rest_len;
            }
        }

        while (inl >= GRASSHOPPER_BLOCK_SIZE) {
            currentInputBlock = (grasshopper_w128_t *) current_in;

            grasshopper_encrypt_block(&c->c.encrypt_round_keys, c->mgm_iv,
                                      &h, &c->c.buffer);
            inc_counter(c->mgm_iv->b, 8);

            hexdump(stderr, "Hnext", h.b, 16);
            hexdump(stderr, "Adata", currentInputBlock->b, 16);
            /* Galois multiply */
            gf128_mul_uint64(tmp.q, h.q, currentInputBlock->q);

            /* XOR to c->tag */
            grasshopper_plus128(&h, (grasshopper_w128_t *) c->tag, &tmp);
            grasshopper_copy128((grasshopper_w128_t *) c->tag, &h);
            hexdump(stderr, "Tag", c->tag, 16);

            current_in += GRASSHOPPER_BLOCK_SIZE;
            inl -= GRASSHOPPER_BLOCK_SIZE;
            n += GRASSHOPPER_BLOCK_SIZE;
        }

        if (inl > 0) {
            memcpy(c->mgm_partial_buffer.b, current_in, inl);
            n += inl;
        }

        EVP_CIPHER_CTX_set_num(ctx, n);
        return 1;
    }

    if (out == NULL && in != NULL && inl != 0 && c->mgm_state == mgm_main_data) {
        GOSTerr(GOST_F_GOST_GRASSHOPPER_CIPHER_DO_MGM, GOST_R_BAD_ORDER);
        return 0;
    }

    if (out != NULL && c->mgm_state == mgm_associated_data) {
        memset(c->mgm_partial_buffer.b + rest_len, 0,
               GRASSHOPPER_BLOCK_SIZE - rest_len);

        grasshopper_encrypt_block(&c->c.encrypt_round_keys, c->mgm_iv,
                                  &h, &c->c.buffer);
        inc_counter(c->mgm_iv->b, 8);

        hexdump(stderr, "Hnext", h.b, 16);
        hexdump(stderr, "Padded Adata", c->mgm_partial_buffer.b, 16);
        /* Galois multiply Hi * Ai */
        gf128_mul_uint64(tmp.q, h.q, c->mgm_partial_buffer.q);

        /* XOR to c->tag */
        grasshopper_plus128(&h, (grasshopper_w128_t *) c->tag, &tmp);
        grasshopper_copy128((grasshopper_w128_t *) c->tag, &h);
        hexdump(stderr, "Tag", c->tag, 16);

        /* We finish processing associated data */
        /* Pad rest of mgm_partial_buffer */
        /* Process last block */
        c->ad_length = n;
        n = 0;
        rest_len = 0;
        EVP_CIPHER_CTX_set_num(ctx, 0);
        c->mgm_state = mgm_main_data;

        fprintf(stderr, "============= Deal with main data\n");
    }

/* ======== Here we deal with main data =========== */
    if (n == 0) {
        /* actual IV derived from nonce */
        grasshopper_encrypt_block(&c->c.encrypt_round_keys, iv_buffer,
                                  &c->partial_buffer, &c->c.buffer);
        memcpy(iv, c->partial_buffer.b, GRASSHOPPER_BLOCK_SIZE);
        //hexdump(stderr, "Y1", iv, 16);
    }

    while (rest_len && inl) {
        *(current_out++) = *(current_in++) ^ c->partial_buffer.b[rest_len];
        c->partial_buffer.b[rest_len] = *(current_out - 1);

        --inl;
        n++;
        rest_len++;
        if (rest_len == GRASSHOPPER_BLOCK_SIZE) {
            rest_len = 0;
            grasshopper_encrypt_block(&c->c.encrypt_round_keys, c->mgm_iv,
                                      &h, &c->c.buffer);
            inc_counter(c->mgm_iv->b, 8);
            hexdump(stderr, "Hnext", h.b, 16);
            hexdump(stderr, "Ciphertext", c->partial_buffer.b, 16);
            /* Galois multiply Hi * Ai */
            gf128_mul_uint64(tmp.q, h.q, c->partial_buffer.q);

