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RIOT/sys/include/crypto/modes/ctr.h 2.6 KB
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  /*
   * Copyright (C) 2015 Freie Universitรคt Berlin
   *
   * 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        ctr.h
   * @brief       Counter mode of operation for block ciphers
   *
   * @author      Freie Universitaet Berlin, Computer Systems & Telematics
   * @author      Nico von Geyso <nico.geyso@fu-berlin.de>
   */
  
  #ifndef CRYPTO_MODES_CTR_H
  #define CRYPTO_MODES_CTR_H
  
  #include "crypto/ciphers.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * @brief Encrypt data of arbitrary length in counter mode.
   *
   * @param cipher        Already initialized cipher struct
   * @param nonce_counter A nounce and a counter encoded in 16 octets. The counter
   *                      will be modified in each block encryption.
   * @param nonce_len     Length of the nonce in octets. As nounce and counter
   *                      have to fit in one aligned 16 octet block, maximum
   *                      length of nonce is limited by input_len:
   *                      16 - log_2(input_len)
   * @param input         pointer to input data to encrypt
   * @param length        length of the input data
   * @param output        pointer to allocated memory for encrypted data. It has
   *                      to be of size data_len.
   */
  int cipher_encrypt_ctr(cipher_t* cipher, uint8_t nonce_counter[16],
                         uint8_t nonce_len, uint8_t* input, size_t length,
                         uint8_t* output);
  
  
  /**
   * @brief Decrypt data of arbitrary length in counter mode. Encryption and
   *        decryption in ctr mode are basically the same.
   *
   * @param cipher        Already initialized cipher struct
   * @param nonce_counter A nounce and a counter encoded in 16 octets. The counter
   *                      will be modified in each block encryption.
   * @param nonce_len     Length of the nonce in octets. As nounce and counter
   *                      have to fit in one aligned 16 octet block, maximum
   *                      length of nonce is limited by input_len:
   *                      16 - log_2(input_len)
   * @param input         pointer to input data to encrypt
   * @param length        length of the input data
   * @param output        pointer to allocated memory for encrypted data. It has
   *                      to be of size data_len.
   */
  int cipher_decrypt_ctr(cipher_t* cipher, uint8_t nonce_counter[16],
                         uint8_t nonce_len, uint8_t* input, size_t length,
                         uint8_t* output);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* CRYPTO_MODES_CTR_H */