From 649df740b717000030c27d70209f4491da3a63f9 Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Fri, 3 Sep 2004 06:33:35 +0000 Subject: [PATCH] Comments. --- src/lib/random.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/src/lib/random.c b/src/lib/random.c index 3fcf62d..63d798d 100644 --- a/src/lib/random.c +++ b/src/lib/random.c @@ -3,11 +3,24 @@ #include #include "debug.h" -/* RC4-based pseudo-random state. */ -static uint8_t s[256]; -static uint8_t s_i, s_j; -static bool inited; +/* RC4-based pseudo-random number generator (PRNG). + RC4 is a stream cipher. We're not using it here for its + cryptographic properties, but because it is easy to implement + and its output is plenty random for non-cryptographic + purposes. + + See http://en.wikipedia.org/wiki/RC4_(cipher) for information + on RC4.*/ + +/* RC4 state. */ +static uint8_t s[256]; /* S[]. */ +static uint8_t s_i, s_j; /* i, j. */ + +/* Already initialized? */ +static bool inited; + +/* Swaps the bytes pointed to by A and B. */ static inline void swap_byte (uint8_t *a, uint8_t *b) { @@ -16,6 +29,8 @@ swap_byte (uint8_t *a, uint8_t *b) *b = t; } +/* Initializes the PRNG with the given SEED. + Does nothing if the PRNG has already been initialized. */ void random_init (unsigned seed) { @@ -38,6 +53,7 @@ random_init (unsigned seed) inited = true; } +/* Writes SIZE random bytes into BUF. */ void random_bytes (void *buf_, size_t size) { -- 2.30.2