src/sizes.h

   1 /*
   2  * transsip - the telephony toolkit
   3  * By Daniel Borkmann <daniel@transsip.org>
   4  * Copyright 2012 Daniel Borkmann <dborkma@tik.ee.ethz.ch>
   5  * Subject to the GPL, version 2.
   6  * Based on Bhaskar Biswas and Nicolas Sendrier McEliece
   7  * implementation, LGPL 2.1.
   8  */
   9
  10 #ifndef SIZES_H
  11 #define SIZES_H
  12
  13 #include <stdint.h>
  14
  15 #include "params.h"
  16 #include "gf.h"
  17
  18 #define NB_ERRORS               ERROR_WEIGHT
  19 #define EXT_DEGREE              LOG_LENGTH
  20
  21 #define LENGTH                  (1 << EXT_DEGREE)
  22 #define CODIMENSION             (NB_ERRORS * EXT_DEGREE)
  23 #define DIMENSION               (LENGTH - CODIMENSION)
  24
  25 /* number of bytes needed for storing nb_bits bits */
  26 #define BITS_TO_BYTES(nb_bits)  (((nb_bits) - 1) / 8 + 1)
  27
  28 /* number bits in one long */
  29 #define BIT_SIZE_OF_LONG        (8 * sizeof(uint32_t))
  30
  31 /* number of long needed for storing nb_bits bits */
  32 #define BITS_TO_LONG(nb_bits)   (((nb_bits) - 1) / BIT_SIZE_OF_LONG + 1)
  33
  34 #define SECRETKEY_BYTES         (LENGTH * sizeof(uint32_t) * \
  35                                  BITS_TO_LONG(CODIMENSION) + \
  36                                  (LENGTH + 1 + (NB_ERRORS + 1) * \
  37                                   NB_ERRORS) * sizeof(gf16_t))
  38
  39 #define PUBLICKEY_BYTES         (BITS_TO_LONG(CODIMENSION) * \
  40                                  sizeof(uint32_t) * DIMENSION)
  41
  42 #define CLEARTEXT_LENGTH        (DIMENSION + ERROR_SIZE)
  43 #define CLEARTEXT_BYTES         BITS_TO_BYTES(CLEARTEXT_LENGTH)
  44 #define CIPHERTEXT_BYTES        BITS_TO_BYTES(LENGTH)
  45
  46 /*
  47  * CLEARTEXT_BYTES is the number of bytes of the block to be encrypted
  48  * (= CLEARTEXT_LENGTH / 8 rounded up)
  49  *
  50  * MESSAGE_BYTES is the number of information bytes in each block
  51  * (= CLEARTEXT_LENGTH / 8 rounded down possibly one less than
  52  *    CLEARTEXT_BYTES)
  53  *
  54  * To add a semantically secure conversion, one can reduce
  55  * MESSAGE_BYTES accordingly and add a randomization layer before
  56  * encryption (and after decryption)
  57  */
  58
  59 #define MESSAGE_BYTES           (CLEARTEXT_LENGTH / 8)
  60
  61 #endif /* SIZES_H */