Re: Warning! New cryptographic modes!

2009-05-21 Thread Jerry Leichter
On May 11, 2009, at 7:06 PM, silky wrote: How about this. When you modify a file, the backup system attempts to see if it can summarise your modifications into a file that is, say, less then 50% of the file size. So if you modify a 10kb text file and change only the first word, it will

Re: Warning! New cryptographic modes!

2009-05-21 Thread silky
On Tue, May 12, 2009 at 10:39 AM, Jerry Leichter leich...@lrw.com wrote: On May 11, 2009, at 8:27 PM, silky wrote: The local version needs access to the last committed file (to compare the changes) and the server version only keeps the 'base' file and the 'changes' subsets. a)  What's a

Re: Warning! New cryptographic modes!

2009-05-21 Thread Jerry Leichter
On May 11, 2009, at 7:08 PM, Matt Ball wrote: Practically, to make this work, you'd want to look at the solutions that support 'data deduplication' (see http://en.wikipedia.org/wiki/Data_deduplication). These techniques typically break the data into variable length 'chunks', and de-duplicate by

Re: Warning! New cryptographic modes!

2009-05-21 Thread silky
How about this. When you modify a file, the backup system attempts to see if it can summarise your modifications into a file that is, say, less then 50% of the file size. So if you modify a 10kb text file and change only the first word, it will encrypt that component (the word you changed) on

Fwd: cryptohippie: the electronic police state ranking 2008

2009-05-21 Thread R.A. Hettinga
Begin forwarded message: From: Eugen Leitl eu...@leitl.org Date: May 12, 2009 11:51:13 AM GMT-04:00 To: i...@postbiota.org, cypherpu...@al-qaeda.net, t...@postbiota.org Subject: cryptohippie: the electronic police state ranking 2008 https://secure.cryptohippie.com/pubs/EPS-2008.pdf The

Re: Warning! New cryptographic modes!

2009-05-21 Thread Matt Ball
On Mon, May 11, 2009 at 2:54 PM, Jerry Leichter leich...@lrw.com wrote: On May 11, 2009, at 2:16 PM, Roland Dowdeswell wrote: On 1241996128 seconds since the Beginning of the UNIX epoch Jerry Leichter wrote: I'm not convinced that a stream cipher is appropriate here because if you change the

Re: Warning! New cryptographic modes!

2009-05-21 Thread James A. Donald
Jerry Leichter wrote: Consider first just updates. Then you have exactly the same problem as for disk encryption: You want to limit the changes needed in the encrypted image to more or less the size of the change to the underlying data. Generally, we assume that the size of the encrypted

Re: Warning! New cryptographic modes!

2009-05-21 Thread Darren J Moffat
Jerry Leichter wrote: To support insertions or deletions of full blocks, you can't make the block encryption depend on the block position in the file, since that's subject to change. For a disk encryptor that can't add data to the file, that's a killer; for an rsync pre-processor, it's no big

Re: Warning! New cryptographic modes!

2009-05-21 Thread silky
On Tue, May 12, 2009 at 10:22 AM, Jerry Leichter leich...@lrw.com wrote: On May 11, 2009, at 7:06 PM, silky wrote: How about this. When you modify a file, the backup system attempts to see if it can summarise your modifications into a file that is, say, less then 50% of the file size.

Re: Solving password problems one at a time, Re: The password-reset paradox

2009-05-21 Thread Anne Lynn Wheeler
On 05/09/09 07:33, Jerry Leichter wrote: I had a discussion with a guy at a company that was proposing to create secure credit cards by embedding a chip in the card and replacing some number of digits with an LCD display. The card would generate a unique card number for you when needed. They

Re: Significance of Schnorr's Factoring Integers in Polynomial Time?

2009-05-21 Thread Markus Rückert
I have three brief comments. 1) The main theorem assumes that we can find a vector of length ≤ \sqrt{2eπ} n^b λ_1 In general, this is not possible in polynomial time, esp. for small b. 2) NEW ENUM takes time exponential in n unless b is very small such that n^b is eliminated by rd(L). 3) GSA

A Service to Prove You are Really You

2009-05-21 Thread Ali, Saqib
On the Internet, nobody knows you’re a dog, as the New Yorker cartoon famously said. But what if, while you are surfing, you want to prove your pedigree? Equifax, the big credit agency that already knows more about your flea count than you do, wants to help. :

Re: Warning! New cryptographic modes!

2009-05-21 Thread Jerry Leichter
On May 11, 2009, at 8:27 PM, silky wrote: The local version needs access to the last committed file (to compare the changes) and the server version only keeps the 'base' file and the 'changes' subsets. a) What's a committed file. b) As in my response to Victor's message, note that you can't

Re: Warning! New cryptographic modes!

2009-05-21 Thread Jon Callas
I'd use a tweakable mode like EME-star (also EME*) that is designed for something like this. It would also work with 512-byte blocks. Jon - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography

visualizing modes of operation

2009-05-21 Thread Steven M. Bellovin
http://www.cryptosmith.com/archives/621 --Steve Bellovin, http://www.cs.columbia.edu/~smb - The Cryptography Mailing List Unsubscribe by sending unsubscribe cryptography to majord...@metzdowd.com

[fc-announce] CF Workshop Proposals for FC10. Deadline: June 15, 2009

2009-05-21 Thread R.A. Hettinga
Begin forwarded message: Resent-From: r...@unipay.nl From: Pino Caballero pcaba...@ull.es Date: May 15, 2009 7:02:54 AM GMT-04:00 Resent-To: fc-annou...@ifca.ai To: pcaba...@ull.es Subject: [fc-announce] CF Workshop Proposals for FC10. Deadline: June 15, 2009 We apologize in advance if