            /* XOR to c->tag */
            grasshopper_plus128(&h, (grasshopper_w128_t *) c->tag, &tmp);
            grasshopper_copy128((grasshopper_w128_t *) c->tag, &h);
            hexdump(stderr, "Tag", c->tag, 16);
        }
    }

    // full parts
    for (i = 0; i < blocks; i++) {
        currentInputBlock = (grasshopper_w128_t *) current_in;
        currentOutputBlock = (grasshopper_w128_t *) current_out;
        grasshopper_encrypt_block(&c->c.encrypt_round_keys, iv_buffer,
                                  &c->partial_buffer, &c->c.buffer);
        grasshopper_plus128(&tmp, &c->partial_buffer, currentInputBlock);
        grasshopper_copy128(currentOutputBlock, &tmp);
        //hexdump(stderr, "Ciphertext", currentOutputBlock->b, 16);

        grasshopper_encrypt_block(&c->c.encrypt_round_keys, c->mgm_iv,
                                  &h, &c->c.buffer);
        inc_counter(c->mgm_iv->b, 8);
        hexdump(stderr, "Hnext", h.b, 16);
        hexdump(stderr, "Ciphertext", currentOutputBlock->b, 16);
        /* Galois multiply Hi * Ai */
        gf128_mul_uint64(tmp.q, h.q, currentOutputBlock->q);

        /* XOR to c->tag */
        grasshopper_plus128(&h, (grasshopper_w128_t *) c->tag, &tmp);
        grasshopper_copy128((grasshopper_w128_t *) c->tag, &h);
        hexdump(stderr, "Tag", c->tag, 16);

        ctr128_inc(iv_buffer->b);
        current_in += GRASSHOPPER_BLOCK_SIZE;
        current_out += GRASSHOPPER_BLOCK_SIZE;
        n += GRASSHOPPER_BLOCK_SIZE;
    }

    EVP_CIPHER_CTX_set_num(ctx, n);

    // last part
    lasted = inl - blocks * GRASSHOPPER_BLOCK_SIZE;
    if (lasted > 0) {
        currentInputBlock = (grasshopper_w128_t *) current_in;
        currentOutputBlock = (grasshopper_w128_t *) current_out;
        grasshopper_encrypt_block(&c->c.encrypt_round_keys, iv_buffer,
                                  &c->partial_buffer, &c->c.buffer);
        for (i = 0; i < lasted; i++) {
            currentOutputBlock->b[i] =
                c->partial_buffer.b[i] ^ currentInputBlock->b[i];
            c->partial_buffer.b[i] = currentOutputBlock->b[i];
        }
        EVP_CIPHER_CTX_set_num(ctx, n + i);
        ctr128_inc(iv_buffer->b);
    }

    /* Final step */
    if (in == NULL && inl == 0) {
        unsigned char len_buf[16];
        uint64_t a_len = 0, p_len = 0;

        if (rest_len != 0) {
            memset(c->partial_buffer.b + rest_len, 0,
                   GRASSHOPPER_BLOCK_SIZE - rest_len);
            grasshopper_encrypt_block(&c->c.encrypt_round_keys, c->mgm_iv, &h,
                                      &c->c.buffer);
            inc_counter(c->mgm_iv->b, 8);
            hexdump(stderr, "Hnext", h.b, 16);
            hexdump(stderr, "Padded ciphertext", c->partial_buffer.b, 16);
            /* Galois multiply Hi * Ai */
            gf128_mul_uint64(tmp.q, h.q, c->partial_buffer.q);

