crypto/cipher/e_tls.c - boringssl - Git at Google

 /* Copyright (c) 2014, Google Inc.
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

 #include <assert.h>
 #include <limits.h>
 #include <string.h>

 #include <openssl/aead.h>
 #include <openssl/cipher.h>
 #include <openssl/err.h>
 #include <openssl/hmac.h>
 #include <openssl/mem.h>
 #include <openssl/sha.h>
 #include <openssl/type_check.h>

 #include "../crypto/internal.h"
 #include "internal.h"


 typedef struct {
   EVP_CIPHER_CTX cipher_ctx;
   HMAC_CTX hmac_ctx;
   /* mac_key is the portion of the key used for the MAC. It is retained
    * separately for the constant-time CBC code. */
   uint8_t mac_key[EVP_MAX_MD_SIZE];
   uint8_t mac_key_len;
   /* implicit_iv is one iff this is a pre-TLS-1.1 CBC cipher without an explicit
    * IV. */
   char implicit_iv;
 } AEAD_TLS_CTX;

 OPENSSL_COMPILE_ASSERT(EVP_MAX_MD_SIZE < 256, mac_key_len_fits_in_uint8_t);

 static void aead_tls_cleanup(EVP_AEAD_CTX *ctx) {
   AEAD_TLS_CTX *tls_ctx = (AEAD_TLS_CTX *)ctx->aead_state;
   EVP_CIPHER_CTX_cleanup(&tls_ctx->cipher_ctx);
   HMAC_CTX_cleanup(&tls_ctx->hmac_ctx);
   OPENSSL_cleanse(&tls_ctx->mac_key, sizeof(tls_ctx->mac_key));
   OPENSSL_free(tls_ctx);
   ctx->aead_state = NULL;
 }

 static int aead_tls_init(EVP_AEAD_CTX *ctx, const uint8_t *key, size_t key_len,
                          size_t tag_len, enum evp_aead_direction_t dir,
                          const EVP_CIPHER *cipher, const EVP_MD *md,
                          char implicit_iv) {
   if (tag_len != EVP_AEAD_DEFAULT_TAG_LENGTH &&
       tag_len != EVP_MD_size(md)) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_TAG_SIZE);
     return 0;
   }

   if (key_len != EVP_AEAD_key_length(ctx->aead)) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH);
     return 0;
   }

   size_t mac_key_len = EVP_MD_size(md);
   size_t enc_key_len = EVP_CIPHER_key_length(cipher);
   assert(mac_key_len + enc_key_len +
          (implicit_iv ? EVP_CIPHER_iv_length(cipher) : 0) == key_len);
   /* Although EVP_rc4() is a variable-length cipher, the default key size is
    * correct for TLS. */

   AEAD_TLS_CTX *tls_ctx = OPENSSL_malloc(sizeof(AEAD_TLS_CTX));
   if (tls_ctx == NULL) {
     OPENSSL_PUT_ERROR(CIPHER, ERR_R_MALLOC_FAILURE);
     return 0;
   }
   EVP_CIPHER_CTX_init(&tls_ctx->cipher_ctx);
   HMAC_CTX_init(&tls_ctx->hmac_ctx);
   assert(mac_key_len <= EVP_MAX_MD_SIZE);
   memcpy(tls_ctx->mac_key, key, mac_key_len);
   tls_ctx->mac_key_len = (uint8_t)mac_key_len;
   tls_ctx->implicit_iv = implicit_iv;

   ctx->aead_state = tls_ctx;
   if (!EVP_CipherInit_ex(&tls_ctx->cipher_ctx, cipher, NULL, &key[mac_key_len],
                          implicit_iv ? &key[mac_key_len + enc_key_len] : NULL,
                          dir == evp_aead_seal) ||
       !HMAC_Init_ex(&tls_ctx->hmac_ctx, key, mac_key_len, md, NULL)) {
     aead_tls_cleanup(ctx);
     ctx->aead_state = NULL;
     return 0;
   }
   EVP_CIPHER_CTX_set_padding(&tls_ctx->cipher_ctx, 0);

   return 1;
 }

 static int aead_tls_seal(const EVP_AEAD_CTX *ctx, uint8_t *out,
                          size_t *out_len, size_t max_out_len,
                          const uint8_t *nonce, size_t nonce_len,
                          const uint8_t *in, size_t in_len,
                          const uint8_t *ad, size_t ad_len) {
   AEAD_TLS_CTX *tls_ctx = (AEAD_TLS_CTX *)ctx->aead_state;
   size_t total = 0;

   if (!tls_ctx->cipher_ctx.encrypt) {
     /* Unlike a normal AEAD, a TLS AEAD may only be used in one direction. */
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_OPERATION);
     return 0;

   }

   if (in_len + EVP_AEAD_max_overhead(ctx->aead) < in_len ||
       in_len > INT_MAX) {
     /* EVP_CIPHER takes int as input. */
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
     return 0;
   }

   if (max_out_len < in_len + EVP_AEAD_max_overhead(ctx->aead)) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
     return 0;
   }

   if (nonce_len != EVP_AEAD_nonce_length(ctx->aead)) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_NONCE_SIZE);
     return 0;
   }

   if (ad_len != 13 - 2 /* length bytes */) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_AD_SIZE);
     return 0;
   }

   /* To allow for CBC mode which changes cipher length, |ad| doesn't include the
    * length for legacy ciphers. */
   uint8_t ad_extra[2];
   ad_extra[0] = (uint8_t)(in_len >> 8);
   ad_extra[1] = (uint8_t)(in_len & 0xff);

