Talk:Stream cipher

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To-do list for Stream cipher:	edit · history · watch · refresh
Add a simple diagram of synchronous stream cipher operation vs asynchronous Mention Shrinking generator, Self-shrinking generator Discuss use of LFSRs in stream ciphers (non-linear combining function; non-linear filtering; clocked LFSRs) Discuss relationship with OTP/Vernam cipher

Contents 1 Speeds 2 Errors 3 Military 4 Comparison table 5 Grammar in second sentence 6 Question 7 smallest unit

[edit] Speeds

I am changing the sentence "Stream ciphers typically execute at a higher speed in hardware but a much slower speed in software than block ciphers." because it isn't generally true. RC4, for example, is one of the fastest strong ciphers available in software. --agr 18:26, 17 Nov 2004 (UTC)

[edit] Errors

The patent indicated in the link actually points to a releasable pin. I can't find the correct patent, but maybe some clever pedian can. —The preceding unsigned comment was added by 198.97.67.57 (talk) 16:58, 30 January 2007 (UTC).

Yes indeed. I took the liberty of removing reference (U.S. Patent 2,405,400 ), because it was not valid. Whoever finds the correct patent number, feel free to insert the reference back.

[edit] Military

The sentence

Another advantage of stream ciphers in military cryptography is that the cipher stream can be generated in a separate box that is subject to strict security measures and fed to other devices, e.g. a radio set, which will perform the xor operation as part of their function. The latter device can then be designed and used in less stringent environments.

looks questionable to me--any device that sees plaintext has to be designed stringently. See Red-black separation. I'd like to remove this sentence unless someone objects. Phr 03:37, 9 April 2006 (UTC)

[edit] Comparison table

I wonder if a comparison table is a good idea. We found that trying to maintain one for ESTREAM was a pretty fraught business, especially when (as is the case with Py (cipher) there's dispute about the validity of an attack. And unlike with with ESTREAM, here the table may grow without bound.

I think it should list only ciphers that are widely used: RC4, A5/1, A5/2 etc.

On a minor note, the table suggests that there are linear cryptanalytic attacks on Salsa20. I'm unaware of any published, unless you mean the papers by Li An-Ping which never made sense have been pretty thoroughly shredded. — ciphergoth 05:51, 7 September 2006 (UTC)

Pretty table. Does the color coding mean anything? There's no legend for cell color. -Kvng 16:24, 28 September 2006 (UTC)

I removed the cite of Jean-Phillip Aumasson's distinguishing attack on ISAAC, because it doesn't work. And marked ISAAC as N/A for an initialization vector, since having already seeded ISAAC doesn't give you an easier reseeding algorithm. I doubt that RC4 really has any IV algorithm either, but didn't mark that N/A because I wasn't sure. 71.164.0.155 09:18, 4 January 2007 (UTC) Bob Jenkins

[edit] Grammar in second sentence

I changed "In a stream cipher the plaintext digits are encrypted one at a time, and in which the transformation of successive digits varies during the encryption." to "In a stream cipher the plaintext digits are encrypted one at a time, and the transformation of successive digits varies during the encryption." because it didn't appear to make sense. If I was wrong, can someone who knows things please fix it? Bitwiseb 20:43, 7 November 2007 (UTC)

[edit] Question

how do you create a hash function from a stream cipher? —Preceding unsigned comment added by 131.111.8.96 (talk) 22:39, 22 January 2008 (UTC)

[edit] smallest unit

..while stream ciphers eliminate this issue by naturally operating on the smallest unit that can be transmitted (usually bytes).

isn't a bit the smallest unit? stream ciphers can operate bitwise. —Preceding unsigned comment added by 147.86.212.162 (talk) 08:28, 10 June 2008 (UTC)