405 reputation
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location Wellington, New Zealand
age
visits member for 3 years, 3 months
seen 4 hours ago

I am an undergraduate computer science and mathematics student in New Zealand. My fields of interest are computer graphics, in particular the physics of light transport, and to some extent cryptography, as well as programming and software development in general.


Mar
27
comment Can 'cracked' product keys harm the user in any way?
@StrongBad That's assuming you can reliably detect that a cracked key was used.. delete even a single legitimate user's hard drive by error and your product is finished. Seems like a pretty big risk for very little gain.
Mar
17
comment Is using the concatenation of multiple hash algorithms more secure?
@supercat H2(H1(x)) is called composition, not concatenation. I've never heard it referred to as concatenation either.
Feb
12
comment Can you say that since one time pad encryption is unbreakable, it is the best if used properly?
@Xander Fair enough
Feb
12
comment Can you say that since one time pad encryption is unbreakable, it is the best if used properly?
@Xander My point was that the OP is only talking about the one-time-pad because that's what he knows, and isn't aware either that authentication is important or that unconditionally secure MAC's exist (or both). If he were, he would not have excluded it from his question, since encryption without authentication is useless as you have explained in your answer, therefore adding a note that the authentication problem is not a fundamental problem with unconditionally secure schemes seems in order, as opposed to simply dismissing the option (irrespective of how viable such schemes are in practice).
Feb
11
comment Can you say that since one time pad encryption is unbreakable, it is the best if used properly?
This answer fails to mention that there are information-theoretically secure integrity schemes, e.g. Wegman-Carter, and at least in principle you could bundle it with the OTP in a sort of information-theoretic cryptosystem - it's good to mention that integrity/authentication is essential, but then quickly taking a shortcut to "easy to use authenticated ciphers" sounds very much like avoiding the question in the context of "why isn't one-time-pad encryption [read: information-theoretic security] the best"; OP is really asking about unconditionally secure cryptosystems, not OTP specifically.
Oct
14
comment Are single case alphanumeric passwords the most user friendly?
Jesus christ, people. 20 hexadecimal characters. It's not that hard to remember a couple of them, seriously, especially with muscle memory. And you can use a password manager with a strong passphrase, there. In my experience, a long password made up from a reasonably small alphabet is INFINITELY easier to remember than a short one made up from a huge alphabet.
Oct
11
comment Do passphrases need to be run through PBKDF2? Almost impossible to brute force?
How would you enforce the usage of a strong passphrase in general? The whole raison d'etre of password-based KDF's is to compensate for poorly chosen passwords. If you take that out of the equation, by ensuring your passphrase has as much entropy as a typical key, then you vacuously don't need a PBKDF, only a plain KDF...
Jun
30
comment How can a passphrase with 256 bits of entropy practically be constructed & memorized?
@NateKerkhofs You probably don't want to be typing that master passphrase (it is your master passphrase, right? if you're remembering one poem per website you frequent, well, hats off) into a website anyway. If you're looking for that level of security a password manager is almost certainly in order (but still, a pain to type in either way).
Jun
30
comment How can a passphrase with 256 bits of entropy practically be constructed & memorized?
Now for the next question: how to type in a 37-word poem into a prompt discreetly and in a timely manner without typos in a variety of environments :-)
May
14
comment Is saving a list of passwords in Acrobat XI with 256bit AES encryption as secure as something like KeePass?
"Is there any reason not to do this?" You mean apart from the fact that a PDF editor (and, more importantly, viewer) is not designed to be used as a password manager? Who's to say some viewers don't cache PDF files into a temporary folder for history/faster viewing/whatever? You wanted this to have access to your passwords on public/semipublic computers? Boom, there go all your passwords. If it's a private computer/phone, why not use a password manager (they can sync too, you know)? Basically, it's a bad idea, even if the crypto is sound (and the crypto itself is rarely the problem).
Apr
12
comment How difficult to crack keepass master password?
@Pacerier Except most of these are not practical yet. If you are able to predict the future evolution of computing power with exotic hardware, then you can certainly make a good estimate of what constitutes a "hard problem". Most of us can't.
Feb
26
comment Why are salted hashes more secure?
@tylerl Thank you
Feb
24
comment Is using SHA-512 for storing passwords tolerable?
@SnakeDoc It is cryptographically secure, it's just not designed to be a password-based KDF.
Feb
22
comment Why are salted hashes more secure?
Could you please add a final paragraph about key stretching and using a proper KDF, otherwise this post is going to spawn yet more sha1(salt || pwd) schemes by users who only read this answer and went to do their thing. I know it's technically off-topic but we really need to fight this by trying not to suggest to use this directly.
Feb
8
comment Bad practice to have a “god” password?
This account has been terminated for the following reason: unauthorized access to donuts.
Jan
29
comment My home PC was hacked and accessed my bank! Advice on next steps?
s/not find/find
Jan
18
comment What is the excellence of RSA vs my algorithm
It's quite easy to obtain d from e. Just run the "test" function on it and get a (somehow) valid "d" for it. Oops? What does your algorithm do? It's nonsense as it is now.
Jan
14
comment Forward secrecy for kids
@ewanm89 It gets rather tedious doing it by hand for 1024+ bit parameters.
Dec
27
comment How to change TEA round count?
Well, in all fairness, now that I read it again, my comment was somewhat tautological. Glad you found the problem though!
Dec
27
comment How to change TEA round count?
There's probably something else you didn't change that's still assuming 32 rounds are used and that's throwing decryption off.