   /* Compute the MAC. This must be first in case the operation is being done
    * in-place. */
   uint8_t mac[EVP_MAX_MD_SIZE];
   unsigned mac_len;
   HMAC_CTX hmac_ctx;
   HMAC_CTX_init(&hmac_ctx);
   if (!HMAC_CTX_copy_ex(&hmac_ctx, &tls_ctx->hmac_ctx) ||
       !HMAC_Update(&hmac_ctx, ad, ad_len) ||
       !HMAC_Update(&hmac_ctx, ad_extra, sizeof(ad_extra)) ||
       !HMAC_Update(&hmac_ctx, in, in_len) ||
       !HMAC_Final(&hmac_ctx, mac, &mac_len)) {
     HMAC_CTX_cleanup(&hmac_ctx);
     return 0;
   }
   HMAC_CTX_cleanup(&hmac_ctx);

   /* Configure the explicit IV. */
   if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
       !tls_ctx->implicit_iv &&
       !EVP_EncryptInit_ex(&tls_ctx->cipher_ctx, NULL, NULL, NULL, nonce)) {
     return 0;
   }

   /* Encrypt the input. */
   int len;
   if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out, &len, in,
                          (int)in_len)) {
     return 0;
   }
   total = len;

   /* Feed the MAC into the cipher. */
   if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out + total, &len, mac,
                          (int)mac_len)) {
     return 0;
   }
   total += len;

   unsigned block_size = EVP_CIPHER_CTX_block_size(&tls_ctx->cipher_ctx);
   if (block_size > 1) {
     assert(block_size <= 256);
     assert(EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE);

     /* Compute padding and feed that into the cipher. */
     uint8_t padding[256];
     unsigned padding_len = block_size - ((in_len + mac_len) % block_size);
     memset(padding, padding_len - 1, padding_len);
     if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out + total, &len, padding,
                            (int)padding_len)) {
       return 0;
     }
     total += len;
   }

   if (!EVP_EncryptFinal_ex(&tls_ctx->cipher_ctx, out + total, &len)) {
     return 0;
   }
   total += len;

   *out_len = total;
   return 1;
 }

 static int aead_tls_open(const EVP_AEAD_CTX *ctx, uint8_t *out,
                          size_t *out_len, size_t max_out_len,
                          const uint8_t *nonce, size_t nonce_len,
                          const uint8_t *in, size_t in_len,
                          const uint8_t *ad, size_t ad_len) {
   AEAD_TLS_CTX *tls_ctx = (AEAD_TLS_CTX *)ctx->aead_state;

   if (tls_ctx->cipher_ctx.encrypt) {
     /* Unlike a normal AEAD, a TLS AEAD may only be used in one direction. */
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_OPERATION);
     return 0;

   }

   if (in_len < HMAC_size(&tls_ctx->hmac_ctx)) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
     return 0;
   }

   if (max_out_len < in_len) {
     /* This requires that the caller provide space for the MAC, even though it
      * will always be removed on return. */
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
     return 0;
   }

   if (nonce_len != EVP_AEAD_nonce_length(ctx->aead)) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_NONCE_SIZE);
     return 0;
   }

   if (ad_len != 13 - 2 /* length bytes */) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_AD_SIZE);
     return 0;
   }

   if (in_len > INT_MAX) {
     /* EVP_CIPHER takes int as input. */
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
     return 0;
   }

   /* Configure the explicit IV. */
   if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
       !tls_ctx->implicit_iv &&
       !EVP_DecryptInit_ex(&tls_ctx->cipher_ctx, NULL, NULL, NULL, nonce)) {
     return 0;
   }

   /* Decrypt to get the plaintext + MAC + padding. */
   size_t total = 0;
   int len;
   if (!EVP_DecryptUpdate(&tls_ctx->cipher_ctx, out, &len, in, (int)in_len)) {
     return 0;
   }
   total += len;
   if (!EVP_DecryptFinal_ex(&tls_ctx->cipher_ctx, out + total, &len)) {
     return 0;
   }
   total += len;
   assert(total == in_len);

   /* Remove CBC padding. Code from here on is timing-sensitive with respect to
    * |padding_ok| and |data_plus_mac_len| for CBC ciphers. */
   int padding_ok;
   unsigned data_plus_mac_len, data_len;
   if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE) {
     padding_ok = EVP_tls_cbc_remove_padding(
         &data_plus_mac_len, out, total,
         EVP_CIPHER_CTX_block_size(&tls_ctx->cipher_ctx),
         (unsigned)HMAC_size(&tls_ctx->hmac_ctx));
     /* Publicly invalid. This can be rejected in non-constant time. */
     if (padding_ok == 0) {
       OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
       return 0;
     }
   } else {
     padding_ok = 1;
     data_plus_mac_len = total;
     /* |data_plus_mac_len| = |total| = |in_len| at this point. |in_len| has
      * already been checked against the MAC size at the top of the function. */
     assert(data_plus_mac_len >= HMAC_size(&tls_ctx->hmac_ctx));
   }
   data_len = data_plus_mac_len - HMAC_size(&tls_ctx->hmac_ctx);

   /* At this point, |padding_ok| is 1 or -1. If 1, the padding is valid and the
    * first |data_plus_mac_size| bytes after |out| are the plaintext and
    * MAC. Either way, |data_plus_mac_size| is large enough to extract a MAC. */

   /* To allow for CBC mode which changes cipher length, |ad| doesn't include the
    * length for legacy ciphers. */
   uint8_t ad_fixed[13];
   memcpy(ad_fixed, ad, 11);
   ad_fixed[11] = (uint8_t)(data_len >> 8);
   ad_fixed[12] = (uint8_t)(data_len & 0xff);
   ad_len += 2;

