Re: /dev/random and /dev/psaux: too much entropy assumed?

Damien Miller (dmiller@ilogic.com.au)
Wed, 2 Jun 1999 13:08:21 +1000 (EST)


On Tue, 1 Jun 1999, C. Scott Ananian wrote:

> my point was more subtle: it is your responsibility to verify that the
> uses you put /dev/random to are appropriate. monte-carlo integration and
> n-body simulations are *not* kernel issues and thus *not* appropriate for
> linux-kernel. attacks on tcp sequence numbers *are* kernel issues, but no
> one has ever claimed that statistical uniformity was relevant here.

It is relevant:

from drivers/char/random.c:

* This routine gathers environmental noise from device drivers, etc.,
* and returns good random numbers, suitable for cryptographic use.
* Besides the obvious cryptographic uses, these numbers are also good
* for seeding TCP sequence numbers, and other places where it is
* desirable to have numbers which are not only random, but hard to
* predict by an attacker.

and

* The two other interfaces are two character devices /dev/random and
* /dev/urandom. /dev/random is suitable for use when very high
* quality randomness is desired (for example, for key generation or
* one-time pads), as it will only return a maximum of the number of

/dev/random is explicitly designed for use by user-space cryptography
software. If its collection and entrophy estimation is erroneous then
it is a bug which should be fixed where it happens - in the driver.

Regards,
Damien Miller

--
| "Bombay is 250ms from New York in the new world order" - Alan Cox
| Damien Miller - http://www.ilogic.com.au/~dmiller
| Email: dmiller@ilogic.com.au (home) -or- damien@ibs.com.au (work)

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