            /* XOR to c->tag */
            grasshopper_plus128(&h, (grasshopper_w128_t *) c->tag, &tmp);
            grasshopper_copy128((grasshopper_w128_t *) c->tag, &h);
            hexdump(stderr, "Tag", c->tag, 16);
        }

        a_len = c->ad_length << 3;
        p_len = (c->mgm_state == mgm_associated_data) ? 0 : n << 3;

#ifdef L_ENDIAN
        a_len = bswap_64(a_len);
        p_len = bswap_64(p_len);
#endif
        memset(len_buf, 0, 16);

        memcpy(len_buf, &a_len, sizeof(a_len));
        memcpy(len_buf + sizeof(a_len), &p_len, sizeof(p_len));
        grasshopper_encrypt_block(&c->c.encrypt_round_keys, c->mgm_iv,
                                  &h, &c->c.buffer);

        hexdump(stderr, "Hlast", h.b, 16);
        hexdump(stderr, "Lenbuf", len_buf, 16);
        /* Galois multiply Hi * Ai */
        gf128_mul_uint64(tmp.q, h.q, (uint64_t *)len_buf);

        /* XOR to c->tag */
        grasshopper_plus128(&h, (grasshopper_w128_t *) c->tag, &tmp);
        grasshopper_copy128((grasshopper_w128_t *) c->tag, &h);
        hexdump(stderr, "Tag", c->tag, 16);

        /* Final tag calculation */
        grasshopper_encrypt_block(&c->c.encrypt_round_keys,
                                  (grasshopper_w128_t *) c->tag,
                                  (grasshopper_w128_t *) c->final_tag,
                                  &c->c.buffer);
    }

    return 1;
}

/*
 * Fixed 128-bit IV implementation make shift regiser redundant.
 */
static void gost_grasshopper_cnt_next(gost_grasshopper_cipher_ctx_ofb * ctx,
                                      grasshopper_w128_t * iv,
                                      grasshopper_w128_t * buf)
{
    memcpy(&ctx->buffer1, iv, 16);
    grasshopper_encrypt_block(&ctx->c.encrypt_round_keys, &ctx->buffer1,
                              buf, &ctx->c.buffer);
    memcpy(iv, buf, 16);
}

int gost_grasshopper_cipher_do_ofb(EVP_CIPHER_CTX *ctx, unsigned char *out,
                                   const unsigned char *in, size_t inl)
{
    gost_grasshopper_cipher_ctx_ofb *c = (gost_grasshopper_cipher_ctx_ofb *)
        EVP_CIPHER_CTX_get_cipher_data(ctx);
    const unsigned char *in_ptr = in;
    unsigned char *out_ptr = out;
    unsigned char *buf = EVP_CIPHER_CTX_buf_noconst(ctx);
    unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
    int num = EVP_CIPHER_CTX_num(ctx);
    size_t i = 0;
    size_t j;

    /* process partial block if any */
    if (num > 0) {
        for (j = (size_t)num, i = 0; j < GRASSHOPPER_BLOCK_SIZE && i < inl;
             j++, i++, in_ptr++, out_ptr++) {
            *out_ptr = buf[j] ^ (*in_ptr);
        }
        if (j == GRASSHOPPER_BLOCK_SIZE) {
            EVP_CIPHER_CTX_set_num(ctx, 0);
        } else {
            EVP_CIPHER_CTX_set_num(ctx, (int)j);
            return 1;
        }
    }

    for (; i + GRASSHOPPER_BLOCK_SIZE <
         inl;
         i += GRASSHOPPER_BLOCK_SIZE, in_ptr +=
         GRASSHOPPER_BLOCK_SIZE, out_ptr += GRASSHOPPER_BLOCK_SIZE) {
        /*
         * block cipher current iv
         */
        /* Encrypt */
        gost_grasshopper_cnt_next(c, (grasshopper_w128_t *) iv,
                                  (grasshopper_w128_t *) buf);

        /*
         * xor next block of input text with it and output it
         */
        /*
         * output this block
         */
        for (j = 0; j < GRASSHOPPER_BLOCK_SIZE; j++) {
            out_ptr[j] = buf[j] ^ in_ptr[j];
        }
    }