   /* Compute the MAC and extract the one in the record. */
   uint8_t mac[EVP_MAX_MD_SIZE];
   size_t mac_len;
   uint8_t record_mac_tmp[EVP_MAX_MD_SIZE];
   uint8_t *record_mac;
   if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
       EVP_tls_cbc_record_digest_supported(tls_ctx->hmac_ctx.md)) {
     if (!EVP_tls_cbc_digest_record(tls_ctx->hmac_ctx.md, mac, &mac_len,
                                    ad_fixed, out, data_plus_mac_len, total,
                                    tls_ctx->mac_key, tls_ctx->mac_key_len)) {
       OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
       return 0;
     }
     assert(mac_len == HMAC_size(&tls_ctx->hmac_ctx));

     record_mac = record_mac_tmp;
     EVP_tls_cbc_copy_mac(record_mac, mac_len, out, data_plus_mac_len, total);
   } else {
     /* We should support the constant-time path for all CBC-mode ciphers
      * implemented. */
     assert(EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) != EVP_CIPH_CBC_MODE);

     HMAC_CTX hmac_ctx;
     HMAC_CTX_init(&hmac_ctx);
     unsigned mac_len_u;
     if (!HMAC_CTX_copy_ex(&hmac_ctx, &tls_ctx->hmac_ctx) ||
         !HMAC_Update(&hmac_ctx, ad_fixed, ad_len) ||
         !HMAC_Update(&hmac_ctx, out, data_len) ||
         !HMAC_Final(&hmac_ctx, mac, &mac_len_u)) {
       HMAC_CTX_cleanup(&hmac_ctx);
       return 0;
     }
     mac_len = mac_len_u;
     HMAC_CTX_cleanup(&hmac_ctx);

     assert(mac_len == HMAC_size(&tls_ctx->hmac_ctx));
     record_mac = &out[data_len];
   }

   /* Perform the MAC check and the padding check in constant-time. It should be
    * safe to simply perform the padding check first, but it would not be under a
    * different choice of MAC location on padding failure. See
    * EVP_tls_cbc_remove_padding. */
   unsigned good = constant_time_eq_int(CRYPTO_memcmp(record_mac, mac, mac_len),
                                        0);
   good &= constant_time_eq_int(padding_ok, 1);
   if (!good) {
     OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
     return 0;
   }

   /* End of timing-sensitive code. */

   *out_len = data_len;
   return 1;
 }

 static int aead_rc4_sha1_tls_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
                                   size_t key_len, size_t tag_len,
                                   enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_rc4(), EVP_sha1(),
                        0);
 }

 static int aead_aes_128_cbc_sha1_tls_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
                                           size_t key_len, size_t tag_len,
                                           enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_128_cbc(),
                        EVP_sha1(), 0);
 }

 static int aead_aes_128_cbc_sha1_tls_implicit_iv_init(
     EVP_AEAD_CTX *ctx, const uint8_t *key, size_t key_len, size_t tag_len,
     enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_128_cbc(),
                        EVP_sha1(), 1);
 }

 static int aead_aes_128_cbc_sha256_tls_init(EVP_AEAD_CTX *ctx,
                                             const uint8_t *key, size_t key_len,
                                             size_t tag_len,
                                             enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_128_cbc(),
                        EVP_sha256(), 0);
 }

 static int aead_aes_256_cbc_sha1_tls_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
                                           size_t key_len, size_t tag_len,
                                           enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_256_cbc(),
                        EVP_sha1(), 0);
 }

 static int aead_aes_256_cbc_sha1_tls_implicit_iv_init(
     EVP_AEAD_CTX *ctx, const uint8_t *key, size_t key_len, size_t tag_len,
     enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_256_cbc(),
                        EVP_sha1(), 1);
 }

 static int aead_aes_256_cbc_sha256_tls_init(EVP_AEAD_CTX *ctx,
                                             const uint8_t *key, size_t key_len,
                                             size_t tag_len,
                                             enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_256_cbc(),
                        EVP_sha256(), 0);
 }

 static int aead_aes_256_cbc_sha384_tls_init(EVP_AEAD_CTX *ctx,
                                             const uint8_t *key, size_t key_len,
                                             size_t tag_len,
                                             enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_256_cbc(),
                        EVP_sha384(), 0);
 }

 static int aead_des_ede3_cbc_sha1_tls_init(EVP_AEAD_CTX *ctx,
                                            const uint8_t *key, size_t key_len,
                                            size_t tag_len,
                                            enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_des_ede3_cbc(),
                        EVP_sha1(), 0);
 }

 static int aead_des_ede3_cbc_sha1_tls_implicit_iv_init(
     EVP_AEAD_CTX *ctx, const uint8_t *key, size_t key_len, size_t tag_len,
     enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_des_ede3_cbc(),
                        EVP_sha1(), 1);
 }

 static int aead_rc4_sha1_tls_get_rc4_state(const EVP_AEAD_CTX *ctx,
                                            const RC4_KEY **out_key) {
   const AEAD_TLS_CTX *tls_ctx = (AEAD_TLS_CTX*) ctx->aead_state;
   if (EVP_CIPHER_CTX_cipher(&tls_ctx->cipher_ctx) != EVP_rc4()) {
     return 0;
   }

