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