    /* Process rest of buffer */
    if (i < inl) {
        gost_grasshopper_cnt_next(c, (grasshopper_w128_t *) iv,
                                  (grasshopper_w128_t *) buf);
        for (j = 0; i < inl; j++, i++) {
            out_ptr[j] = buf[j] ^ in_ptr[j];
        }
        EVP_CIPHER_CTX_set_num(ctx, (int)j);
    } else {
        EVP_CIPHER_CTX_set_num(ctx, 0);
    }

    return 1;
}

int gost_grasshopper_cipher_do_cfb(EVP_CIPHER_CTX *ctx, unsigned char *out,
                                   const unsigned char *in, size_t inl)
{
    gost_grasshopper_cipher_ctx *c =
        (gost_grasshopper_cipher_ctx *) EVP_CIPHER_CTX_get_cipher_data(ctx);
    const unsigned char *in_ptr = in;
    unsigned char *out_ptr = out;
    unsigned char *buf = EVP_CIPHER_CTX_buf_noconst(ctx);
    unsigned char *iv = EVP_CIPHER_CTX_iv_noconst(ctx);
    bool encrypting = (bool) EVP_CIPHER_CTX_encrypting(ctx);
    int num = EVP_CIPHER_CTX_num(ctx);
    size_t i = 0;
    size_t j = 0;

    /* process partial block if any */
    if (num > 0) {
        for (j = (size_t)num, i = 0; j < GRASSHOPPER_BLOCK_SIZE && i < inl;
             j++, i++, in_ptr++, out_ptr++) {
            if (!encrypting) {
                buf[j + GRASSHOPPER_BLOCK_SIZE] = *in_ptr;
            }
            *out_ptr = buf[j] ^ (*in_ptr);
            if (encrypting) {
                buf[j + GRASSHOPPER_BLOCK_SIZE] = *out_ptr;
            }
        }
        if (j == GRASSHOPPER_BLOCK_SIZE) {
            memcpy(iv, buf + GRASSHOPPER_BLOCK_SIZE, GRASSHOPPER_BLOCK_SIZE);
            EVP_CIPHER_CTX_set_num(ctx, 0);
        } else {
            EVP_CIPHER_CTX_set_num(ctx, (int)j);
            return 1;
        }
    }

    for (; i + GRASSHOPPER_BLOCK_SIZE <
         inl;
         i += GRASSHOPPER_BLOCK_SIZE, in_ptr +=
         GRASSHOPPER_BLOCK_SIZE, out_ptr += GRASSHOPPER_BLOCK_SIZE) {
        /*
         * block cipher current iv
         */
        grasshopper_encrypt_block(&c->encrypt_round_keys,
                                  (grasshopper_w128_t *) iv,
                                  (grasshopper_w128_t *) buf, &c->buffer);
        /*
         * xor next block of input text with it and output it
         */
        /*
         * output this block
         */
        if (!encrypting) {
            memcpy(iv, in_ptr, GRASSHOPPER_BLOCK_SIZE);
        }
        for (j = 0; j < GRASSHOPPER_BLOCK_SIZE; j++) {
            out_ptr[j] = buf[j] ^ in_ptr[j];
        }
        /* Encrypt */
        /* Next iv is next block of cipher text */
        if (encrypting) {
            memcpy(iv, out_ptr, GRASSHOPPER_BLOCK_SIZE);
        }
    }