   *out_key = (const RC4_KEY*) tls_ctx->cipher_ctx.cipher_data;
   return 1;
 }

 static int aead_null_sha1_tls_init(EVP_AEAD_CTX *ctx, const uint8_t *key,
                                    size_t key_len, size_t tag_len,
                                    enum evp_aead_direction_t dir) {
   return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_enc_null(),
                        EVP_sha1(), 1 /* implicit iv */);
 }

 static const EVP_AEAD aead_rc4_sha1_tls = {
     SHA_DIGEST_LENGTH + 16, /* key len (SHA1 + RC4) */
     0,                      /* nonce len */
     SHA_DIGEST_LENGTH,      /* overhead */
     SHA_DIGEST_LENGTH,      /* max tag length */
     NULL, /* init */
     aead_rc4_sha1_tls_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     aead_rc4_sha1_tls_get_rc4_state, /* get_rc4_state */
 };

 static const EVP_AEAD aead_aes_128_cbc_sha1_tls = {
     SHA_DIGEST_LENGTH + 16, /* key len (SHA1 + AES128) */
     16,                     /* nonce len (IV) */
     16 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
     SHA_DIGEST_LENGTH,      /* max tag length */
     NULL, /* init */
     aead_aes_128_cbc_sha1_tls_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                   /* get_rc4_state */
 };

 static const EVP_AEAD aead_aes_128_cbc_sha1_tls_implicit_iv = {
     SHA_DIGEST_LENGTH + 16 + 16, /* key len (SHA1 + AES128 + IV) */
     0,                           /* nonce len */
     16 + SHA_DIGEST_LENGTH,      /* overhead (padding + SHA1) */
     SHA_DIGEST_LENGTH,           /* max tag length */
     NULL, /* init */
     aead_aes_128_cbc_sha1_tls_implicit_iv_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                        /* get_rc4_state */
 };

 static const EVP_AEAD aead_aes_128_cbc_sha256_tls = {
     SHA256_DIGEST_LENGTH + 16, /* key len (SHA256 + AES128) */
     16,                        /* nonce len (IV) */
     16 + SHA256_DIGEST_LENGTH, /* overhead (padding + SHA256) */
     SHA256_DIGEST_LENGTH,      /* max tag length */
     NULL, /* init */
     aead_aes_128_cbc_sha256_tls_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                      /* get_rc4_state */
 };

 static const EVP_AEAD aead_aes_256_cbc_sha1_tls = {
     SHA_DIGEST_LENGTH + 32, /* key len (SHA1 + AES256) */
     16,                     /* nonce len (IV) */
     16 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
     SHA_DIGEST_LENGTH,      /* max tag length */
     NULL, /* init */
     aead_aes_256_cbc_sha1_tls_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                   /* get_rc4_state */
 };

 static const EVP_AEAD aead_aes_256_cbc_sha1_tls_implicit_iv = {
     SHA_DIGEST_LENGTH + 32 + 16, /* key len (SHA1 + AES256 + IV) */
     0,                           /* nonce len */
     16 + SHA_DIGEST_LENGTH,      /* overhead (padding + SHA1) */
     SHA_DIGEST_LENGTH,           /* max tag length */
     NULL, /* init */
     aead_aes_256_cbc_sha1_tls_implicit_iv_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                        /* get_rc4_state */
 };

 static const EVP_AEAD aead_aes_256_cbc_sha256_tls = {
     SHA256_DIGEST_LENGTH + 32, /* key len (SHA256 + AES256) */
     16,                        /* nonce len (IV) */
     16 + SHA256_DIGEST_LENGTH, /* overhead (padding + SHA256) */
     SHA256_DIGEST_LENGTH,      /* max tag length */
     NULL, /* init */
     aead_aes_256_cbc_sha256_tls_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                      /* get_rc4_state */
 };

 static const EVP_AEAD aead_aes_256_cbc_sha384_tls = {
     SHA384_DIGEST_LENGTH + 32, /* key len (SHA384 + AES256) */
     16,                        /* nonce len (IV) */
     16 + SHA384_DIGEST_LENGTH, /* overhead (padding + SHA384) */
     SHA384_DIGEST_LENGTH,      /* max tag length */
     NULL, /* init */
     aead_aes_256_cbc_sha384_tls_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                      /* get_rc4_state */
 };

 static const EVP_AEAD aead_des_ede3_cbc_sha1_tls = {
     SHA_DIGEST_LENGTH + 24, /* key len (SHA1 + 3DES) */
     8,                      /* nonce len (IV) */
     8 + SHA_DIGEST_LENGTH,  /* overhead (padding + SHA1) */
     SHA_DIGEST_LENGTH,      /* max tag length */
     NULL, /* init */
     aead_des_ede3_cbc_sha1_tls_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                   /* get_rc4_state */
 };

 static const EVP_AEAD aead_des_ede3_cbc_sha1_tls_implicit_iv = {
     SHA_DIGEST_LENGTH + 24 + 8, /* key len (SHA1 + 3DES + IV) */
     0,                          /* nonce len */
     8 + SHA_DIGEST_LENGTH,      /* overhead (padding + SHA1) */
     SHA_DIGEST_LENGTH,          /* max tag length */
     NULL, /* init */
     aead_des_ede3_cbc_sha1_tls_implicit_iv_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                       /* get_rc4_state */
 };

 static const EVP_AEAD aead_null_sha1_tls = {
     SHA_DIGEST_LENGTH,          /* key len */
     0,                          /* nonce len */
     SHA_DIGEST_LENGTH,          /* overhead (SHA1) */
     SHA_DIGEST_LENGTH,          /* max tag length */
     NULL,                       /* init */
     aead_null_sha1_tls_init,
     aead_tls_cleanup,
     aead_tls_seal,
     aead_tls_open,
     NULL,                       /* get_rc4_state */
 };

 const EVP_AEAD *EVP_aead_rc4_sha1_tls(void) { return &aead_rc4_sha1_tls; }

 const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls(void) {
   return &aead_aes_128_cbc_sha1_tls;
 }

 const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls_implicit_iv(void) {
   return &aead_aes_128_cbc_sha1_tls_implicit_iv;
 }

 const EVP_AEAD *EVP_aead_aes_128_cbc_sha256_tls(void) {
   return &aead_aes_128_cbc_sha256_tls;
 }

 const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls(void) {
   return &aead_aes_256_cbc_sha1_tls;
 }

 const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls_implicit_iv(void) {
   return &aead_aes_256_cbc_sha1_tls_implicit_iv;
 }

 const EVP_AEAD *EVP_aead_aes_256_cbc_sha256_tls(void) {
   return &aead_aes_256_cbc_sha256_tls;
 }

 const EVP_AEAD *EVP_aead_aes_256_cbc_sha384_tls(void) {
   return &aead_aes_256_cbc_sha384_tls;
 }

 const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls(void) {
   return &aead_des_ede3_cbc_sha1_tls;
 }

 const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls_implicit_iv(void) {
   return &aead_des_ede3_cbc_sha1_tls_implicit_iv;
 }

 const EVP_AEAD *EVP_aead_null_sha1_tls(void) { return &aead_null_sha1_tls; }
	/* Copyright (c) 2014, Google Inc.
	*
	* Permission to use, copy, modify, and/or distribute this software for any
	* purpose with or without fee is hereby granted, provided that the above
	* copyright notice and this permission notice appear in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
	* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
	* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
	* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

