RE: TCP sequence numbers

1999-09-07 Thread Kris Kennaway
On Thu, 2 Sep 1999, Geoff Rehmet wrote: > > I'd expect Yarrow to be (perhaps quite a bit) slower than our existing > > PRNG - it's a more conservative design and uses primitives > > like SHA-1 (for > > yarrow-160). I don't know how much of an impact this would be for > > network performance. > >

RE: TCP sequence numbers

1999-09-07 Thread Kris Kennaway
On Thu, 2 Sep 1999, Geoff Rehmet wrote: > > How do OpenBSD do it? > > They use arc4random(), to add a random increment. And you do ISN = C + f(state) where C is a 250KHz counter and f is your cut-down MD5? And state = {random secret, src addr, src port, dst addr, dst port, ?} I haven't had time

RE: TCP sequence numbers

1999-09-07 Thread Kris Kennaway
On Thu, 2 Sep 1999, Geoff Rehmet wrote: > > I'd expect Yarrow to be (perhaps quite a bit) slower than our existing > > PRNG - it's a more conservative design and uses primitives > > like SHA-1 (for > > yarrow-160). I don't know how much of an impact this would be for > > network performance. >

RE: TCP sequence numbers

1999-09-07 Thread Kris Kennaway
On Thu, 2 Sep 1999, Geoff Rehmet wrote: > > How do OpenBSD do it? > > They use arc4random(), to add a random increment. And you do ISN = C + f(state) where C is a 250KHz counter and f is your cut-down MD5? And state = {random secret, src addr, src port, dst addr, dst port, ?} I haven't had time

RE: TCP sequence numbers

1999-09-01 Thread Geoff Rehmet
> How do OpenBSD do it? They use arc4random(), to add a random increment. > Just curious whether you have a reference for doing this or > whether it was > an ad-hoc change. Playing with cryptographic algorithms isn't > usually a > good idea unless you're sure, as I'm sure you know. Yup - dead

RE: TCP sequence numbers

1999-09-01 Thread Geoff Rehmet
> How do OpenBSD do it? They use arc4random(), to add a random increment. > Just curious whether you have a reference for doing this or > whether it was > an ad-hoc change. Playing with cryptographic algorithms isn't > usually a > good idea unless you're sure, as I'm sure you know. Yup - dead

Re: TCP sequence numbers

1999-09-01 Thread Mark Murray
> I'd expect Yarrow to be (perhaps quite a bit) slower than our existing > PRNG - it's a more conservative design and uses primitives like SHA-1 (for > yarrow-160). I don't know how much of an impact this would be for > network performance. I will doing Yarrow-1.0A, once the IPSec stuff is around.

Re: TCP sequence numbers

1999-09-01 Thread Kris Kennaway
On Wed, 1 Sep 1999, Geoff Rehmet wrote: > After a bit of work on TCP sequence numbers, and generating initial > sequence numbers which are difficult to predict, I have put some > code together, which I belive makes the way in which FreeBSD > generates initial send sequence numbers more secure. Ho

Re: TCP sequence numbers

1999-09-01 Thread Mark Murray
> I'd expect Yarrow to be (perhaps quite a bit) slower than our existing > PRNG - it's a more conservative design and uses primitives like SHA-1 (for > yarrow-160). I don't know how much of an impact this would be for > network performance. I will doing Yarrow-1.0A, once the IPSec stuff is around

Re: TCP sequence numbers

1999-09-01 Thread Kris Kennaway
On Wed, 1 Sep 1999, Geoff Rehmet wrote: > After a bit of work on TCP sequence numbers, and generating initial > sequence numbers which are difficult to predict, I have put some > code together, which I belive makes the way in which FreeBSD > generates initial send sequence numbers more secure. H