    /* Process rest of buffer */
    if (i < inl) {
        grasshopper_encrypt_block(&c->encrypt_round_keys,
                                  (grasshopper_w128_t *) iv,
                                  (grasshopper_w128_t *) buf, &c->buffer);
        if (!encrypting) {
            memcpy(buf + GRASSHOPPER_BLOCK_SIZE, in_ptr, inl - i);
        }
        for (j = 0; i < inl; j++, i++) {
            out_ptr[j] = buf[j] ^ in_ptr[j];
        }
        EVP_CIPHER_CTX_set_num(ctx, (int)j);
        if (encrypting) {
            memcpy(buf + GRASSHOPPER_BLOCK_SIZE, out_ptr, j);
        }
    } else {
        EVP_CIPHER_CTX_set_num(ctx, 0);
    }

    return 1;
}

int gost_grasshopper_cipher_cleanup(EVP_CIPHER_CTX *ctx)
{
    gost_grasshopper_cipher_ctx *c =
        (gost_grasshopper_cipher_ctx *) EVP_CIPHER_CTX_get_cipher_data(ctx);

    if (!c)
        return 1;

    struct GRASSHOPPER_CIPHER_PARAMS *params = &gost_cipher_params[c->type];

    gost_grasshopper_cipher_destroy(c);
    if (params->destroy_cipher != NULL) {
        params->destroy_cipher(c);
    }

    EVP_CIPHER_CTX_set_app_data(ctx, NULL);

    return 1;
}

int gost_grasshopper_set_asn1_parameters(EVP_CIPHER_CTX *ctx, ASN1_TYPE *params)
{
    int len = 0;
    unsigned char *buf = NULL;
    ASN1_OCTET_STRING *os = NULL;

    os = ASN1_OCTET_STRING_new();

    if (!os || !ASN1_OCTET_STRING_set(os, buf, len)) {
        OPENSSL_free(buf);
        GOSTerr(GOST_F_GOST_GRASSHOPPER_SET_ASN1_PARAMETERS,
                ERR_R_MALLOC_FAILURE);
        return 0;
    }
    OPENSSL_free(buf);

    ASN1_TYPE_set(params, V_ASN1_SEQUENCE, os);
    return 1;
}

GRASSHOPPER_INLINE int gost_grasshopper_get_asn1_parameters(EVP_CIPHER_CTX
                                                            *ctx, ASN1_TYPE
                                                            *params)
{
    int ret = -1;

    if (ASN1_TYPE_get(params) != V_ASN1_SEQUENCE) {
        return ret;
    }

    return 1;
}

int gost_grasshopper_cipher_ctl(EVP_CIPHER_CTX *ctx, int type, int arg,
                                void *ptr)
{
    switch (type) {
    case EVP_CTRL_RAND_KEY:{
            if (RAND_bytes
                ((unsigned char *)ptr, EVP_CIPHER_CTX_key_length(ctx)) <= 0) {
                GOSTerr(GOST_F_GOST_GRASSHOPPER_CIPHER_CTL, GOST_R_RNG_ERROR);
                return -1;
            }
            break;
        }
    case EVP_CTRL_KEY_MESH:{
            gost_grasshopper_cipher_ctx_ctr *c =
                EVP_CIPHER_CTX_get_cipher_data(ctx);
            if (c->c.type != GRASSHOPPER_CIPHER_CTRACPKM || !arg
                || (arg % GRASSHOPPER_BLOCK_SIZE))
                return -1;
            c->section_size = arg;
            break;
        }
#ifdef EVP_CTRL_TLS1_2_TLSTREE
    case EVP_CTRL_TLS1_2_TLSTREE:
        {
            unsigned char newkey[32];
            int mode = EVP_CIPHER_CTX_mode(ctx);
            static const unsigned char zeroseq[8];
            gost_grasshopper_cipher_ctx_ctr *ctr_ctx = NULL;
            gost_grasshopper_cipher_ctx *c = NULL;

            unsigned char adjusted_iv[16];
            unsigned char seq[8];
            int j;
            if (mode != EVP_CIPH_CTR_MODE)
                return -1;

            ctr_ctx = (gost_grasshopper_cipher_ctx_ctr *)
                EVP_CIPHER_CTX_get_cipher_data(ctx);
            c = &(ctr_ctx->c);

