cipher.h
/*
* 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,
srtp_direction_decrypt,
srtp_direction_any
} 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 */
unsigned int plaintext_length_octets; /* octets in plaintext */
const uint8_t *plaintext; /* plaintext */
unsigned 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_decrypt_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 */
srtp_err_status_t
srtp_err_status_t
srtp_err_status_t defines error codes.
Definition srtp.h:181
srtp_cipher_type_id_t
uint32_t srtp_cipher_type_id_t
A srtp_cipher_type_id_t is an identifier for a particular cipher type.
Definition srtp.h:156
srtp_cipher_t
Definition cipher.h:168
srtp_cipher_test_case_t
Definition cipher.h:134
srtp_cipher_type_t
Definition cipher.h:150