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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.


Jun
24
reviewed Satisfactory Is Base64(SHA1(GUID)) still unique like the original GUID?
Jun
24
reviewed Excellent AES plaintext is smaller than 128 bits - how to expand?
Jun
24
reviewed Satisfactory How does the birthday attack work in AUTH and UF-CMA games?
Jun
24
reviewed Satisfactory Injecting salt into PyCrypto KDF - useful?
Jun
24
comment If we can find prime numbers larger than 17 milion digits, why can't we find all 1024bit primes?
@user129789 Those numbers are so huge that no amount of optimization can make this approach feasible. Literally, you would need to store around $2^{750}$ primes into a single atom, which is an unimaginably large number, and for all intents and purposes infinite. Tylo, your calculation is wrong, by the way, that should be $2^{1013.5 - 265.75}$ (just about 744 orders of magnitude off :p)
Jun
24
comment If we can find prime numbers larger than 17 milion digits, why can't we find all 1024bit primes?
@user129789 Even if we assumed that you could calculate all those $2^{1024}$ primes - never mind all their products pairwise, to make a huge lookup table - instantly (that is ludicrous but let us imagine). How much space would you need to store them all (1024 bits per prime)?
Jun
19
comment What is U2FsdGVkX1?
And just for completeness (since the quote only answers half of the question) starting the files with "Salted__" does not give away information beyond the fact that the file was encrypted with (or at least for) OpenSSL, which is assumed to not be secret. So it isn't insecure.
Jun
19
comment Is a small size block cipher usable?
For 32-bit block sizes I think a few hundred megabytes of output should be sufficient to distinguish between a CTR keystream and a random function, actually, assuming the plaintext has sufficient structure.
Jun
19
revised Is there a hash function which has no collisions?
added 6 characters in body
Jun
19
comment Is there a hash function which has no collisions?
@improv32 I understand. No, there isn't, under the standard definition of "hash function". But there are certainly one-way, collision-free functions, as CodesInChaos mentioned in a comment.
Jun
19
revised Is there a hash function which has no collisions?
added 374 characters in body
Jun
19
comment Is there a hash function which has no collisions?
@improv32 Hash functions can do that in what is called a commitment scheme. Why do you require the "no collision" property? Or did you really mean, "with a negligibly low chance of collision, which then is what cryptographic hash functions are for in that while there are infinitely many collisions, it is very hard to find one either accidentally or on purpose"?
Jun
19
revised Is there a hash function which has no collisions?
added 688 characters in body
Jun
19
answered Is there a hash function which has no collisions?
Jun
18
reviewed Approve suggested edit on prime-numbers tag wiki
Jun
18
comment How to build an electro-mechanical public key cipher machine?
@Manuel I agree those would be better fits for such computers.
Jun
16
revised How to build an electro-mechanical public key cipher machine?
edited tags
Jun
16
comment How to build an electro-mechanical public key cipher machine?
I don't see why not. Even mechanical computers were Turing-complete in that they could be built to accommodate any series of instructions, so even elliptic curve cryptography could theoretically be built from vacuum tubes and rotors. Now, as for efficiency..
Jun
14
comment Recommended authenticated stream cipher for minimum overhead?
If it were possible to have zero authentication overhead, authenticated encryption schemes would already be doing it. You won't find your solution at this low a level, you need to go up a notch and design your system around minimizing overhead.
Jun
14
comment Recommended authenticated stream cipher for minimum overhead?
Yes, of course. But, no, a MAC always requires extra information. Think about it - if you have X bits of plaintext to encrypt and authenticate, and Y bits of output, at the very least X = Y to ensure correct decryption (pigeonhole principle) which leaves nothing for authentication. So Y > X. So, no, any authentication mechanism will always add a few bytes of overhead to store the fingerprint. So your options are in making the fingerprint smaller (not ideal for obvious reasons) or authenticating more data per fingerprint.