            memcpy(seq, ptr, 8);
            if (EVP_CIPHER_CTX_encrypting(ctx)) {
                /*
                 * OpenSSL increments seq after mac calculation.
                 * As we have Mac-Then-Encrypt, we need decrement it here on encryption
                 * to derive the key correctly.
                 * */
                if (memcmp(seq, zeroseq, 8) != 0) {
                    for (j = 7; j >= 0; j--) {
                        if (seq[j] != 0) {
                            seq[j]--;
                            break;
                        } else
                            seq[j] = 0xFF;
                    }
                }
            }
            if (gost_tlstree(NID_grasshopper_cbc, c->master_key.k.b, newkey,
                             (const unsigned char *)seq) > 0) {
                memset(adjusted_iv, 0, 16);
                memcpy(adjusted_iv, EVP_CIPHER_CTX_original_iv(ctx), 8);
                for (j = 7; j >= 0; j--) {
                    int adj_byte, carry = 0;
                    adj_byte = adjusted_iv[j] + seq[j] + carry;
                    carry = (adj_byte > 255) ? 1 : 0;
                    adjusted_iv[j] = adj_byte & 0xFF;
                }
                EVP_CIPHER_CTX_set_num(ctx, 0);
                memcpy(EVP_CIPHER_CTX_iv_noconst(ctx), adjusted_iv, 16);

                gost_grasshopper_cipher_key(c, newkey);
                return 1;
            }
        }
        return -1;
#endif
    case EVP_CTRL_AEAD_GET_TAG:
    case EVP_CTRL_AEAD_SET_TAG:
        {
            gost_grasshopper_cipher_ctx_mgm *mgm_ctx = NULL;
            gost_grasshopper_cipher_ctx *c = NULL;
            int taglen = arg;
            unsigned char *tag = ptr;

            mgm_ctx = (gost_grasshopper_cipher_ctx_mgm *)
                EVP_CIPHER_CTX_get_cipher_data(ctx);
            c = (gost_grasshopper_cipher_ctx *) mgm_ctx;

            if (c->type != GRASSHOPPER_CIPHER_MGM)
                return -1;

            if (taglen > 16) {
                GOSTerr(GOST_F_GOST_GRASSHOPPER_CIPHER_CTL,
                        GOST_R_INVALID_TAG_LENGTH);
                return -1;
            }

            if (type == EVP_CTRL_AEAD_GET_TAG)
                memcpy(tag, mgm_ctx->final_tag, taglen);
            else
                memcpy(mgm_ctx->final_tag, tag, taglen);

            return 1;
        }
    default:
        GOSTerr(GOST_F_GOST_GRASSHOPPER_CIPHER_CTL,
                GOST_R_UNSUPPORTED_CIPHER_CTL_COMMAND);
        return -1;
    }
    return 1;
}

GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_create(int
                                                              cipher_type, int
                                                              block_size)
{
    return EVP_CIPHER_meth_new(cipher_type, block_size /* block_size */ ,
                               GRASSHOPPER_KEY_SIZE /* key_size */ );
}

const int cipher_gost_grasshopper_setup(EVP_CIPHER *cipher, uint8_t mode,
                                        int iv_size, bool padding,
                                        int extra_flags)
{
    return EVP_CIPHER_meth_set_iv_length(cipher, iv_size)
        && EVP_CIPHER_meth_set_flags(cipher,
                                     (unsigned long)(mode |
                                                     ((!padding) ?
                                                      EVP_CIPH_NO_PADDING :
                                                      0) | ((iv_size >
                                                             0) ?
                                                            EVP_CIPH_CUSTOM_IV
                                                            : 0) |
                                                     EVP_CIPH_RAND_KEY |
                                                     EVP_CIPH_ALWAYS_CALL_INIT |
                                                     extra_flags)
        )
        && EVP_CIPHER_meth_set_cleanup(cipher, gost_grasshopper_cipher_cleanup)
        && EVP_CIPHER_meth_set_set_asn1_params(cipher,
                                               gost_grasshopper_set_asn1_parameters)
        && EVP_CIPHER_meth_set_get_asn1_params(cipher,
                                               gost_grasshopper_get_asn1_parameters)
        && EVP_CIPHER_meth_set_ctrl(cipher, gost_grasshopper_cipher_ctl)
        && EVP_CIPHER_meth_set_do_cipher(cipher, gost_grasshopper_cipher_do);
}

