The Raspberry Pi’s Hardware Random Number Generator • Hacker News Board

Re: The Raspberry Pi’s Hardware Random Number Generator

#41

Post by lambda » Thu, Jul 18, 2013, 2:55 AM UTC

Scaevolus wrote: post #24

DanBC wrote: post #12

Earlier quoted context omitted.

I found the link on Reddit. They're asking similar questions. So far Reddit hasn't got any answers; someone posted a link to a mailing list. Here's a similar link. ( https://lkml.org/lkml/2013/3/24/144 ) > This adds a driver for random number generator present on Broadcom BCM2835 SoC, used in Raspberry Pi and Roku 2 devices. Here's a github for the blob source ( https://github.com/raspberrypi/linux/blob/rpi-3.6.y/dri…

Some of these comments are particularly worrying: /* double speed, less random mode */ #define RNG_RBG2X 0x2 /* the initial numbers generated are "less random" so will be discarded */ #define RNG_WARMUP_COUNT 0x40000 A black box random number generator with some numbers being vaguely "less random"? That seems like an exceedingly poor idea.

I'm not sure that's worrying. Remember, this is hardware. Hardware takes time to turn on and get into a steady state. Many hardware random number generators are based on thermal noise. But in order to get in the correct range for the values to flip, you need to wait for the circuit to warm up to operating temperature.

Re: The Raspberry Pi’s Hardware Random Number Generator

#42

Post by sneak » Thu, Jul 18, 2013, 3:07 AM UTC

daurnimator wrote: post #14

schrodingersCat wrote: post #2

Perhaps this is a new application for the pi? A dedicated entropy appliance could be useful

Check out http://www.entropykey.co.uk/

I have one of these, they work well and are relatively inexpensive. I am particularly impressed by the design.

Re: The Raspberry Pi’s Hardware Random Number Generator

#43

Post by TerraHertz » Thu, Jul 18, 2013, 3:34 AM UTC

What I found unexpected about the Raspberry Pi, was that the CPU chip is closed - very little data available on what's in it. Suddenly 'discovered' hardware RNG being a case in point.

Re: The Raspberry Pi’s Hardware Random Number Generator

#44

Post by TerraHertz » Thu, Jul 18, 2013, 3:42 AM UTC

mahyarm wrote: post #20

shawnz wrote: post #11

Earlier quoted context omitted.

Intel's RDRAND is mentioned in the article as well, near the end. I suspect this article is doing so well because of the recent realization of Intel's involvement with the NSA, and the high potential for backdoors to be included in such a technology.

Broadcom is a similarly huge USA company in ARM computers & networking, are we sure they haven't been involved with the NSA either?

Being naturally suspicious, I can't help wondering why the Broadcom chip on the Raspberry Pi doesn't have full technical specs publicly available. Seriously, why not?

Re: The Raspberry Pi’s Hardware Random Number Generator

#45

Post by tptacek » Thu, Jul 18, 2013, 4:23 AM UTC

PeterisP wrote: post #22

mahyarm wrote: post #20

Earlier quoted context omitted.

Broadcom is a similarly huge USA company in ARM computers & networking, are we sure they haven't been involved with the NSA either?

We can't be sure, but it should be much easier to audit a small system like Pi, rather than an Intel processor that, above all, can be remotely patched.

Huh? Much easier to audit a Broadcom SOC? Than what, auditing deliberately obfuscated hardware designs like the modern DirecTV smartcards?

The idea that it's in any sense easy to "audit" the Raspberry Pi's hardware is head-explodey. No you can't.

This is pure back-rationalization. You like the Raspberry Pi. You don't like Intel Corporation. So you come up with a reason why the R-Pi's hardware RNG might be more trustworthy than than the hardware RNG in a modern Intel computer. It's a crazy reason, not least because the R-Pi's core is produced by another giant semiconductor company.

Re: The Raspberry Pi’s Hardware Random Number Generator

#46

Post by marshray » Thu, Jul 18, 2013, 5:25 AM UTC

TerraHertz wrote: post #44

mahyarm wrote: post #20

Earlier quoted context omitted.

Broadcom is a similarly huge USA company in ARM computers & networking, are we sure they haven't been involved with the NSA either?

Being naturally suspicious, I can't help wondering why the Broadcom chip on the Raspberry Pi doesn't have full technical specs publicly available. Seriously, why not?

Their customers are device makers, not small time developers or end users. They just don't want to disclose the information to people without various agreements (and hard sales leads) in place.

Re: The Raspberry Pi’s Hardware Random Number Generator

#47

Post by marshray » Thu, Jul 18, 2013, 5:26 AM UTC

wodenokoto wrote: post #33

cpeterso wrote: post #32

Here is my proposed RNG for network devices that don't generate much entropy of their own: strace -Tiv -ttt nice curl -Lv --raw $URL 2>&1 | shasum | dd bs=1 count=2 2>/dev/null Possible values of $URL might be https://news.google.com , https://en.wikipedia.org/wiki/Special:Random , or the Twitter Firehose. :)

If you are connected to the internet, why not get your randomness from http://www.random.org/ ?

This thread is a joke, right?

Re: The Raspberry Pi’s Hardware Random Number Generator

#48

Post by ippisl » Thu, Jul 18, 2013, 5:31 AM UTC

tptacek wrote: post #37

PeterisP wrote: post #7

It may well be that small hardware could be better for generating keys, as it is much easier to audit the total system, and I'd trust it more than an Intel processor with known remote patching capabilities. If you're security-sensitive then it could be good having a small, dedicated system like the Pi, and make sure that your private key never leaves it.

If you don't trust a chip vendor's remote patching, there's nothing you can trust on the chip cryptographically at all.

Are there any possible realistic solutions to the trusted hardware issue?

Re: The Raspberry Pi’s Hardware Random Number Generator

#49

Post by ooorlllyyy » Thu, Jul 18, 2013, 5:47 AM UTC

tptacek wrote: post #37

PeterisP wrote: post #7

It may well be that small hardware could be better for generating keys, as it is much easier to audit the total system, and I'd trust it more than an Intel processor with known remote patching capabilities. If you're security-sensitive then it could be good having a small, dedicated system like the Pi, and make sure that your private key never leaves it.

If you don't trust a chip vendor's remote patching, there's nothing you can trust on the chip cryptographically at all.

Wait a second, wouldn't this statement imply that things like cert-pinning and PFS are completely useless?

Does skepticism of remote patching while trust of the original chip not protect you against being specially targeted if you assume that the chips aren't being wholesale manufactured with back doors built in?

Re: The Raspberry Pi’s Hardware Random Number Generator

#50

Post by Dylan16807 » Thu, Jul 18, 2013, 6:27 AM UTC

hamburglar wrote: post #13

The article is a bit vague about what exactly they're trying to say. What was unexpected? I read it three times before I decided they're comparing a lousy homegrown software RNG to the Pi's hardware RNG, which turns out to be good. Yes? Why would that be unexpected?

Especially confusing is when the article suddenly says "This is not random". But oh what it means is that the upcoming part of the article, on a completely different topic from the Pi, is not random.