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How secure is Linux's random number generator?

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Re: How secure is Linux's random number generator?

#21

Post by nwmcsween »

tptacek wrote: post #12
oellegaard wrote: post #7

Earlier quoted context omitted.

You are right that closed source doesn't mean its insecure - on the other hand, open source could prove that it is indeed secure. With new scandals coming up every week these days, about hidden backdoors in security software, I trust open source more than ever before.

Ironically, it's particularly vis a vis cryptographic random number generation where we can most easily show open source cryptography failing its users; Debian fatally broke the OpenSSL CSPRNG so badly that attackers could remotely brute force SSH keys.

Not defending the debain change but openssl code structure / readability is far from great, the only packages I would put behind openssl is libxml2, glib and glibc.

Re: How secure is Linux's random number generator?

#22

Post by oellegaard »

tptacek wrote: post #12
oellegaard wrote: post #7

Earlier quoted context omitted.

You are right that closed source doesn't mean its insecure - on the other hand, open source could prove that it is indeed secure. With new scandals coming up every week these days, about hidden backdoors in security software, I trust open source more than ever before.

Ironically, it's particularly vis a vis cryptographic random number generation where we can most easily show open source cryptography failing its users; Debian fatally broke the OpenSSL CSPRNG so badly that attackers could remotely brute force SSH keys.

Maybe no-one would have noticed if it was closed source. I bet if Microsoft released everything as Open Source there would be billions of bugs discovered.

Re: How secure is Linux's random number generator?

#23

Post by DanBC »

tptacek wrote: post #12
oellegaard wrote: post #7

Earlier quoted context omitted.

You are right that closed source doesn't mean its insecure - on the other hand, open source could prove that it is indeed secure. With new scandals coming up every week these days, about hidden backdoors in security software, I trust open source more than ever before.

Ironically, it's particularly vis a vis cryptographic random number generation where we can most easily show open source cryptography failing its users; Debian fatally broke the OpenSSL CSPRNG so badly that attackers could remotely brute force SSH keys.

Yes. And didn't that bug stay in Debian for two years?

Open source code still needs people looking at it.

Re: How secure is Linux's random number generator?

#24

Post by andrewcooke »

guns wrote: post #2

And here is the mailing list thread that the author refers to: https://lkml.org/lkml/2011/7/29/366

even after reading all that it's not clear to me whether the output from rdrand (the hardware instruction from intel that's opaque, if i'm understanding right) is mixed with other sources of entropy or not.

at https://lkml.org/lkml/2011/7/30/116 linus says We still do our own hashing on top of whatever entropy we get out of rdrand, and we would still have all our other stuff. but then goes on to say I'd be even more willing to just take something that just introduces a per-arch interface to get a "unsigned long [ptr]" that is random, and returning the number of bits of expected entropy in that thing. And for x86 CPU's with the RDRAND capability bit, I'd give Intel the benefit of the doubt and just make it do a single "rdrand" and return the full 64 bit [...] which sounds like it would not be mixed.

so what was the final outcome?

[also, perhaps worth mentioning explicitly - the argument that you shouldn't care too much about this is that if you don't trust intel then you're fucked anyway. which doesn't fill me with warmth and joy, but what can you do?]

Re: How secure is Linux's random number generator?

#25

Post by marshray »

oellegaard wrote: post #22
tptacek wrote: post #12

Earlier quoted context omitted.

Ironically, it's particularly vis a vis cryptographic random number generation where we can most easily show open source cryptography failing its users; Debian fatally broke the OpenSSL CSPRNG so badly that attackers could remotely brute force SSH keys.

Maybe no-one would have noticed if it was closed source. I bet if Microsoft released everything as Open Source there would be billions of bugs discovered.

The Debian RNG bug was noticed by folks who found identical certificates in the wild, not by code inspection. Similar RNG weaknesses are commonly found in closed systems as well, so it doesn't seem to be a particularly open/closed source thing.

Re: How secure is Linux's random number generator?

#27

Post by Groxx »

sejje wrote: post #11

Am I the only guy who can't figure out how to navigate mailing lists archives? These things are internet hell.

The 'read' view linked to here is pretty cryptic and weird, I agree entirely.

Try the "Messages sorted by: ... [ thread ] ..." link, it gives you a hierarchical view that's pretty understandable / navigable IMO.

Re: How secure is Linux's random number generator?

#28

Post by DanBC »

What's the suggested attack here?

That Intel is cooperating with the TLAs and providing a weak on-chip random number generator? Or a random number generator that can be made to be weak? Or what?

And how credible is the risk when that information is used to seed a pool of entropy, rather than being used raw?

Re: How secure is Linux's random number generator?

#29

Post by ReidZB »

jevinskie wrote: post #14
sejje wrote: post #11

Am I the only guy who can't figure out how to navigate mailing lists archives? These things are internet hell.

I agree. Try searching for the title on gmane.org

Here's the list on gmane: http://news.gmane.org/gmane.comp.security.cryptography.rando...

Not sure how to link a particular article in that view. The 'direct link' sends you to an article-only page. But the message by the OP appears as the third top-level thread in that view.

Re: How secure is Linux's random number generator?

#30

Post by mpyne »

newman314 wrote: post #17
jspaur wrote: post #6

Earlier quoted context omitted.

And even Linus talks about the NSA in that same thread a little lower: https://lkml.org/lkml/2011/7/30/116

And the next email where Ted says that the NSA are one of the good guys... Yeah, not so much.

Yeah, how dare the NSA develop SELinux and SHA-1.

I suppose I would just be feeding the conspiracy theories if I mentioned that NSA also pushed security work for X.org forward?

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