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location Wellington, New Zealand
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visits member for 2 years, 6 months
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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.


Jan
19
answered Using CBC with a fixed IV and a random first plaintext block
Jan
19
revised Is it safe to use RSA as a proof-of-work system?
fixed complexities
Jan
19
comment AES CBC mode or AES CTR mode recommended?
Please show some research effort in your questions.. and they can both be made just as secure if done right. They both have their pros and cons and target different uses.
Jan
19
comment Is it safe to use RSA as a proof-of-work system?
@D.W. Fixed, thank you.
Jan
19
revised Is it safe to use RSA as a proof-of-work system?
fixed error
Jan
19
revised Is it safe to use RSA as a proof-of-work system?
better latex
Jan
19
answered estimate of time required to crack sha512crypt password with JtR + OpenCL
Jan
19
comment Is it safe to use RSA as a proof-of-work system?
@DavidSchwartz Your proof of work scheme can be parallelized.
Jan
19
answered Is it safe to use RSA as a proof-of-work system?
Jan
19
reviewed Leave Open LFSR for small numbers with large periods
Jan
19
reviewed Leave Open Many time pad attack
Jan
18
comment Difference between Rijndael 128 / 256 blocksize implementations? (and impact of block size in general)
At least it isn't a problem for encryption. If you wanted to build a hash function from AES (theoretically speaking - in real life you don't do that and use a primitive designed to that end) you'd need to pick a high rate compression function to compensate for the small block size.
Jan
17
comment What does modular inversion mean?
This really should have gone to Math.SE instead, it's purely a number-theoretical computation problem. Its relation to cryptography is incidental at best and is unlikely to ever help someone who's specifically studying the cited paper.
Jan
16
comment LFSR for small numbers with large periods
Understood, so you want to switch to a different permutation when the first one is exhausted and so on. Do you have memory requirements? Can you store up to 32 values for a shuffle?
Jan
16
comment LFSR for small numbers with large periods
But a 5-bit pseudorandom permutation always has a period of $2^5 = 32$ (well, excluding the zero, since this is an LSFR). After that a number will repeat due to the pigeonhole principle. This is where I'm confused.
Jan
16
comment LFSR for small numbers with large periods
I see what you mean, but you said "single numbers don't repeat" which would imply you are looking for a pseudorandom permutation of $\mathbb{Z} / 2^5 \mathbb{Z}$ (which can be achieved using a Fisher-Yates shuffle using the 16-bit LSFR). Just truncating off bits wouldn't work here, obviously. Or did I misunderstand you? What you want is, to convert a 16-bit pseudorandom permutation to a 5-bit pseudorandom permutation, am I correct?
Jan
16
comment LFSR for small numbers with large periods
I don't understand the first requirement - why shouldn't those smaller numbers repeat? And since they must not repeat, doesn't this sort of imply the period needs to be reduced to $2^5$ from $2^{16}$, contradicting your second requirement?
Jan
15
reviewed Looks OK Is the One Time Pad (OTP) considered a cryptographic hash function?
Jan
12
reviewed Looks OK Is the One Time Pad (OTP) considered a cryptographic hash function?
Jan
11
comment How and why can a decryption program tell me that a key is incorrect?
Note most symmetric padding schemes will fail to provide integrity with probability $\frac{1}{256}$ in the worst case, so it's really just a sanity check and not a substitute to proper integrity checking.