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1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
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
10 #include "forward.h"
11
12 #ifdef __cplusplus
13 extern "C" {
14 #endif
15
16 #define FSPRG_RECOMMENDED_SECPAR 1536
17 #define FSPRG_RECOMMENDED_SEEDLEN (96/8)
18
19 size_t FSPRG_mskinbytes(unsigned secpar) _const_;
20 size_t FSPRG_mpkinbytes(unsigned secpar) _const_;
21 size_t FSPRG_stateinbytes(unsigned secpar) _const_;
22
23 /* Setup msk and mpk. Providing seed != NULL makes this algorithm deterministic. */
24 int FSPRG_GenMK(void *msk, void *mpk, const void *seed, size_t seedlen, unsigned secpar);
25
26 /* Initialize state deterministically in dependence on seed. */
27 /* Note: in case one wants to run only one GenState0 per GenMK it is safe to use
28 the same seed for both GenMK and GenState0.
29 */
30 int FSPRG_GenState0(void *state, const void *mpk, const void *seed, size_t seedlen);
31
32 int FSPRG_Evolve(void *state);
33
34 uint64_t FSPRG_GetEpoch(const void *state) _pure_;
35
36 /* Seek to any arbitrary state (by providing msk together with seed from GenState0). */
37 int FSPRG_Seek(void *state, uint64_t epoch, const void *msk, const void *seed, size_t seedlen);
38
39 int FSPRG_GetKey(const void *state, void *key, size_t keylen, uint32_t idx);
40
41 #ifdef __cplusplus
42 }
43 #endif