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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 implementation of the RC5 Cipher-Algorithm
*
* @author Freie Universitaet Berlin, Computer Systems & Telematics
* @author Nicolai Schmittberger <nicolai.schmittberger@fu-berlin.de>
* @author Zakaria Kasmi <zkasmi@inf.fu-berlin.de>
*/
#include "crypto/ciphers.h"
#ifndef RC5_H_
#define RC5_H_
#ifdef __cplusplus
extern "C" {
#endif
#define RC5_32_P 0xB7E15163L
#define RC5_32_Q 0x9E3779B9L
#define RC5_32_MASK 0xffffffffL
#define RC5_ROUNDS 12
#define rotl32(a,b) fastrol32((a), (b))
#define rotr32(a,b) fastror32((a), (b))
#define rol32(a, n) ( a = (((a) << (n)) | ((a) >> (32-(n)))))
#define ror32(a, n) ( a = (((a) >> (n)) | ((a) << (32-(n)))))
#define fastrol32 rol32
#define fastror32 ror32
// convert a 4byte char array to a unsigned long
// [assumes least significant byte of char array is first]
#define c2l(c,l) (l =((unsigned long)(*((c)))), \
l|=((unsigned long)(*((c+1))))<< 8L, \
l|=((unsigned long)(*((c+2))))<<16L, \
l|=((unsigned long)(*((c+3))))<<24L)
// convert an unsigned long to a 4 byte char array
// [assumes least significant byte of char array is first]
#define l2c(l,c) (*((c)) =(unsigned char)(((l) )&0xff), \
*((c+1))=(unsigned char)(((l)>> 8L)&0xff), \
*((c+2))=(unsigned char)(((l)>>16L)&0xff), \
*((c+3))=(unsigned char)(((l)>>24L)&0xff))
// 2 * (ROUNDS +1) * 4
// 2 * 13 * 4 = 104 bytes
#define RC5_CONTEXT_SIZE (2 * (RC5_ROUNDS + 1))
/**
* @brief the cipher_context_t adapted for RC5
*/
typedef struct {
/** @cond INTERNAL */
uint32_t skey [RC5_CONTEXT_SIZE];
/** @endcond */
} rc5_context_t;
/**
* @brief Initialize the BlockCipher.
*
* @param context the cipher_context_t-struct to save the initialization
* of the cipher in
* @param keySize the size of the key
* @param key a pointer to the key
*
* @return Whether initialization was successful. The command may be
* unsuccessful if the key size is not valid for the
* given cipher implementation.
*/
int rc5_init(cipher_context_t *context, const uint8_t *key, uint8_t keySize);
/**
* @brief Encrypts a single block (of blockSize) using the passed context.
*
* PROLOGUE: 24 cycles
* INIT: 48 cycles
* LOOP: 1680 cycles (12 + fastrol [= 42] + 16) * 2 * RC5_ROUNDS
* CLOSE: 24 cycles
* =====================
* 1776 cycles (avg case)
*
* @param context the cipher_context_t-struct to save the updated key in
* @param plain_block a plaintext block of blockSize
* @param cipher_block the resulting ciphertext block of blockSize
*
* @return Whether the encryption was successful. Possible failure reasons
* include not calling init().
*/
int rc5_encrypt(const cipher_context_t *context, const uint8_t *plain_block, uint8_t *cipher_block);
/**
* @brief Decrypts a single block (of blockSize) using the key and the
* keySize.
*
* @param context the cipher_context_t-struct to use for this decryption
* @param cipherBlock a ciphertext block of blockSize
* @param plainBlock the resulting plaintext block of blockSize
*
* @return Whether the decryption was successful. Possible failure reasons
* include not calling init() or an unimplimented decrypt function.
*/
int rc5_decrypt(const cipher_context_t *context, const uint8_t *cipherBlock,
uint8_t *plainBlock);
#ifdef __cplusplus
}
#endif
/** @} */
#endif /* RC5_H_ */
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