	#include <assert.h>
	#include <limits.h>
	#include <string.h>

	#include <openssl/aead.h>
	#include <openssl/cipher.h>
	#include <openssl/err.h>
	#include <openssl/hmac.h>
	#include <openssl/mem.h>
	#include <openssl/sha.h>
	#include <openssl/type_check.h>

	#include "../crypto/internal.h"
	#include "internal.h"


	typedef struct {
	EVP_CIPHER_CTX cipher_ctx;
	HMAC_CTX hmac_ctx;
	/* mac_key is the portion of the key used for the MAC. It is retained
	* separately for the constant-time CBC code. */
	uint8_t mac_key[EVP_MAX_MD_SIZE];
	uint8_t mac_key_len;
	/* implicit_iv is one iff this is a pre-TLS-1.1 CBC cipher without an explicit
	* IV. */
	char implicit_iv;
	} AEAD_TLS_CTX;

	OPENSSL_COMPILE_ASSERT(EVP_MAX_MD_SIZE < 256, mac_key_len_fits_in_uint8_t);

	static void aead_tls_cleanup(EVP_AEAD_CTX *ctx) {
	AEAD_TLS_CTX tls_ctx = (AEAD_TLS_CTX )ctx->aead_state;
	EVP_CIPHER_CTX_cleanup(&tls_ctx->cipher_ctx);
	HMAC_CTX_cleanup(&tls_ctx->hmac_ctx);
	OPENSSL_cleanse(&tls_ctx->mac_key, sizeof(tls_ctx->mac_key));
	OPENSSL_free(tls_ctx);
	ctx->aead_state = NULL;
	}

	static int aead_tls_init(EVP_AEAD_CTX ctx, const uint8_t key, size_t key_len,
	size_t tag_len, enum evp_aead_direction_t dir,
	const EVP_CIPHER cipher, const EVP_MD md,
	char implicit_iv) {
	if (tag_len != EVP_AEAD_DEFAULT_TAG_LENGTH &&
	tag_len != EVP_MD_size(md)) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_UNSUPPORTED_TAG_SIZE);
	return 0;
	}

	if (key_len != EVP_AEAD_key_length(ctx->aead)) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_KEY_LENGTH);
	return 0;
	}

	size_t mac_key_len = EVP_MD_size(md);
	size_t enc_key_len = EVP_CIPHER_key_length(cipher);
	assert(mac_key_len + enc_key_len +
	(implicit_iv ? EVP_CIPHER_iv_length(cipher) : 0) == key_len);
	/* Although EVP_rc4() is a variable-length cipher, the default key size is
	* correct for TLS. */

	AEAD_TLS_CTX *tls_ctx = OPENSSL_malloc(sizeof(AEAD_TLS_CTX));
	if (tls_ctx == NULL) {
	OPENSSL_PUT_ERROR(CIPHER, ERR_R_MALLOC_FAILURE);
	return 0;
	}
	EVP_CIPHER_CTX_init(&tls_ctx->cipher_ctx);
	HMAC_CTX_init(&tls_ctx->hmac_ctx);
	assert(mac_key_len <= EVP_MAX_MD_SIZE);
	memcpy(tls_ctx->mac_key, key, mac_key_len);
	tls_ctx->mac_key_len = (uint8_t)mac_key_len;
	tls_ctx->implicit_iv = implicit_iv;

	ctx->aead_state = tls_ctx;
	if (!EVP_CipherInit_ex(&tls_ctx->cipher_ctx, cipher, NULL, &key[mac_key_len],
	implicit_iv ? &key[mac_key_len + enc_key_len] : NULL,
	dir == evp_aead_seal) \|\|
	!HMAC_Init_ex(&tls_ctx->hmac_ctx, key, mac_key_len, md, NULL)) {
	aead_tls_cleanup(ctx);
	ctx->aead_state = NULL;
	return 0;
	}
	EVP_CIPHER_CTX_set_padding(&tls_ctx->cipher_ctx, 0);

	return 1;
	}

	static int aead_tls_seal(const EVP_AEAD_CTX ctx, uint8_t out,
	size_t *out_len, size_t max_out_len,
	const uint8_t *nonce, size_t nonce_len,
	const uint8_t *in, size_t in_len,
	const uint8_t *ad, size_t ad_len) {
	AEAD_TLS_CTX tls_ctx = (AEAD_TLS_CTX )ctx->aead_state;
	size_t total = 0;

	if (!tls_ctx->cipher_ctx.encrypt) {
	/* Unlike a normal AEAD, a TLS AEAD may only be used in one direction. */
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_OPERATION);
	return 0;

	}

	if (in_len + EVP_AEAD_max_overhead(ctx->aead) < in_len \|\|
	in_len > INT_MAX) {
	/* EVP_CIPHER takes int as input. */
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
	return 0;
	}

	if (max_out_len < in_len + EVP_AEAD_max_overhead(ctx->aead)) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
	return 0;
	}

	if (nonce_len != EVP_AEAD_nonce_length(ctx->aead)) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_NONCE_SIZE);
	return 0;
	}

	if (ad_len != 13 - 2 /* length bytes */) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_AD_SIZE);
	return 0;
	}

