common/mbedtls/ssl_ticket.h

   1 /**
   2  * \file ssl_ticket.h
   3  *
   4  * \brief TLS server ticket callbacks implementation
   5  */
   6 /*
   7  *  Copyright The Mbed TLS Contributors
   8  *  SPDX-License-Identifier: Apache-2.0
   9  *
  10  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
  11  *  not use this file except in compliance with the License.
  12  *  You may obtain a copy of the License at
  13  *
  14  *  http://www.apache.org/licenses/LICENSE-2.0
  15  *
  16  *  Unless required by applicable law or agreed to in writing, software
  17  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  18  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  19  *  See the License for the specific language governing permissions and
  20  *  limitations under the License.
  21  */
  22 #ifndef MBEDTLS_SSL_TICKET_H
  23 #define MBEDTLS_SSL_TICKET_H
  24
  25 #if !defined(MBEDTLS_CONFIG_FILE)
  26 #include "mbedtls/config.h"
  27 #else
  28 #include MBEDTLS_CONFIG_FILE
  29 #endif
  30
  31 /*
  32  * This implementation of the session ticket callbacks includes key
  33  * management, rotating the keys periodically in order to preserve forward
  34  * secrecy, when MBEDTLS_HAVE_TIME is defined.
  35  */
  36
  37 #include "mbedtls/ssl.h"
  38 #include "mbedtls/cipher.h"
  39
  40 #if defined(MBEDTLS_THREADING_C)
  41 #include "mbedtls/threading.h"
  42 #endif
  43
  44 #ifdef __cplusplus
  45 extern "C" {
  46 #endif
  47
  48 /**
  49  * \brief   Information for session ticket protection
  50  */
  51 typedef struct mbedtls_ssl_ticket_key {
  52     unsigned char name[4];          /*!< random key identifier              */
  53     uint32_t generation_time;       /*!< key generation timestamp (seconds) */
  54     mbedtls_cipher_context_t ctx;   /*!< context for auth enc/decryption    */
  55 }
  56 mbedtls_ssl_ticket_key;
  57
  58 /**
  59  * \brief   Context for session ticket handling functions
  60  */
  61 typedef struct mbedtls_ssl_ticket_context {
  62     mbedtls_ssl_ticket_key keys[2]; /*!< ticket protection keys             */
  63     unsigned char active;           /*!< index of the currently active key  */
  64
  65     uint32_t ticket_lifetime;       /*!< lifetime of tickets in seconds     */
  66
  67     /** Callback for getting (pseudo-)random numbers                        */
  68     int (*f_rng)(void *, unsigned char *, size_t);
  69     void *p_rng;                    /*!< context for the RNG function       */
  70
  71 #if defined(MBEDTLS_THREADING_C)
  72     mbedtls_threading_mutex_t mutex;
  73 #endif
  74 }
  75 mbedtls_ssl_ticket_context;
  76
  77 /**
  78  * \brief           Initialize a ticket context.
  79  *                  (Just make it ready for mbedtls_ssl_ticket_setup()
  80  *                  or mbedtls_ssl_ticket_free().)
  81  *
  82  * \param ctx       Context to be initialized
  83  */
  84 void mbedtls_ssl_ticket_init(mbedtls_ssl_ticket_context *ctx);
  85
  86 /**
  87  * \brief           Prepare context to be actually used
  88  *
  89  * \param ctx       Context to be set up
  90  * \param f_rng     RNG callback function
  91  * \param p_rng     RNG callback context
  92  * \param cipher    AEAD cipher to use for ticket protection.
  93  *                  Recommended value: MBEDTLS_CIPHER_AES_256_GCM.
  94  * \param lifetime  Tickets lifetime in seconds
  95  *                  Recommended value: 86400 (one day).
  96  *
  97  * \note            It is highly recommended to select a cipher that is at
  98  *                  least as strong as the the strongest ciphersuite
  99  *                  supported. Usually that means a 256-bit key.
 100  *
 101  * \note            The lifetime of the keys is twice the lifetime of tickets.
 102  *                  It is recommended to pick a reasonnable lifetime so as not
 103  *                  to negate the benefits of forward secrecy.
 104  *
 105  * \return          0 if successful,
 106  *                  or a specific MBEDTLS_ERR_XXX error code
 107  */
 108 int mbedtls_ssl_ticket_setup(mbedtls_ssl_ticket_context *ctx,
 109                              int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
 110                              mbedtls_cipher_type_t cipher,
 111                              uint32_t lifetime);
 112
 113 /**
 114  * \brief           Implementation of the ticket write callback
 115  *
 116  * \note            See \c mbedtls_ssl_ticket_write_t for description
 117  */
 118 mbedtls_ssl_ticket_write_t mbedtls_ssl_ticket_write;
 119
 120 /**
 121  * \brief           Implementation of the ticket parse callback
 122  *
 123  * \note            See \c mbedtls_ssl_ticket_parse_t for description
 124  */
 125 mbedtls_ssl_ticket_parse_t mbedtls_ssl_ticket_parse;
 126
 127 /**
 128  * \brief           Free a context's content and zeroize it.
 129  *
 130  * \param ctx       Context to be cleaned up
 131  */
 132 void mbedtls_ssl_ticket_free(mbedtls_ssl_ticket_context *ctx);
 133
 134 #ifdef __cplusplus
 135 }
 136 #endif
 137
 138 #endif /* ssl_ticket.h */