const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper(uint8_t mode,
                                                             uint8_t num)
{
    EVP_CIPHER **cipher;
    struct GRASSHOPPER_CIPHER_PARAMS *params;

    cipher = &gost_grasshopper_ciphers[num];

    if (*cipher == NULL) {
        params = &gost_cipher_params[num];

        int nid = params->nid;
        grasshopper_init_cipher_func init_cipher = params->init_cipher;
        int block_size = params->block_size;
        int ctx_size = params->ctx_size;
        int iv_size = params->iv_size;
        bool padding = params->padding;

        int extra_flags = (num == GRASSHOPPER_CIPHER_MGM) ?
            EVP_CIPH_FLAG_CUSTOM_CIPHER | EVP_CIPH_FLAG_AEAD_CIPHER : 0;

        *cipher = cipher_gost_grasshopper_create(nid, block_size);
        if (*cipher == NULL) {
            return NULL;
        }

        if (!cipher_gost_grasshopper_setup
            (*cipher, mode, iv_size, padding, extra_flags)
            || !EVP_CIPHER_meth_set_init(*cipher, init_cipher)
            || !EVP_CIPHER_meth_set_impl_ctx_size(*cipher, ctx_size)) {
            EVP_CIPHER_meth_free(*cipher);
            *cipher = NULL;
        }
    }

    return *cipher;
}

const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_ecb()
{
    return cipher_gost_grasshopper(EVP_CIPH_ECB_MODE, GRASSHOPPER_CIPHER_ECB);
}

const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_cbc()
{
    return cipher_gost_grasshopper(EVP_CIPH_CBC_MODE, GRASSHOPPER_CIPHER_CBC);
}

const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_ofb()
{
    return cipher_gost_grasshopper(EVP_CIPH_OFB_MODE, GRASSHOPPER_CIPHER_OFB);
}

const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_cfb()
{
    return cipher_gost_grasshopper(EVP_CIPH_CFB_MODE, GRASSHOPPER_CIPHER_CFB);
}

const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_ctr()
{
    return cipher_gost_grasshopper(EVP_CIPH_CTR_MODE, GRASSHOPPER_CIPHER_CTR);
}

const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_ctracpkm()
{
    return cipher_gost_grasshopper(EVP_CIPH_CTR_MODE,
                                   GRASSHOPPER_CIPHER_CTRACPKM);
}

const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_mgm()
{
#ifndef NID_kuznyechik_mgm
    return NULL;
#else
    return cipher_gost_grasshopper(EVP_CIPH_CTR_MODE, GRASSHOPPER_CIPHER_MGM);
#endif
}

void cipher_gost_grasshopper_destroy(void)
{
    EVP_CIPHER_meth_free(gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_ECB]);
    gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_ECB] = NULL;
    EVP_CIPHER_meth_free(gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_CBC]);
    gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_CBC] = NULL;
    EVP_CIPHER_meth_free(gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_OFB]);
    gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_OFB] = NULL;
    EVP_CIPHER_meth_free(gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_CFB]);
    gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_CFB] = NULL;
    EVP_CIPHER_meth_free(gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_CTR]);
    gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_CTR] = NULL;
    EVP_CIPHER_meth_free(gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_CTRACPKM]);
    gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_CTRACPKM] = NULL;
    EVP_CIPHER_meth_free(gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_MGM]);
    gost_grasshopper_ciphers[GRASSHOPPER_CIPHER_MGM] = NULL;
}