svn commit: trunk/busybox/loginutils

vda at busybox.net vda at busybox.net
Tue Dec 12 17:14:56 UTC 2006


Author: vda
Date: 2006-12-12 09:14:56 -0800 (Tue, 12 Dec 2006)
New Revision: 16855

Log:
passwd: added comment


Modified:
   trunk/busybox/loginutils/passwd.c


Changeset:
Modified: trunk/busybox/loginutils/passwd.c
===================================================================
--- trunk/busybox/loginutils/passwd.c	2006-12-12 17:01:26 UTC (rev 16854)
+++ trunk/busybox/loginutils/passwd.c	2006-12-12 17:14:56 UTC (rev 16855)
@@ -34,10 +34,15 @@
 
 	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);




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