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/*
* Copyright (C) 2013 Freie Universitรคt Berlin, Computer Systems & Telematics
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup sys_crypto
* @{
*
* @file
* @brief Headers for the packet encryption class. They are used to encrypt single packets.
*
* @author Freie Universitaet Berlin, Computer Systems & Telematics
* @author Nicolai Schmittberger <nicolai.schmittberger@fu-berlin.de>
* @author Zakaria Kasmi <zkasmi@inf.fu-berlin.de>
* @author Mark Essien <markessien@gmail.com>
*/
#ifndef CRYPTO_CIPHERS_H_
#define CRYPTO_CIPHERS_H_
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
/* Shared header file for all cipher algorithms */
/* Set the algorithms that should be compiled in here. When these defines
* are set, then packets will be compiled 5 times.
*/
// #define CRYPTO_THREEDES
// #define CRYPTO_AES
// #define CRYPTO_TWOFISH
/** @brief the length of keys in bytes */
#define CIPHERS_MAX_KEY_SIZE 20
#define CIPHER_MAX_BLOCK_SIZE 16
/**
* Context sizes needed for the different ciphers.
* Always order by number of bytes descending!!! <br><br>
*
* threedes needs 24 bytes <br>
* aes needs CIPHERS_MAX_KEY_SIZE bytes <br>
* twofish needs CIPHERS_MAX_KEY_SIZE bytes <br>
*/
#if defined(CRYPTO_THREEDES)
#define CIPHER_MAX_CONTEXT_SIZE 24
#elif defined(CRYPTO_AES)
#define CIPHER_MAX_CONTEXT_SIZE CIPHERS_MAX_KEY_SIZE
#elif defined(CRYPTO_TWOFISH)
#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
/** Is returned by the cipher_init functions, if the coresponding alogirithm has not been included in the build */
#define CIPHER_ERR_BAD_CONTEXT_SIZE 0
/** Returned by cipher_init upon succesful initialization of a cipher. */
#define CIPHER_INIT_SUCCESS 1
/**
* @brief the context for cipher-operations
*/
typedef struct {
uint8_t context[CIPHER_MAX_CONTEXT_SIZE]; /**< buffer for cipher operations */
} cipher_context_t;
/**
* @brief BlockCipher-Interface for the Cipher-Algorithms
*/
typedef struct cipher_interface_st {
/** Blocksize of this cipher */
uint8_t block_size;
/** Maximum key size for this cipher */
uint8_t max_key_size;
/** the init function */
int (*init)(cipher_context_t* ctx, const uint8_t* key, uint8_t key_size);
/** the encrypt function */
int (*encrypt)(const cipher_context_t* ctx, const uint8_t* plain_block,
uint8_t* cipher_block);
/** the decrypt function */
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_3DES;
extern const cipher_id_t CIPHER_AES_128;
extern const cipher_id_t CIPHER_TWOFISH;
/**
* @brief basic struct for using block ciphers
* contains the cipher interface and the context
*/
typedef struct {
const cipher_interface_t* interface; /**< BlockCipher-Interface for the
Cipher-Algorithms */
cipher_context_t context; /**< The encryption context (buffer)
for the algorithm */
} cipher_t;
/**
* @brief Initialize new cipher state
*
* @param cipher cipher struct to init (already allocated memory)
* @param cipher_id cipher algorithm id
* @param key encryption key to use
* @param key_size length of the encryption key
*
* @return CIPHER_INIT_SUCCESS if the initialization was successful.
* The command may be unsuccessful if the key size is not valid.
* CIPHER_ERR_BAD_CONTEXT_SIZE if CIPHER_MAX_CONTEXT_SIZE has not been defined (which means that the cipher has not been included in the build)
*/
int cipher_init(cipher_t* cipher, cipher_id_t cipher_id, const uint8_t* key,
uint8_t key_size);
/**
* @brief Encrypt data of BLOCK_SIZE length
* *
*
* @param cipher Already initialized cipher struct
* @param input pointer to input data to encrypt
* @param output pointer to allocated memory for encrypted data. It has to
* be of size BLOCK_SIZE
*/
int cipher_encrypt(const cipher_t* cipher, const uint8_t* input, uint8_t* output);
/**
* @brief Decrypt data of BLOCK_SIZE length
* *
*
* @param cipher Already initialized cipher struct
* @param input pointer to input data (of size BLOCKS_SIZE) to decrypt
* @param output pointer to allocated memory for decrypted data. It has to
* be of size BLOCK_SIZE
*/
int cipher_decrypt(const cipher_t* cipher, const uint8_t* input, uint8_t* output);
/**
* @brief Get block size of cipher
* *
*
* @param cipher Already initialized cipher struct
*/
int cipher_get_block_size(const cipher_t* cipher);
#ifdef __cplusplus
}
#endif
/** @} */
#endif /* CRYPTO_CIPHERS_H_ */
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