Talk:Padding (cryptography)

Matt,

Padding is, in some sense, a higher genus of thing than both whitening and use of an IV. I was attempting to use the reference to both here as 1) an invitation to follow the link and learn something and 2) an attempt to make clear that -- at least conceptually -- both are additions (in principle arbitrary) to plaintexts or keys and so something of the same type, however different the details.

I don't see the generalisation. As I understand it, "padding" is an extension of the length of a message, such as "CAT" -> "CATXX". "Whitening" refers to scrambling the plaintext using a binary group operation with a subkey at either the initial or final round of an iterated block cipher. They are unrelated concepts, unless there's a different usage that I'm not aware of. Initialisation vectors are similarly unrelated conceptually, but I reckon its worth a "see also" since both are details that crop up when using block cipher modes.

Padding can be, and I recall that it was, used at both ends, and in the middle for that matter, of messages. In fact, Russian copulation was used as a sort of padding (though this is a stretch since no data is added) to move stereotyped ending/beginnings away from ends and begins. Not so important now when redundancy can be very effectively removed by routine use of compression. My memory of whitening differs, but... The article is looking more necessary, isn't it?

Ah, OK. (The definition I'm familiar with is noted in Schneier's Applied Cryptography, Section 15.6, if you have it to hand...) — Matt 23:43, 12 Apr 2004 (UTC)

A whitening article was, I suppose, in my future after some looking up of details I can't trust my memory to supply with fidelity. Sigh.

Go for it; I included a link from the Camellia article with that intention.

OK. But I will be taking a while with it, as I clearly can't just do it out of my head.

I suggest we reinstall mention of both whit and IV, with suitable notations as to the details of usage and such.

I think separate articles would be better.

Separate articles would indeed be good, and are obviously necessary; one exists (apparently) for IV, but I disagee that they shouldn't be mentioned here. If whitening has the meaning I thought it did. If it's your meaning, it obviously shouldn't be included here.

You might be interested to hear that I have finally had a penny drop. Seems like it took long enough. Many of the differences between you and I seem to be based in our attitude toward the reader. I keep always foremost in mind that the reader will be looking not only for facts but, being unfamiliar with the territory in many (most, nearly all, every?) case, and will benefit from explanation you deem surplus. Does this seem so to you as well? If so, do you have any suggestions as to how we might hit some middle ground on this dimension? ww 20:32, 12 Apr 2004 (UTC)

I agree that explanation that aids comprehension is good. However, some explanation can be extraneous and actually detract from the reader's understanding. I think we often disagree on what the reader is looking to find out, particularly in the encyclopedia vs textbook thing. — Matt 21:12, 12 Apr 2004 (UTC)

I guess the divergence is with 'extraneous', and with expository planning. I tie, or try to, things together to make easier the reader's road to understanding. More connections, more ways to see how things relate, more mental links, and perhaps a greater chance to understand them. Your style/inclination has fewer connections between concepts and forces the reader to do more conceptual contstruction.

I don't think the difference is textbook vs encyclopedia; even at my most extraneous, my work here is unsuited to a textbook. Having written one or two, I can speak with some authority on the inadequacy of my work here in re use in/part of textbooks.

We really should find a compromise on this, if this is the core of divergence, or you'll keep editing out my extraneous, and all will be uncomfortable. I need my extraneous to stay healthy! Seriously, at least for the occasional humourous aside, see Wetman's discussion of the place of humor here at his user page.

ww 22:44, 12 Apr 2004 (UTC)

Homer says, d'oh! example good!

C,

I'm afraid that I have to disagree with the deletion. It's true that there is a virtue in parsimony and cross linking to avoid unnecessary use of server space, there is also a virtue in writing article that will be read. Connections to things people may have heard about (Admiral Halsey, Admiral Nimitz, the return to the Philipines (never can remember, 2'l's?) are a kind of syntactic sugar which makes the medicine go down in a most (can't remember this Sound of Music lyric either). Wetware bit decay surely.

WP is not written for a specialist audience (where possible) but to inform, which means the vagaries of Average Reader are something its writers must take into account. It' probably not possible except by hwordy andwaving for such things as any flavor of string theory or most any currently researched math or ....

This article isn't one of those.

Comment?

ww 02:00, 26 September 2005 (UTC)

Moved this discussion to here from User_talk:Ciphergoth

The virtue in parsimony is that we can work on one really good account, rather than two disparate accounts that will inevitably be less good. It's possible we should write a better teaser for what is a really good story though. I love the sorts of pop-science bestsellers that add these sorts of asides to spice up this sort of information, but it's not the right tone for Wikipedia, and it doesn't work for the material about modern cryptography which is both the most relevant information to today and the section that needs the most work.

Also, of course, material about a battle in a faraway place sixty years ago will mean nothing to a lot of people and can even put them off. BTW, "A Spoonful of Sugar" is Mary Poppins :-) — ciphergoth 10:27, 26 September 2005 (UTC)