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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.


Jul
6
reviewed Reject Cryptographic Challenge: How to Say Something Confidentially to Snowden?
Jul
6
comment Securely generating passwords based on a secret and a public identifier
@GeorgeBashi I would say that is okay. HMAC is guaranteed not to leak any information about the input, so it should be safe to feed it into HMAC while still using the keypair as usual. This is assuming the private key has enough entropy e.g. is long enough to avoid being brute-forced, which is hopefully the case here. I'm not sure I understand what you mean by "certificates" though.
Jul
4
reviewed Approve constructing QR-like one way function
Jul
4
comment Encryption schemes and pseudorandom permutations
The IV is conventionally part of the output but not of the input (which is why it's called a randomized encryption scheme - randomization is a property of the primitive, else it would still be deterministic). Anyway, I think I understand better, you want to ask to what extent a PRP can be modelled as PRF, since their security properties overlap, right?. One will necessarily need to instantiate those with at least some concrete security parameters such as input/output length. For instance, you are correct that a 128-bit PRP cannot be distinguished from a PRF, but a 64-bit PRP certainly can.
Jul
4
comment Encryption schemes and pseudorandom permutations
Did you mean a pseudorandom permutation? A pseudorandom function isn't very useful for encryption since it isn't invertible (so it's not possible to decrypt). Also, consider that an encryption scheme returning an output exactly as long as its input must necessarily be deterministic.. what does that imply about some of its security properties?
Jul
4
answered Securely generating passwords based on a secret and a public identifier
Jul
4
reviewed Approve length-extension tag wiki excerpt
Jul
4
reviewed Approve padding-oracle tag wiki excerpt
Jul
4
reviewed Approve length-extension tag wiki
Jul
4
reviewed Approve padding-oracle tag wiki
Jul
4
comment Cryptographic Challenge: How to Say Something Confidentially to Snowden?
Isn't objective #2 self-contradictory?
Jul
3
comment constructing QR-like one way function
I think you made a mistake, $x^2 \mod p$ is not (generally) one-way, there are efficient algorithms to take modular square roots modulo prime numbers (it's much harder for composites, though). Did you mean $a^{\frac{p - 1}{2}} = \binom{a}{p}$ which then obviously lacks collision resistance..
Jun
30
comment Why is “mod(n)” so central to most aspects of cryptography?
@nightcracker Unless you count bitwise modulo's, which are still there but just hidden and implied :p (though I agree with you that symmetric cryptography doesn't need as much number-theoretic baggage - it just needs to be able to throw bits around efficiently)
Jun
30
revised Integer factorization via geometric mean problem
added 546 characters in body
Jun
30
answered Integer factorization via geometric mean problem
Jun
30
comment Integer factorization via geometric mean problem
What makes you think that arbitrarily truncating $\sqrt{c} \times 10^i$ for any $i$ will give a meaningful integer with the properties you describe? The reason it works for small numbers is that some $i$ ends up giving a factor by chance, obviously that doesn't happen for larger integers. I don't follow your geometric mean argument - how does it relate to multiplying the mean by a power of 10? Why not a power of 2? What's so special about 10? (I think this is where your argument breaks down - $g$ is irrational so you'll never get an integer, perhaps you were thinking of continued fractions?)
Jun
29
comment Proof of work for determining whether a number is prime?
Why not select the primes yourself and create a challenge using that? That way it would be trivial for you to verify if there is (at least) a prime falling inside a given range. Or is this a distributed proof of work scheme?
Jun
24
comment Map Bytes to Number
A more efficient approach is to take the problem modulo 65536 and divide by 6 when less than 60000, you will waste less entropy this way. This question is actually a duplicate of a couple crypto.SE questions, in particular crypto.stackexchange.com/questions/5708/… and crypto.stackexchange.com/questions/6175/…
Jun
24
reviewed Satisfactory Polynomial multiplication and division in2^128
Jun
24
reviewed Satisfactory Is Base64(SHA1(GUID)) still unique like the original GUID?