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