	/* To allow for CBC mode which changes cipher length, \|ad\| doesn't include the
	* length for legacy ciphers. */
	uint8_t ad_extra[2];
	ad_extra[0] = (uint8_t)(in_len >> 8);
	ad_extra[1] = (uint8_t)(in_len & 0xff);

	/* Compute the MAC. This must be first in case the operation is being done
	* in-place. */
	uint8_t mac[EVP_MAX_MD_SIZE];
	unsigned mac_len;
	HMAC_CTX hmac_ctx;
	HMAC_CTX_init(&hmac_ctx);
	if (!HMAC_CTX_copy_ex(&hmac_ctx, &tls_ctx->hmac_ctx) \|\|
	!HMAC_Update(&hmac_ctx, ad, ad_len) \|\|
	!HMAC_Update(&hmac_ctx, ad_extra, sizeof(ad_extra)) \|\|
	!HMAC_Update(&hmac_ctx, in, in_len) \|\|
	!HMAC_Final(&hmac_ctx, mac, &mac_len)) {
	HMAC_CTX_cleanup(&hmac_ctx);
	return 0;
	}
	HMAC_CTX_cleanup(&hmac_ctx);

	/* Configure the explicit IV. */
	if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
	!tls_ctx->implicit_iv &&
	!EVP_EncryptInit_ex(&tls_ctx->cipher_ctx, NULL, NULL, NULL, nonce)) {
	return 0;
	}

	/* Encrypt the input. */
	int len;
	if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out, &len, in,
	(int)in_len)) {
	return 0;
	}
	total = len;

	/* Feed the MAC into the cipher. */
	if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out + total, &len, mac,
	(int)mac_len)) {
	return 0;
	}
	total += len;

	unsigned block_size = EVP_CIPHER_CTX_block_size(&tls_ctx->cipher_ctx);
	if (block_size > 1) {
	assert(block_size <= 256);
	assert(EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE);

	/* Compute padding and feed that into the cipher. */
	uint8_t padding[256];
	unsigned padding_len = block_size - ((in_len + mac_len) % block_size);
	memset(padding, padding_len - 1, padding_len);
	if (!EVP_EncryptUpdate(&tls_ctx->cipher_ctx, out + total, &len, padding,
	(int)padding_len)) {
	return 0;
	}
	total += len;
	}

	if (!EVP_EncryptFinal_ex(&tls_ctx->cipher_ctx, out + total, &len)) {
	return 0;
	}
	total += len;

	*out_len = total;
	return 1;
	}

	static int aead_tls_open(const EVP_AEAD_CTX ctx, uint8_t out,
	size_t *out_len, size_t max_out_len,
	const uint8_t *nonce, size_t nonce_len,
	const uint8_t *in, size_t in_len,
	const uint8_t *ad, size_t ad_len) {
	AEAD_TLS_CTX tls_ctx = (AEAD_TLS_CTX )ctx->aead_state;

	if (tls_ctx->cipher_ctx.encrypt) {
	/* Unlike a normal AEAD, a TLS AEAD may only be used in one direction. */
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_OPERATION);
	return 0;

	}

	if (in_len < HMAC_size(&tls_ctx->hmac_ctx)) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
	return 0;
	}

	if (max_out_len < in_len) {
	/* This requires that the caller provide space for the MAC, even though it
	* will always be removed on return. */
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BUFFER_TOO_SMALL);
	return 0;
	}

	if (nonce_len != EVP_AEAD_nonce_length(ctx->aead)) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_NONCE_SIZE);
	return 0;
	}

	if (ad_len != 13 - 2 /* length bytes */) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_INVALID_AD_SIZE);
	return 0;
	}

	if (in_len > INT_MAX) {
	/* EVP_CIPHER takes int as input. */
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_TOO_LARGE);
	return 0;
	}

	/* Configure the explicit IV. */
	if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
	!tls_ctx->implicit_iv &&
	!EVP_DecryptInit_ex(&tls_ctx->cipher_ctx, NULL, NULL, NULL, nonce)) {
	return 0;
	}

	/* Decrypt to get the plaintext + MAC + padding. */
	size_t total = 0;
	int len;
	if (!EVP_DecryptUpdate(&tls_ctx->cipher_ctx, out, &len, in, (int)in_len)) {
	return 0;
	}
	total += len;
	if (!EVP_DecryptFinal_ex(&tls_ctx->cipher_ctx, out + total, &len)) {
	return 0;
	}
	total += len;
	assert(total == in_len);

	/* Remove CBC padding. Code from here on is timing-sensitive with respect to
	* \|padding_ok\| and \|data_plus_mac_len\| for CBC ciphers. */
	int padding_ok;
	unsigned data_plus_mac_len, data_len;
	if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE) {
	padding_ok = EVP_tls_cbc_remove_padding(
	&data_plus_mac_len, out, total,
	EVP_CIPHER_CTX_block_size(&tls_ctx->cipher_ctx),
	(unsigned)HMAC_size(&tls_ctx->hmac_ctx));
	/* Publicly invalid. This can be rejected in non-constant time. */
	if (padding_ok == 0) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
	return 0;
	}
	} else {
	padding_ok = 1;
	data_plus_mac_len = total;
	/* \|data_plus_mac_len\| = \|total\| = \|in_len\| at this point. \|in_len\| has
	* already been checked against the MAC size at the top of the function. */
	assert(data_plus_mac_len >= HMAC_size(&tls_ctx->hmac_ctx));
	}
	data_len = data_plus_mac_len - HMAC_size(&tls_ctx->hmac_ctx);

