/** * \file ssl_ticket.h * * \brief TLS server ticket callbacks implementation */ /* * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifndef MBEDTLS_SSL_TICKET_H #define MBEDTLS_SSL_TICKET_H #include "mbedtls/private_access.h" #include "mbedtls/build_info.h" /* * This implementation of the session ticket callbacks includes key * management, rotating the keys periodically in order to preserve forward * secrecy, when MBEDTLS_HAVE_TIME is defined. */ #include "mbedtls/ssl.h" #include "mbedtls/cipher.h" #if defined(MBEDTLS_HAVE_TIME) #include "mbedtls/platform_time.h" #endif #if defined(MBEDTLS_USE_PSA_CRYPTO) #include "psa/crypto.h" #endif #if defined(MBEDTLS_THREADING_C) #include "mbedtls/threading.h" #endif #ifdef __cplusplus extern "C" { #endif #define MBEDTLS_SSL_TICKET_MAX_KEY_BYTES 32 /*!< Max supported key length in bytes */ #define MBEDTLS_SSL_TICKET_KEY_NAME_BYTES 4 /*!< key name length in bytes */ /** * \brief Information for session ticket protection */ typedef struct mbedtls_ssl_ticket_key { unsigned char MBEDTLS_PRIVATE(name)[MBEDTLS_SSL_TICKET_KEY_NAME_BYTES]; /*!< random key identifier */ #if defined(MBEDTLS_HAVE_TIME) mbedtls_time_t MBEDTLS_PRIVATE(generation_time); /*!< key generation timestamp (seconds) */ #endif #if !defined(MBEDTLS_USE_PSA_CRYPTO) mbedtls_cipher_context_t MBEDTLS_PRIVATE(ctx); /*!< context for auth enc/decryption */ #else mbedtls_svc_key_id_t MBEDTLS_PRIVATE(key); /*!< key used for auth enc/decryption */ psa_algorithm_t MBEDTLS_PRIVATE(alg); /*!< algorithm of auth enc/decryption */ psa_key_type_t MBEDTLS_PRIVATE(key_type); /*!< key type */ size_t MBEDTLS_PRIVATE(key_bits); /*!< key length in bits */ #endif } mbedtls_ssl_ticket_key; /** * \brief Context for session ticket handling functions */ typedef struct mbedtls_ssl_ticket_context { mbedtls_ssl_ticket_key MBEDTLS_PRIVATE(keys)[2]; /*!< ticket protection keys */ unsigned char MBEDTLS_PRIVATE(active); /*!< index of the currently active key */ uint32_t MBEDTLS_PRIVATE(ticket_lifetime); /*!< lifetime of tickets in seconds */ /** Callback for getting (pseudo-)random numbers */ int (*MBEDTLS_PRIVATE(f_rng))(void *, unsigned char *, size_t); void *MBEDTLS_PRIVATE(p_rng); /*!< context for the RNG function */ #if defined(MBEDTLS_THREADING_C) mbedtls_threading_mutex_t MBEDTLS_PRIVATE(mutex); #endif } mbedtls_ssl_ticket_context; /** * \brief Initialize a ticket context. * (Just make it ready for mbedtls_ssl_ticket_setup() * or mbedtls_ssl_ticket_free().) * * \param ctx Context to be initialized */ void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx ); /** * \brief Prepare context to be actually used * * \param ctx Context to be set up * \param f_rng RNG callback function (mandatory) * \param p_rng RNG callback context * \param cipher AEAD cipher to use for ticket protection. * Recommended value: MBEDTLS_CIPHER_AES_256_GCM. * \param lifetime Tickets lifetime in seconds * Recommended value: 86400 (one day). * * \note It is highly recommended to select a cipher that is at * least as strong as the strongest ciphersuite * supported. Usually that means a 256-bit key. * * \note The lifetime of the keys is twice the lifetime of tickets. * It is recommended to pick a reasonable lifetime so as not * to negate the benefits of forward secrecy. * * \return 0 if successful, * or a specific MBEDTLS_ERR_XXX error code */ int mbedtls_ssl_ticket_setup( mbedtls_ssl_ticket_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, mbedtls_cipher_type_t cipher, uint32_t lifetime ); /** * \brief Rotate session ticket encryption key to new specified key. * Provides for external control of session ticket encryption * key rotation, e.g. for synchronization between different * machines. If this function is not used, or if not called * before ticket lifetime expires, then a new session ticket * encryption key is generated internally in order to avoid * unbounded session ticket encryption key lifetimes. * * \param ctx Context to be set up * \param name Session ticket encryption key name * \param nlength Session ticket encryption key name length in bytes * \param k Session ticket encryption key * \param klength Session ticket encryption key length in bytes * \param lifetime Tickets lifetime in seconds * Recommended value: 86400 (one day). * * \note \c name and \c k are recommended to be cryptographically * random data. * * \note \c nlength must match sizeof( ctx->name ) * * \note \c klength must be sufficient for use by cipher specified * to \c mbedtls_ssl_ticket_setup * * \note The lifetime of the keys is twice the lifetime of tickets. * It is recommended to pick a reasonable lifetime so as not * to negate the benefits of forward secrecy. * * \return 0 if successful, * or a specific MBEDTLS_ERR_XXX error code */ int mbedtls_ssl_ticket_rotate( mbedtls_ssl_ticket_context *ctx, const unsigned char *name, size_t nlength, const unsigned char *k, size_t klength, uint32_t lifetime ); /** * \brief Implementation of the ticket write callback * * \note See \c mbedtls_ssl_ticket_write_t for description */ mbedtls_ssl_ticket_write_t mbedtls_ssl_ticket_write; /** * \brief Implementation of the ticket parse callback * * \note See \c mbedtls_ssl_ticket_parse_t for description */ mbedtls_ssl_ticket_parse_t mbedtls_ssl_ticket_parse; /** * \brief Free a context's content and zeroize it. * * \param ctx Context to be cleaned up */ void mbedtls_ssl_ticket_free( mbedtls_ssl_ticket_context *ctx ); #ifdef __cplusplus } #endif #endif /* ssl_ticket.h */