Antony Vennard

2,437 reputation

11023

bio	website	vennard.org.uk
	location	United Kingdom
	age	24
visits	member for	1 year, 10 months
	seen	May 16 at 8:39
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I am a software engineer by profession and a mathematics undergraduate in the evenings. I speak French, and I am generally interested in operating systems. My corner of the web is here and you might be interested in code I have written.

Questions? You can get in touch via my first name @ my domain name.

	2,437 reputation	bio	website	vennard.org.uk	visits	member for	1 year, 10 months
11023 badges		location	United Kingdom		seen	May 16 at 8:39

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Feb 11	comment	Counter Mode in Advanced Encryption Standard(AES) Algorithm @Bulat CTR's not all that intuitive. As you say, the plain text of the block cipher primitive is in fact shared in this case (the IV+nonce). In the NIST article, you're looking for the recommendation to use $b/2$ where $b$ is the block size of the cipher - i.e. 128 for all AES variants. They do also recommend using full-block nonces - see Paulo's comments on those.
Feb 11	comment	Counter Mode in Advanced Encryption Standard(AES) Algorithm @Bulat well, it is quite often implemented that way as recommended by NIST (Appendix B.2) and no, it does not make the encryption 64-bit. There is still a 128, 192 or 256 bit key on which the security of the system depends.
Jul 4	comment	Learnt cryptography and python. What do I do next? I'm going to close this for now as I think, all-in-all, this is just not something we can really answer for you. However, don't let that stop you asking any questions you have on crypto :)
Jun 26	comment	Getting started ...the more arguments for it, the more we can get better tools from the team, etc :)
Jun 26	comment	Getting started @Matteo well... the official answer is that we should use tag wikis like this one. As mods, we can create community wiki posts, and we've had a bit of a debate on that already. I like the idea conceptually, but I've seen it work out... badly. There's been requests to make tag wikis better too. Feel free to raise a meta post arguing your case...
Jun 25	comment	How do I protect user data at rest? I would have moved this but the OP has already cross posted: security.stackexchange.com/questions/16473/… so no need. @AAA in future, just flag for moderator attention and wait - we will get to it :)
Jun 24	comment	Getting started I've closed this as being a list-of question, which we generally don't allow here. That said, I've mentioned this to other moderators in chat, as we persistently get these questions (our first was one) and we've debated allowing them before, so this could be re-opened (and you can still see the answers given anyway).
Jun 18	comment	Why are there $ signs in my passwd file? This question on U&L might help, too: unix.stackexchange.com/questions/8229/…
Jun 15	comment	Assistance Cracking Classical Cipher I agree with the others on providing a little explanation as to how you decoded this. I don't think it needs to be a step by step guide, but a brief overview of what you did would no doubt steer the OP in the right direction :)
Jun 5	comment	How to encrypt a File using AES Algorithm? If you're looking for how to perform file encryption using a programming language, you probably want Stack overflow - a quick search finds these recommended libraries (note: ignore the ROT13 and OTP one) - and the javax.crypto docs should also help. Do remember to search there first, and post what you've tried and are not understanding - as it stands, this will be closed on SO too :)
May 30	comment	Applying multiple hash functions to improve security? I've closed this for now as a duplicate of the other question, the discussion on there should help I hope :) If your question is different (and I'm just not seeing it), do feel free to edit/reply to me here and we can look at re-opening it.
May 25	comment	After implementing a novel encryption algorithm, how would one go about analyzing its security or get help from others in doing so? Guys, just a friendly note - if you're providing an answer to a question, use the answer box, not the comment box. Big hint - some of these comments are semi answers! :)
May 24	comment	Why does my implementation of CBC mode only decrypt the first block correctly? Hello - this is really off topic here and belongs on Stack Overflow; however, before I migrate it there it could really do with an edit - have you nailed down exactly where the issue is? SO likely don't need all of the code you've posted. If you flag when you've had a look at some of SO's questions and edited yours, I'll be able to migrate it there. Please don't cross post :)
May 23	comment	Is it secure to use the hash of key as the IV in AES encryption? Welcome to crypto; your question was migrated here by the SO mods as it is a better fit here. Feel free to register here to receive notification of your responses :)
May 16	comment	ECIES protocol - what does the \|\| operation mean? @eXPi yep. It also means, in this case, that the output of the KDF is split into two parts - one part for each key.
May 16	comment	Assistance Cracking Classical Cipher Also, if you feel the FAQ can be improved, do weigh in on meta :)
May 16	comment	Assistance Cracking Classical Cipher As I wrote that FAQ, I'll weigh in with what I think - the "challenge people to decode something" was meant to deal with "please decode XYZ bet you can't !11!!1"-type questions, of which we've had a few. It's not meant to discourage questions which are a decent attempt at cryptanalysis, although I think they do need to be reasonably answerable. As is, I think we could do with as much information as you can give - perhaps the results of your frequency analysis, for example? However, I don't see the need to fire a mod close vote at it, although the community or other mods may disagree :)
May 12	comment	Is XOR in a CBC-like mode secure? I went for CBC-like as that's the best I could explain it, as opposed to just "this algorithm", but feel free to improve, anyone. If I can come up with a better one, I will, when it's not so late :)
May 12	comment	Is XOR in a CBC-like mode secure? Hello, welcome to crypto; I edited your title to be a little more descriptive (I realise you probably didn't know what to put as the title :)) - if you want to improve it, or roll it back, there is an edit link directly underneath your question which you can use at any time :)
May 12	comment	Academic papers on GPU password cracking? @Ian I'm slightly confused, as it isn't you asking the question - however, c'mon, you have 22k rep on SO and you're telling me you can't see why we've closed this as list-inviting? "Are there any implementations of sha1 in C#?" is that a good question? No. Now, there is the potential for this to be a good question by asking about what you want to know reading those papers - but not asking for a yes/no, and not asking for some papers.