	/* At this point, \|padding_ok\| is 1 or -1. If 1, the padding is valid and the
	* first \|data_plus_mac_size\| bytes after \|out\| are the plaintext and
	* MAC. Either way, \|data_plus_mac_size\| is large enough to extract a MAC. */

	/* To allow for CBC mode which changes cipher length, \|ad\| doesn't include the
	* length for legacy ciphers. */
	uint8_t ad_fixed[13];
	memcpy(ad_fixed, ad, 11);
	ad_fixed[11] = (uint8_t)(data_len >> 8);
	ad_fixed[12] = (uint8_t)(data_len & 0xff);
	ad_len += 2;

	/* Compute the MAC and extract the one in the record. */
	uint8_t mac[EVP_MAX_MD_SIZE];
	size_t mac_len;
	uint8_t record_mac_tmp[EVP_MAX_MD_SIZE];
	uint8_t *record_mac;
	if (EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) == EVP_CIPH_CBC_MODE &&
	EVP_tls_cbc_record_digest_supported(tls_ctx->hmac_ctx.md)) {
	if (!EVP_tls_cbc_digest_record(tls_ctx->hmac_ctx.md, mac, &mac_len,
	ad_fixed, out, data_plus_mac_len, total,
	tls_ctx->mac_key, tls_ctx->mac_key_len)) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
	return 0;
	}
	assert(mac_len == HMAC_size(&tls_ctx->hmac_ctx));

	record_mac = record_mac_tmp;
	EVP_tls_cbc_copy_mac(record_mac, mac_len, out, data_plus_mac_len, total);
	} else {
	/* We should support the constant-time path for all CBC-mode ciphers
	* implemented. */
	assert(EVP_CIPHER_CTX_mode(&tls_ctx->cipher_ctx) != EVP_CIPH_CBC_MODE);

	HMAC_CTX hmac_ctx;
	HMAC_CTX_init(&hmac_ctx);
	unsigned mac_len_u;
	if (!HMAC_CTX_copy_ex(&hmac_ctx, &tls_ctx->hmac_ctx) \|\|
	!HMAC_Update(&hmac_ctx, ad_fixed, ad_len) \|\|
	!HMAC_Update(&hmac_ctx, out, data_len) \|\|
	!HMAC_Final(&hmac_ctx, mac, &mac_len_u)) {
	HMAC_CTX_cleanup(&hmac_ctx);
	return 0;
	}
	mac_len = mac_len_u;
	HMAC_CTX_cleanup(&hmac_ctx);

	assert(mac_len == HMAC_size(&tls_ctx->hmac_ctx));
	record_mac = &out[data_len];
	}

	/* Perform the MAC check and the padding check in constant-time. It should be
	* safe to simply perform the padding check first, but it would not be under a
	* different choice of MAC location on padding failure. See
	* EVP_tls_cbc_remove_padding. */
	unsigned good = constant_time_eq_int(CRYPTO_memcmp(record_mac, mac, mac_len),
	0);
	good &= constant_time_eq_int(padding_ok, 1);
	if (!good) {
	OPENSSL_PUT_ERROR(CIPHER, CIPHER_R_BAD_DECRYPT);
	return 0;
	}

	/* End of timing-sensitive code. */

	*out_len = data_len;
	return 1;
	}

	static int aead_rc4_sha1_tls_init(EVP_AEAD_CTX ctx, const uint8_t key,
	size_t key_len, size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_rc4(), EVP_sha1(),
	0);
	}

	static int aead_aes_128_cbc_sha1_tls_init(EVP_AEAD_CTX ctx, const uint8_t key,
	size_t key_len, size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_128_cbc(),
	EVP_sha1(), 0);
	}

	static int aead_aes_128_cbc_sha1_tls_implicit_iv_init(
	EVP_AEAD_CTX ctx, const uint8_t key, size_t key_len, size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_128_cbc(),
	EVP_sha1(), 1);
	}

	static int aead_aes_128_cbc_sha256_tls_init(EVP_AEAD_CTX *ctx,
	const uint8_t *key, size_t key_len,
	size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_128_cbc(),
	EVP_sha256(), 0);
	}

	static int aead_aes_256_cbc_sha1_tls_init(EVP_AEAD_CTX ctx, const uint8_t key,
	size_t key_len, size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_256_cbc(),
	EVP_sha1(), 0);
	}

	static int aead_aes_256_cbc_sha1_tls_implicit_iv_init(
	EVP_AEAD_CTX ctx, const uint8_t key, size_t key_len, size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_256_cbc(),
	EVP_sha1(), 1);
	}

	static int aead_aes_256_cbc_sha256_tls_init(EVP_AEAD_CTX *ctx,
	const uint8_t *key, size_t key_len,
	size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_256_cbc(),
	EVP_sha256(), 0);
	}

	static int aead_aes_256_cbc_sha384_tls_init(EVP_AEAD_CTX *ctx,
	const uint8_t *key, size_t key_len,
	size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_aes_256_cbc(),
	EVP_sha384(), 0);
	}

	static int aead_des_ede3_cbc_sha1_tls_init(EVP_AEAD_CTX *ctx,
	const uint8_t *key, size_t key_len,
	size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_des_ede3_cbc(),
	EVP_sha1(), 0);
	}

	static int aead_des_ede3_cbc_sha1_tls_implicit_iv_init(
	EVP_AEAD_CTX ctx, const uint8_t key, size_t key_len, size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_des_ede3_cbc(),
	EVP_sha1(), 1);
	}

	static int aead_rc4_sha1_tls_get_rc4_state(const EVP_AEAD_CTX *ctx,
	const RC4_KEY **out_key) {
	const AEAD_TLS_CTX tls_ctx = (AEAD_TLS_CTX) ctx->aead_state;
	if (EVP_CIPHER_CTX_cipher(&tls_ctx->cipher_ctx) != EVP_rc4()) {
	return 0;
	}

