While debugging Exim4's GnuTLS interface, I recently found out that reading from /dev/urandom depletes entropy as much as reading from /dev/random would. This has somehow surprised me since I have always believed that /dev/urandom has lower quality entropy than /dev/random, but lots of it.
This also means that I can "sabotage" applications reading from /dev/random just by continuously reading from /dev/urandom, even not meaning to do any harm. Before I file a bug on bugzilla, can I ask why /dev/urandom wasn't implemented as a PRNG which is periodically (say, every 1024 bytes or even more) seeded from /dev/random? That way, /dev/random has a much higher chance of holding enough entropy for applications that really need "good" entropy. Entropy depletion has become an issue on Linux systems since the network was removed from the group of entropy sources a few years ago. Of the around 20 Linux systems that I currently have root privileges on, only two have a hardware RNG. What can I do to keep sufficiently high entropy pools even if I read from /dev/urandom more than once in a while? Greetings Marc -- ----------------------------------------------------------------------------- Marc Haber | "I don't trust Computers. They | Mailadresse im Header Mannheim, Germany | lose things." Winona Ryder | Fon: *49 621 72739834 Nordisch by Nature | How to make an American Quilt | Fax: *49 3221 2323190 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
