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| author | Mikko Juola <mikko.juola@kolumbus.fi> | 2009-10-01 14:37:49 +0530 |
|---|---|---|
| committer | Darshan Shaligram <dshaligram@users.sourceforge.net> | 2009-10-01 14:42:06 +0530 |
| commit | fb49425915aef7877fedfc58730cef8bcf58aee7 (patch) | |
| tree | 32a12f676185d673ce1b4091b9aff57e5c22ad83 /crawl-ref/source/stuff.cc | |
| parent | f44f2bc6f575f26209d70243fb9ca7a07893bc59 (diff) | |
| download | crawl-ref-fb49425915aef7877fedfc58730cef8bcf58aee7.tar.gz crawl-ref-fb49425915aef7877fedfc58730cef8bcf58aee7.zip | |
Harden the PRNG for public servers.
Detailed discussion is here: http://www.genodeen.net/index.clua?cwrng
Signed-off-by: Darshan Shaligram <dshaligram@users.sourceforge.net>
Diffstat (limited to 'crawl-ref/source/stuff.cc')
| -rw-r--r-- | crawl-ref/source/stuff.cc | 42 |
1 files changed, 41 insertions, 1 deletions
diff --git a/crawl-ref/source/stuff.cc b/crawl-ref/source/stuff.cc index d825f8e5b4..6155572681 100644 --- a/crawl-ref/source/stuff.cc +++ b/crawl-ref/source/stuff.cc @@ -45,6 +45,10 @@ REVISION("$Rev$"); #endif +#ifdef MORE_HARDENED_PRNG +#include "sha256.h" +#endif + #ifdef DOS #include <conio.h> #endif @@ -470,6 +474,12 @@ unsigned char get_ch() return gotched; } +void seed_rng(unsigned long* seed_key, size_t num_keys) +{ + // MT19937 -- see mt19937ar.cc for details/licence + init_by_array(seed_key, num_keys); +} + void seed_rng(long seed) { // MT19937 -- see mt19937ar.cc for details/licence @@ -480,17 +490,43 @@ void seed_rng() { unsigned long seed = time( NULL ); #ifdef USE_MORE_SECURE_SEED + + /* (at least) 256-bit wide seed */ + unsigned long seed_key[8]; + struct tms buf; seed += times( &buf ) + getpid(); -#endif + seed_key[0] = seed; + + /* Try opening from various system provided (hopefully) CSPRNGs */ + FILE* seed_f = fopen("/dev/urandom", "rb"); + if (!seed_f) + seed_f = fopen("/dev/random", "rb"); + if (!seed_f) + seed_f = fopen("/dev/srandom", "rb"); + if (!seed_f) + seed_f = fopen("/dev/arandom", "rb"); + if (seed_f) + { + fread(&seed_key[1], sizeof(unsigned long), 7, seed_f); + fclose(seed_f); + } + seed_rng(seed_key, 8); + +#else seed_rng(seed); +#endif } // MT19937 -- see mt19937ar.cc for details unsigned long random_int( void ) { +#ifndef MORE_HARDENED_PRNG return (genrand_int32()); +#else + return (sha256_genrand()); +#endif } int random_range(int low, int high) @@ -586,7 +622,11 @@ int random2(int max) if (max <= 1) return (0); + #ifdef MORE_HARDENED_PRNG + return (static_cast<int>(sha256_genrand() / (0xFFFFFFFFUL / max + 1))); + #else return (static_cast<int>(genrand_int32() / (0xFFFFFFFFUL / max + 1))); + #endif } bool coinflip(void) |