src/journal/fsprg.h

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