ciphers.h

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/*
 * SPDX-FileCopyrightText: 2013 Freie Universität Berlin, Computer Systems & Telematics
 * SPDX-License-Identifier: LGPL-2.1-only
 */
 
#pragma once

 
#include <stdint.h>
#include "modules.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
/* Shared header file for all cipher algorithms */

#if IS_USED(MODULE_CRYPTO_AES_256)
    #define CIPHERS_MAX_KEY_SIZE 32
#elif IS_USED(MODULE_CRYPTO_AES_192)
    #define CIPHERS_MAX_KEY_SIZE 24
#else
    #define CIPHERS_MAX_KEY_SIZE 16
#endif
#define CIPHER_MAX_BLOCK_SIZE 16

#if IS_USED(MODULE_CRYPTO_AES_256) || IS_USED(MODULE_CRYPTO_AES_192) || \
    IS_USED(MODULE_CRYPTO_AES_128)
    #define CIPHER_MAX_CONTEXT_SIZE CIPHERS_MAX_KEY_SIZE
#else
/* 0 is not a possibility because 0-sized arrays are not allowed in ISO C */
    #define CIPHER_MAX_CONTEXT_SIZE 1
#endif
 
/* return codes */
 
#define CIPHER_ERR_INVALID_KEY_SIZE   -3
#define CIPHER_ERR_INVALID_LENGTH     -4
#define CIPHER_ERR_ENC_FAILED         -5
#define CIPHER_ERR_DEC_FAILED         -6
#define CIPHER_ERR_BAD_CONTEXT_SIZE    0
#define CIPHER_INIT_SUCCESS            1

typedef struct {
    uint8_t key_size;                           
    uint8_t context[CIPHER_MAX_CONTEXT_SIZE];   
} cipher_context_t;

typedef struct cipher_interface_st {
    uint8_t block_size;

    int (*init)(cipher_context_t *ctx, const uint8_t *key, uint8_t key_size);

    int (*encrypt)(const cipher_context_t *ctx, const uint8_t *plain_block,
                   uint8_t *cipher_block);

    int (*decrypt)(const cipher_context_t *ctx, const uint8_t *cipher_block,
                   uint8_t *plain_block);
} cipher_interface_t;

typedef const cipher_interface_t *cipher_id_t;

extern const cipher_id_t CIPHER_AES;

typedef struct {
    const cipher_interface_t *interface;    
    cipher_context_t context;               
} cipher_t;

int cipher_init(cipher_t *cipher, cipher_id_t cipher_id, const uint8_t *key,
                uint8_t key_size);

int cipher_encrypt(const cipher_t *cipher, const uint8_t *input,
                   uint8_t *output);

int cipher_decrypt(const cipher_t *cipher, const uint8_t *input,
                   uint8_t *output);

int cipher_get_block_size(const cipher_t *cipher);
 
#ifdef __cplusplus
}
#endif