passwd: added comment

1 files changed, 6 insertions, 1 deletions

diff --git a/loginutils/passwd.c b/loginutils/passwd.c
index a062596b4..c28e9b80e 100644
--- a/loginutils/passwd.c
+++ b/loginutils/passwd.c
@@ -34,10 +34,15 @@ static void crypt_make_salt(char *p, int cnt)
 
         x += getpid() + time(NULL) + clock();
         do {
-                /* x = (x*1664525 + 1013904223) mod 2^32 generator is lame
+                /* x = (x*1664525 + 1013904223) % 2^32 generator is lame
                  * (low-order bit is not "random", etc...),
                  * but for our purposes it is good enough */
                 x = x*1664525 + 1013904223;
+                /* BTW, Park and Miller's "minimal standard generator" is
+                 * x = x*16807 % ((2^31)-1)
+                 * It has no problem with visibly alternating lowest bit
+                 * but is also weak in cryptographic sense + needs div,
+                 * which needs more code (and slower) on many CPUs */
                 *p++ = i64c(x >> 16);
                 *p++ = i64c(x >> 22);
         } while (--cnt);