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 #include "mbedtls/private_access.h" 25 26 #include "mbedtls/build_info.h" 27 28 /* 29 * This implementation of the session ticket callbacks includes key 30 * management, rotating the keys periodically in order to preserve forward 31 * secrecy, when MBEDTLS_HAVE_TIME is defined. 32 */ 33 34 #include "mbedtls/ssl.h" 35 #include "mbedtls/cipher.h" 36 37 #if defined(MBEDTLS_THREADING_C) 38 #include "mbedtls/threading.h" 39 #endif 40 41 #ifdef __cplusplus 42 extern "C" { 43 #endif 44 45 /** 46 * \brief Information for session ticket protection 47 */ 48 typedef struct mbedtls_ssl_ticket_key 49 { 50 unsigned char MBEDTLS_PRIVATE(name)[4]; /*!< random key identifier */ 51 uint32_t MBEDTLS_PRIVATE(generation_time); /*!< key generation timestamp (seconds) */ 52 mbedtls_cipher_context_t MBEDTLS_PRIVATE(ctx); /*!< context for auth enc/decryption */ 53 } 54 mbedtls_ssl_ticket_key; 55 56 /** 57 * \brief Context for session ticket handling functions 58 */ 59 typedef struct mbedtls_ssl_ticket_context 60 { 61 mbedtls_ssl_ticket_key MBEDTLS_PRIVATE(keys)[2]; /*!< ticket protection keys */ 62 unsigned char MBEDTLS_PRIVATE(active); /*!< index of the currently active key */ 63 64 uint32_t MBEDTLS_PRIVATE(ticket_lifetime); /*!< lifetime of tickets in seconds */ 65 66 /** Callback for getting (pseudo-)random numbers */ 67 int (*MBEDTLS_PRIVATE(f_rng))(void *, unsigned char *, size_t); 68 void *MBEDTLS_PRIVATE(p_rng); /*!< context for the RNG function */ 69 70 #if defined(MBEDTLS_THREADING_C) 71 mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex); 72 #endif 73 } 74 mbedtls_ssl_ticket_context; 75 76 /** 77 * \brief Initialize a ticket context. 78 * (Just make it ready for mbedtls_ssl_ticket_setup() 79 * or mbedtls_ssl_ticket_free().) 80 * 81 * \param ctx Context to be initialized 82 */ 83 void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx ); 84 85 /** 86 * \brief Prepare context to be actually used 87 * 88 * \param ctx Context to be set up 89 * \param f_rng RNG callback function (mandatory) 90 * \param p_rng RNG callback context 91 * \param cipher AEAD cipher to use for ticket protection. 92 * Recommended value: MBEDTLS_CIPHER_AES_256_GCM. 93 * \param lifetime Tickets lifetime in seconds 94 * Recommended value: 86400 (one day). 95 * 96 * \note It is highly recommended to select a cipher that is at 97 * least as strong as the strongest ciphersuite 98 * supported. Usually that means a 256-bit key. 99 * 100 * \note The lifetime of the keys is twice the lifetime of tickets. 101 * It is recommended to pick a reasonnable lifetime so as not 102 * to negate the benefits of forward secrecy. 103 * 104 * \return 0 if successful, 105 * or a specific MBEDTLS_ERR_XXX error code 106 */ 107 int mbedtls_ssl_ticket_setup( mbedtls_ssl_ticket_context *ctx, 108 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, 109 mbedtls_cipher_type_t cipher, 110 uint32_t lifetime ); 111 112 /** 113 * \brief Implementation of the ticket write callback 114 * 115 * \note See \c mbedtls_ssl_ticket_write_t for description 116 */ 117 mbedtls_ssl_ticket_write_t mbedtls_ssl_ticket_write; 118 119 /** 120 * \brief Implementation of the ticket parse callback 121 * 122 * \note See \c mbedtls_ssl_ticket_parse_t for description 123 */ 124 mbedtls_ssl_ticket_parse_t mbedtls_ssl_ticket_parse; 125 126 /** 127 * \brief Free a context's content and zeroize it. 128 * 129 * \param ctx Context to be cleaned up 130 */ 131 void mbedtls_ssl_ticket_free( mbedtls_ssl_ticket_context *ctx ); 132 133 #ifdef __cplusplus 134 } 135 #endif 136 137 #endif /* ssl_ticket.h */ 138