/* * cipher.h * * common interface to ciphers * * David A. McGrew * Cisco Systems, Inc. */ /* * * Copyright (c) 2001-2017 Cisco Systems, Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials provided * with the distribution. * * Neither the name of the Cisco Systems, Inc. nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. * */ #ifndef SRTP_CIPHER_H #define SRTP_CIPHER_H #include "srtp.h" #include "crypto_types.h" /* for values of cipher_type_id_t */ #ifdef __cplusplus extern "C" { #endif /* * srtp_cipher_direction_t defines a particular cipher operation. * * A srtp_cipher_direction_t is an enum that describes a particular cipher * operation, i.e. encryption or decryption. For some ciphers, this * distinction does not matter, but for others, it is essential. */ typedef enum { srtp_direction_encrypt, /**< encryption (convert plaintext to ciphertext) */ srtp_direction_decrypt, /**< decryption (convert ciphertext to plaintext) */ srtp_direction_any /**< encryption or decryption */ } srtp_cipher_direction_t; /* * the srtp_cipher_pointer_t definition is needed * as srtp_cipher_t is not yet defined */ typedef struct srtp_cipher_t *srtp_cipher_pointer_t; /* * a srtp_cipher_alloc_func_t allocates (but does not initialize) a srtp_cipher_t */ typedef srtp_err_status_t (*srtp_cipher_alloc_func_t) (srtp_cipher_pointer_t *cp, int key_len, int tag_len); /* * a srtp_cipher_init_func_t [re-]initializes a cipher_t with a given key */ typedef srtp_err_status_t (*srtp_cipher_init_func_t) (void *state, const uint8_t *key); /* a srtp_cipher_dealloc_func_t de-allocates a cipher_t */ typedef srtp_err_status_t (*srtp_cipher_dealloc_func_t)(srtp_cipher_pointer_t cp); /* * a srtp_cipher_set_aad_func_t processes the AAD data for AEAD ciphers */ typedef srtp_err_status_t (*srtp_cipher_set_aad_func_t) (void *state, const uint8_t *aad, uint32_t aad_len); /* a srtp_cipher_encrypt_func_t encrypts data in-place */ typedef srtp_err_status_t (*srtp_cipher_encrypt_func_t) (void *state, uint8_t *buffer, unsigned int *octets_to_encrypt); /* a srtp_cipher_decrypt_func_t decrypts data in-place */ typedef srtp_err_status_t (*srtp_cipher_decrypt_func_t) (void *state, uint8_t *buffer, unsigned int *octets_to_decrypt); /* * a srtp_cipher_set_iv_func_t function sets the current initialization vector */ typedef srtp_err_status_t (*srtp_cipher_set_iv_func_t) (void *state, uint8_t *iv, srtp_cipher_direction_t direction); /* * a cipher_get_tag_func_t function is used to get the authentication * tag that was calculated by an AEAD cipher. */ typedef srtp_err_status_t (*srtp_cipher_get_tag_func_t) (void *state, uint8_t *tag, uint32_t *len); /* * srtp_cipher_test_case_t is a (list of) key, salt, plaintext, ciphertext, * and aad values that are known to be correct for a * particular cipher. this data can be used to test an implementation * in an on-the-fly self test of the correctness of the implementation. * (see the srtp_cipher_type_self_test() function below) */ typedef struct srtp_cipher_test_case_t { int key_length_octets; /* octets in key */ const uint8_t *key; /* key */ uint8_t *idx; /* packet index */ int plaintext_length_octets; /* octets in plaintext */ const uint8_t *plaintext; /* plaintext */ int ciphertext_length_octets; /* octets in plaintext */ const uint8_t *ciphertext; /* ciphertext */ int aad_length_octets; /* octets in AAD */ const uint8_t *aad; /* AAD */ int tag_length_octets; /* Length of AEAD tag */ const struct srtp_cipher_test_case_t *next_test_case; /* pointer to next testcase */ } srtp_cipher_test_case_t; /* srtp_cipher_type_t defines the 'metadata' for a particular cipher type */ typedef struct srtp_cipher_type_t { srtp_cipher_alloc_func_t alloc; srtp_cipher_dealloc_func_t dealloc; srtp_cipher_init_func_t init; srtp_cipher_set_aad_func_t set_aad; srtp_cipher_encrypt_func_t encrypt; srtp_cipher_encrypt_func_t decrypt; srtp_cipher_set_iv_func_t set_iv; srtp_cipher_get_tag_func_t get_tag; const char *description; const srtp_cipher_test_case_t *test_data; srtp_cipher_type_id_t id; } srtp_cipher_type_t; /* * srtp_cipher_t defines an instantiation of a particular cipher, with fixed * key length, key and salt values */ typedef struct srtp_cipher_t { const srtp_cipher_type_t *type; void *state; int key_len; int algorithm; } srtp_cipher_t; /* some bookkeeping functions */ int srtp_cipher_get_key_length(const srtp_cipher_t *c); /* * srtp_cipher_type_self_test() tests a cipher against test cases provided in * an array of values of key/srtp_xtd_seq_num_t/plaintext/ciphertext * that is known to be good */ srtp_err_status_t srtp_cipher_type_self_test(const srtp_cipher_type_t *ct); /* * srtp_cipher_type_test() tests a cipher against external test cases provided in * an array of values of key/srtp_xtd_seq_num_t/plaintext/ciphertext * that is known to be good */ srtp_err_status_t srtp_cipher_type_test(const srtp_cipher_type_t *ct, const srtp_cipher_test_case_t *test_data); /* * srtp_cipher_bits_per_second(c, l, t) computes (an estimate of) the * number of bits that a cipher implementation can encrypt in a second * * c is a cipher (which MUST be allocated and initialized already), l * is the length in octets of the test data to be encrypted, and t is * the number of trials * * if an error is encountered, then the value 0 is returned */ uint64_t srtp_cipher_bits_per_second(srtp_cipher_t *c, int octets_in_buffer, int num_trials); srtp_err_status_t srtp_cipher_type_alloc(const srtp_cipher_type_t *ct, srtp_cipher_t **c, int key_len, int tlen); srtp_err_status_t srtp_cipher_dealloc(srtp_cipher_t *c); srtp_err_status_t srtp_cipher_init(srtp_cipher_t *c, const uint8_t *key); srtp_err_status_t srtp_cipher_set_iv(srtp_cipher_t *c, uint8_t *iv, int direction); srtp_err_status_t srtp_cipher_output(srtp_cipher_t *c, uint8_t *buffer, uint32_t *num_octets_to_output); srtp_err_status_t srtp_cipher_encrypt(srtp_cipher_t *c, uint8_t *buffer, uint32_t *num_octets_to_output); srtp_err_status_t srtp_cipher_decrypt(srtp_cipher_t *c, uint8_t *buffer, uint32_t *num_octets_to_output); srtp_err_status_t srtp_cipher_get_tag(srtp_cipher_t *c, uint8_t *buffer, uint32_t *tag_len); srtp_err_status_t srtp_cipher_set_aad(srtp_cipher_t *c, const uint8_t *aad, uint32_t aad_len); /* * srtp_replace_cipher_type(ct, id) * * replaces srtp's existing cipher implementation for the cipher_type id * with a new one passed in externally. The new cipher must pass all the * existing cipher_type's self tests as well as its own. */ srtp_err_status_t srtp_replace_cipher_type(const srtp_cipher_type_t *ct, srtp_cipher_type_id_t id); #ifdef __cplusplus } #endif #endif /* SRTP_CIPHER_H */