]> wagner.pp.ru Git - openssl-gost/engine.git/blobdiff - gost_grasshopper_cipher.c
Debug + formatting
[openssl-gost/engine.git] / gost_grasshopper_cipher.c
index 21d503814e2c037d55e51eef5c8a7c711f70bbbb..a5852301496d913ed589d3ed505a3984de8ae2c8 100644 (file)
@@ -11,7 +11,9 @@
 #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"
@@ -23,21 +25,25 @@ enum GRASSHOPPER_CIPHER_TYPE {
     GRASSHOPPER_CIPHER_CFB,
     GRASSHOPPER_CIPHER_CTR,
     GRASSHOPPER_CIPHER_CTRACPKM,
+    GRASSHOPPER_CIPHER_MGM,
 };
 
-static EVP_CIPHER *gost_grasshopper_ciphers[6] = {
+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;
@@ -50,7 +56,7 @@ struct GRASSHOPPER_CIPHER_PARAMS {
     bool padding;
 };
 
-static struct GRASSHOPPER_CIPHER_PARAMS gost_cipher_params[6] = {
+static struct GRASSHOPPER_CIPHER_PARAMS gost_cipher_params[7] = {
     [GRASSHOPPER_CIPHER_ECB] = {
                                 NID_grasshopper_ecb,
                                 gost_grasshopper_cipher_init_ecb,
@@ -114,6 +120,29 @@ static struct GRASSHOPPER_CIPHER_PARAMS gost_cipher_params[6] = {
                                      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 */
@@ -203,6 +232,15 @@ gost_grasshopper_cipher_destroy_ctr(gost_grasshopper_cipher_ctx * 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)
@@ -219,6 +257,19 @@ int gost_grasshopper_cipher_init(EVP_CIPHER_CTX *ctx,
     }
 
     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));
     }
@@ -300,6 +351,21 @@ GRASSHOPPER_INLINE int gost_grasshopper_cipher_init_ctracpkm(EVP_CIPHER_CTX
     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,
@@ -523,6 +589,360 @@ int gost_grasshopper_cipher_do_ctracpkm(EVP_CIPHER_CTX *ctx,
     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.
  */
@@ -763,26 +1183,79 @@ int gost_grasshopper_cipher_ctl(EVP_CIPHER_CTX *ctx, int type, int arg,
 #ifdef EVP_CTRL_TLS1_2_TLSTREE
     case EVP_CTRL_TLS1_2_TLSTREE:
         {
-            unsigned char newkey[32];
-            int mode = EVP_CIPHER_CTX_mode(ctx);
-            gost_grasshopper_cipher_ctx_ctr *ctr_ctx = NULL;
+          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, carry;
+          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,carry=0; j>=0; j--)
+            {
+              int adj_byte = adjusted_iv[j]+seq[j]+carry;
+              carry = (adj_byte > 255) ? 1 : 0;
+              adjusted_iv[j] = adj_byte & 0xFF;
+            }
+        }
+        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;
 
-            if (mode != EVP_CIPH_CTR_MODE)
-                return -1;
-
-            ctr_ctx = (gost_grasshopper_cipher_ctx_ctr *)
+            mgm_ctx = (gost_grasshopper_cipher_ctx_mgm *)
                 EVP_CIPHER_CTX_get_cipher_data(ctx);
-            c = &(ctr_ctx->c);
+            c = (gost_grasshopper_cipher_ctx *) mgm_ctx;
 
-            if (gost_tlstree(NID_grasshopper_cbc, c->master_key.k.b, newkey,
-                             (const unsigned char *)ptr) > 0) {
-                gost_grasshopper_cipher_key(c, newkey);
-                return 1;
+            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;
         }
-        return -1;
-#endif
     default:
         GOSTerr(GOST_F_GOST_GRASSHOPPER_CIPHER_CTL,
                 GOST_R_UNSUPPORTED_CIPHER_CTL_COMMAND);
@@ -800,7 +1273,8 @@ GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_create(int
 }
 
 const int cipher_gost_grasshopper_setup(EVP_CIPHER *cipher, uint8_t mode,
-                                        int iv_size, bool padding)
+                                        int iv_size, bool padding,
+                                        int extra_flags)
 {
     return EVP_CIPHER_meth_set_iv_length(cipher, iv_size)
         && EVP_CIPHER_meth_set_flags(cipher,
@@ -812,7 +1286,8 @@ const int cipher_gost_grasshopper_setup(EVP_CIPHER *cipher, uint8_t mode,
                                                             EVP_CIPH_CUSTOM_IV
                                                             : 0) |
                                                      EVP_CIPH_RAND_KEY |
-                                                     EVP_CIPH_ALWAYS_CALL_INIT)
+                                                     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,
@@ -841,12 +1316,16 @@ const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper(uint8_t mode,
         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)
+        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);
@@ -888,6 +1367,15 @@ const GRASSHOPPER_INLINE EVP_CIPHER *cipher_gost_grasshopper_ctracpkm()
                                    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]);
@@ -902,4 +1390,6 @@ void cipher_gost_grasshopper_destroy(void)
     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;
 }