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_HAVE_TIME) 38 #include "mbedtls/platform_time.h" 39 #endif 40 41 #if defined(MBEDTLS_USE_PSA_CRYPTO) 42 #include "psa/crypto.h" 43 #endif 44 45 #if defined(MBEDTLS_THREADING_C) 46 #include "mbedtls/threading.h" 47 #endif 48 49 #ifdef __cplusplus 50 extern "C" { 51 #endif 52 53 #define MBEDTLS_SSL_TICKET_MAX_KEY_BYTES 32 /*!< Max supported key length in bytes */ 54 #define MBEDTLS_SSL_TICKET_KEY_NAME_BYTES 4 /*!< key name length in bytes */ 55 56 /** 57 * \brief Information for session ticket protection 58 */ 59 typedef struct mbedtls_ssl_ticket_key 60 { 61 unsigned char MBEDTLS_PRIVATE(name)[MBEDTLS_SSL_TICKET_KEY_NAME_BYTES]; 62 /*!< random key identifier */ 63 #if defined(MBEDTLS_HAVE_TIME) 64 mbedtls_time_t MBEDTLS_PRIVATE(generation_time); /*!< key generation timestamp (seconds) */ 65 #endif 66 #if !defined(MBEDTLS_USE_PSA_CRYPTO) 67 mbedtls_cipher_context_t MBEDTLS_PRIVATE(ctx); /*!< context for auth enc/decryption */ 68 #else 69 mbedtls_svc_key_id_t MBEDTLS_PRIVATE(key); /*!< key used for auth enc/decryption */ 70 psa_algorithm_t MBEDTLS_PRIVATE(alg); /*!< algorithm of auth enc/decryption */ 71 psa_key_type_t MBEDTLS_PRIVATE(key_type); /*!< key type */ 72 size_t MBEDTLS_PRIVATE(key_bits); /*!< key length in bits */ 73 #endif 74 } 75 mbedtls_ssl_ticket_key; 76 77 /** 78 * \brief Context for session ticket handling functions 79 */ 80 typedef struct mbedtls_ssl_ticket_context 81 { 82 mbedtls_ssl_ticket_key MBEDTLS_PRIVATE(keys)[2]; /*!< ticket protection keys */ 83 unsigned char MBEDTLS_PRIVATE(active); /*!< index of the currently active key */ 84 85 uint32_t MBEDTLS_PRIVATE(ticket_lifetime); /*!< lifetime of tickets in seconds */ 86 87 /** Callback for getting (pseudo-)random numbers */ 88 int (*MBEDTLS_PRIVATE(f_rng))(void *, unsigned char *, size_t); 89 void *MBEDTLS_PRIVATE(p_rng); /*!< context for the RNG function */ 90 91 #if defined(MBEDTLS_THREADING_C) 92 mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex); 93 #endif 94 } 95 mbedtls_ssl_ticket_context; 96 97 /** 98 * \brief Initialize a ticket context. 99 * (Just make it ready for mbedtls_ssl_ticket_setup() 100 * or mbedtls_ssl_ticket_free().) 101 * 102 * \param ctx Context to be initialized 103 */ 104 void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx ); 105 106 /** 107 * \brief Prepare context to be actually used 108 * 109 * \param ctx Context to be set up 110 * \param f_rng RNG callback function (mandatory) 111 * \param p_rng RNG callback context 112 * \param cipher AEAD cipher to use for ticket protection. 113 * Recommended value: MBEDTLS_CIPHER_AES_256_GCM. 114 * \param lifetime Tickets lifetime in seconds 115 * Recommended value: 86400 (one day). 116 * 117 * \note It is highly recommended to select a cipher that is at 118 * least as strong as the strongest ciphersuite 119 * supported. Usually that means a 256-bit key. 120 * 121 * \note The lifetime of the keys is twice the lifetime of tickets. 122 * It is recommended to pick a reasonable lifetime so as not 123 * to negate the benefits of forward secrecy. 124 * 125 * \return 0 if successful, 126 * or a specific MBEDTLS_ERR_XXX error code 127 */ 128 int mbedtls_ssl_ticket_setup( mbedtls_ssl_ticket_context *ctx, 129 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, 130 mbedtls_cipher_type_t cipher, 131 uint32_t lifetime ); 132 133 /** 134 * \brief Rotate session ticket encryption key to new specified key. 135 * Provides for external control of session ticket encryption 136 * key rotation, e.g. for synchronization between different 137 * machines. If this function is not used, or if not called 138 * before ticket lifetime expires, then a new session ticket 139 * encryption key is generated internally in order to avoid 140 * unbounded session ticket encryption key lifetimes. 141 * 142 * \param ctx Context to be set up 143 * \param name Session ticket encryption key name 144 * \param nlength Session ticket encryption key name length in bytes 145 * \param k Session ticket encryption key 146 * \param klength Session ticket encryption key length in bytes 147 * \param lifetime Tickets lifetime in seconds 148 * Recommended value: 86400 (one day). 149 * 150 * \note \c name and \c k are recommended to be cryptographically 151 * random data. 152 * 153 * \note \c nlength must match sizeof( ctx->name ) 154 * 155 * \note \c klength must be sufficient for use by cipher specified 156 * to \c mbedtls_ssl_ticket_setup 157 * 158 * \note The lifetime of the keys is twice the lifetime of tickets. 159 * It is recommended to pick a reasonable lifetime so as not 160 * to negate the benefits of forward secrecy. 161 * 162 * \return 0 if successful, 163 * or a specific MBEDTLS_ERR_XXX error code 164 */ 165 int mbedtls_ssl_ticket_rotate( mbedtls_ssl_ticket_context *ctx, 166 const unsigned char *name, size_t nlength, 167 const unsigned char *k, size_t klength, 168 uint32_t lifetime ); 169 170 /** 171 * \brief Implementation of the ticket write callback 172 * 173 * \note See \c mbedtls_ssl_ticket_write_t for description 174 */ 175 mbedtls_ssl_ticket_write_t mbedtls_ssl_ticket_write; 176 177 /** 178 * \brief Implementation of the ticket parse callback 179 * 180 * \note See \c mbedtls_ssl_ticket_parse_t for description 181 */ 182 mbedtls_ssl_ticket_parse_t mbedtls_ssl_ticket_parse; 183 184 /** 185 * \brief Free a context's content and zeroize it. 186 * 187 * \param ctx Context to be cleaned up 188 */ 189 void mbedtls_ssl_ticket_free( mbedtls_ssl_ticket_context *ctx ); 190 191 #ifdef __cplusplus 192 } 193 #endif 194 195 #endif /* ssl_ticket.h */ 196
