Bug 26972 – predictable random number generator used in web browsers

• Status: RESOLVED
• Resolution: DUPLICATE
• Component: JavaScriptCore

[Michael Gilbert]

hello,

it has been discovered that all of the major web browsers use a
predictable pseudo-random number generator (PRNG).  please see
reference [0]. the robust solution is to switch to a provably
unpredictable PRNG such as Blum Blum Shub [1,2].

[0] http://www.trusteer.com/temporary-user-tracking-in-major-browsers
[1] Lenore Blum, Manual Blum, and Michael Shub, "A Simple Unpredictable
Pseudo-Random Number Generator," SIAM Journal on Computing, volume 15,
pages 364-383, May 1986.
[2] http://rng.doesntexist.org/gmpbbs

[Michael Gilbert]

this is already publicly disclosed, so there is no reason to restrict access to this report.  however, it seems i can't uncheck the box to do that...

[Adam Barth]

I have unchecked the box for you.

[Sam Weinig]

This is only a problem on Windows at the moment, where we found the existing cryptographically secure PRNG to be a hefty performance regression on some tests (I believe it was the JS iBench test).  Mac OS uses arc4random for all random numbers, which I believe is suitable, and is noted in the paper.  I think we should probably just include arc4random in the tree and call it a day.

[Michael Gilbert]

the paper does not mention webkit on linux.  what is the status of the PRNG there?

[Radar WebKit Bug Importer]

<rdar://problem/22839305>

[David Kilzer (:ddkilzer)]

Dupe:
Bug 41868: [JSC] Math.random is predictable which may lead to cross-domain information leakage and temporary user tracking attacks

*** This bug has been marked as a duplicate of bug 41868 ***