src/journal/fsprg.h

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #ifndef __fsprgh__
   4 #define __fsprgh__
   5
   6 /*
   7  * fsprg v0.1  -  (seekable) forward-secure pseudorandom generator
   8  * Copyright (C) 2012 B. Poettering
   9  * Contact: fsprg@point-at-infinity.org
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; either
  14  * version 2.1 of the License, or (at your option) any later version.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  24  * 02110-1301  USA
  25  *
  26  */
  27
  28 #include <inttypes.h>
  29 #include <sys/types.h>
  30
  31 #include "macro.h"
  32 #include "util.h"
  33
  34 #ifdef __cplusplus
  35 extern "C" {
  36 #endif
  37
  38 #define FSPRG_RECOMMENDED_SECPAR 1536
  39 #define FSPRG_RECOMMENDED_SEEDLEN (96/8)
  40
  41 size_t FSPRG_mskinbytes(unsigned secpar) _const_;
  42 size_t FSPRG_mpkinbytes(unsigned secpar) _const_;
  43 size_t FSPRG_stateinbytes(unsigned secpar) _const_;
  44
  45 /* Setup msk and mpk. Providing seed != NULL makes this algorithm deterministic. */
  46 void FSPRG_GenMK(void *msk, void *mpk, const void *seed, size_t seedlen, unsigned secpar);
  47
  48 /* Initialize state deterministically in dependence on seed. */
  49 /* Note: in case one wants to run only one GenState0 per GenMK it is safe to use
  50    the same seed for both GenMK and GenState0.
  51 */
  52 void FSPRG_GenState0(void *state, const void *mpk, const void *seed, size_t seedlen);
  53
  54 void FSPRG_Evolve(void *state);
  55
  56 uint64_t FSPRG_GetEpoch(const void *state) _pure_;
  57
  58 /* Seek to any arbitrary state (by providing msk together with seed from GenState0). */
  59 void FSPRG_Seek(void *state, uint64_t epoch, const void *msk, const void *seed, size_t seedlen);
  60
  61 void FSPRG_GetKey(const void *state, void *key, size_t keylen, uint32_t idx);
  62
  63 #ifdef __cplusplus
  64 }
  65 #endif
  66
  67 #endif