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RIOT/sys/include/crypto/ciphers.h 5.03 KB
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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
  
  /** @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>
   */
  #if defined(CRYPTO_THREEDES)
      #define CIPHER_MAX_CONTEXT_SIZE 24
  #elif defined(CRYPTO_AES)
      #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_AES_128;
  
  
  /**
   * @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 */