1 /* 2 * Copyright (C) 2023 - This file is part of libecc project 3 * 4 * Authors: 5 * Ryad BENADJILA <ryadbenadjila@gmail.com> 6 * Arnaud EBALARD <arnaud.ebalard@ssi.gouv.fr> 7 * 8 * This software is licensed under a dual BSD and GPL v2 license. 9 * See LICENSE file at the root folder of the project. 10 */ 11 #include <libecc/utils/utils_rand.h> 12 13 /* Unsafe random source: 14 * Initial seeding is performed using good entropy, then 15 * a congruential linear system is used. 16 */ 17 static u64 seed = 0; get_unsafe_random(unsigned char * buf,u16 len)18int get_unsafe_random(unsigned char *buf, u16 len) 19 { 20 int ret; 21 u64 a, b; 22 u16 i, j; 23 a = (u64)2862933555777941757; 24 b = (u64)3037000493; 25 26 if(seed == 0){ 27 ret = get_random((u8*)&seed, sizeof(seed)); 28 if(ret){ 29 ret = -1; 30 goto err; 31 } 32 } 33 34 i = 0; 35 while(i < len){ 36 /* Use a congruential linear generator */ 37 seed = ((a * seed) + b); 38 39 for(j = 0; j < sizeof(seed); j++){ 40 if((i + j) < len){ 41 buf[i + j] = (u8)((seed >> (j * 8)) & 0xff); 42 } 43 } 44 i = (u16)(i + sizeof(seed)); 45 } 46 47 ret = 0; 48 49 err: 50 return ret; 51 } 52