	out_key = (const RC4_KEY) tls_ctx->cipher_ctx.cipher_data;
	return 1;
	}

	static int aead_null_sha1_tls_init(EVP_AEAD_CTX ctx, const uint8_t key,
	size_t key_len, size_t tag_len,
	enum evp_aead_direction_t dir) {
	return aead_tls_init(ctx, key, key_len, tag_len, dir, EVP_enc_null(),
	EVP_sha1(), 1 /* implicit iv */);
	}

	static const EVP_AEAD aead_rc4_sha1_tls = {
	SHA_DIGEST_LENGTH + 16, /* key len (SHA1 + RC4) */
	0, /* nonce len */
	SHA_DIGEST_LENGTH, /* overhead */
	SHA_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_rc4_sha1_tls_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	aead_rc4_sha1_tls_get_rc4_state, /* get_rc4_state */
	};

	static const EVP_AEAD aead_aes_128_cbc_sha1_tls = {
	SHA_DIGEST_LENGTH + 16, /* key len (SHA1 + AES128) */
	16, /* nonce len (IV) */
	16 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
	SHA_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_aes_128_cbc_sha1_tls_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_aes_128_cbc_sha1_tls_implicit_iv = {
	SHA_DIGEST_LENGTH + 16 + 16, /* key len (SHA1 + AES128 + IV) */
	0, /* nonce len */
	16 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
	SHA_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_aes_128_cbc_sha1_tls_implicit_iv_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_aes_128_cbc_sha256_tls = {
	SHA256_DIGEST_LENGTH + 16, /* key len (SHA256 + AES128) */
	16, /* nonce len (IV) */
	16 + SHA256_DIGEST_LENGTH, /* overhead (padding + SHA256) */
	SHA256_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_aes_128_cbc_sha256_tls_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_aes_256_cbc_sha1_tls = {
	SHA_DIGEST_LENGTH + 32, /* key len (SHA1 + AES256) */
	16, /* nonce len (IV) */
	16 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
	SHA_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_aes_256_cbc_sha1_tls_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_aes_256_cbc_sha1_tls_implicit_iv = {
	SHA_DIGEST_LENGTH + 32 + 16, /* key len (SHA1 + AES256 + IV) */
	0, /* nonce len */
	16 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
	SHA_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_aes_256_cbc_sha1_tls_implicit_iv_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_aes_256_cbc_sha256_tls = {
	SHA256_DIGEST_LENGTH + 32, /* key len (SHA256 + AES256) */
	16, /* nonce len (IV) */
	16 + SHA256_DIGEST_LENGTH, /* overhead (padding + SHA256) */
	SHA256_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_aes_256_cbc_sha256_tls_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_aes_256_cbc_sha384_tls = {
	SHA384_DIGEST_LENGTH + 32, /* key len (SHA384 + AES256) */
	16, /* nonce len (IV) */
	16 + SHA384_DIGEST_LENGTH, /* overhead (padding + SHA384) */
	SHA384_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_aes_256_cbc_sha384_tls_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_des_ede3_cbc_sha1_tls = {
	SHA_DIGEST_LENGTH + 24, /* key len (SHA1 + 3DES) */
	8, /* nonce len (IV) */
	8 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
	SHA_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_des_ede3_cbc_sha1_tls_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_des_ede3_cbc_sha1_tls_implicit_iv = {
	SHA_DIGEST_LENGTH + 24 + 8, /* key len (SHA1 + 3DES + IV) */
	0, /* nonce len */
	8 + SHA_DIGEST_LENGTH, /* overhead (padding + SHA1) */
	SHA_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_des_ede3_cbc_sha1_tls_implicit_iv_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	static const EVP_AEAD aead_null_sha1_tls = {
	SHA_DIGEST_LENGTH, /* key len */
	0, /* nonce len */
	SHA_DIGEST_LENGTH, /* overhead (SHA1) */
	SHA_DIGEST_LENGTH, /* max tag length */
	NULL, /* init */
	aead_null_sha1_tls_init,
	aead_tls_cleanup,
	aead_tls_seal,
	aead_tls_open,
	NULL, /* get_rc4_state */
	};

	const EVP_AEAD *EVP_aead_rc4_sha1_tls(void) { return &aead_rc4_sha1_tls; }

	const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls(void) {
	return &aead_aes_128_cbc_sha1_tls;
	}

	const EVP_AEAD *EVP_aead_aes_128_cbc_sha1_tls_implicit_iv(void) {
	return &aead_aes_128_cbc_sha1_tls_implicit_iv;
	}

	const EVP_AEAD *EVP_aead_aes_128_cbc_sha256_tls(void) {
	return &aead_aes_128_cbc_sha256_tls;
	}

	const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls(void) {
	return &aead_aes_256_cbc_sha1_tls;
	}

	const EVP_AEAD *EVP_aead_aes_256_cbc_sha1_tls_implicit_iv(void) {
	return &aead_aes_256_cbc_sha1_tls_implicit_iv;
	}

	const EVP_AEAD *EVP_aead_aes_256_cbc_sha256_tls(void) {
	return &aead_aes_256_cbc_sha256_tls;
	}

	const EVP_AEAD *EVP_aead_aes_256_cbc_sha384_tls(void) {
	return &aead_aes_256_cbc_sha384_tls;
	}

	const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls(void) {
	return &aead_des_ede3_cbc_sha1_tls;
	}

	const EVP_AEAD *EVP_aead_des_ede3_cbc_sha1_tls_implicit_iv(void) {
	return &aead_des_ede3_cbc_sha1_tls_implicit_iv;
	}

	const EVP_AEAD *EVP_aead_null_sha1_tls(void) { return &aead_null_sha1_tls; }