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location Wellington, New Zealand
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visits member for 2 years, 3 months
seen 7 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.


Nov
30
comment Does a playlist of songs or movies mixed together contain enough random enough for OTP key material?
@zuallauz "If the whole entropy is generated by the user, e.g. by moving my mouse around, tapping on the keyboard, pulling in data from /dev/random and even plugging in a random number generator dongle, how long would it take to make 200MB of usable random key material?" A very long time, but that is the price of unconditional security. Using existing data cannot by definition be considered an appropriate source of entropy (and especially not for a one-time-pad), no matter how ludicrously large this existing data is. It is the very definition of entropy.
Nov
30
comment Does a playlist of songs or movies mixed together contain enough random enough for OTP key material?
@zuallauz Then at this point, explain why not just use the entropy generated by the user to directly create the pad, instead of going through "tv/movie data"?
Nov
29
comment Does a playlist of songs or movies mixed together contain enough random enough for OTP key material?
@zuallauz 620 million is nothing in cryptography. And as I highlighted in my answer, the order of your song combination is irrelevant, as they are being concatenated - I can try and figure the position of each one, one after the other. I agree it wouldn't be easy (in human terms) but it is not a one-time-pad. It's just an overly complex and fragile cryptosystem (really hard to analyze, too). As for your second point, the content of songs are not random (as much as you would like them to be), so you cannot apply the equiprobable plaintext argument.
Nov
29
revised Does a playlist of songs or movies mixed together contain enough random enough for OTP key material?
added 101 characters in body
Nov
29
answered Does a playlist of songs or movies mixed together contain enough random enough for OTP key material?
Nov
28
reviewed Reviewed Necessity for finite field arithmetic and the prime number p in Shamir's Secret Sharing Scheme
Nov
27
comment How to prove membership of a list without disclosing the list members?
What does hash(a, b, c) mean? Is it just hash(a || b || c), or some other, possibly keyed construction?
Nov
27
awarded  Custodian
Nov
27
reviewed Reviewed Can ECDSA signatures be safely made “deterministic”?
Nov
27
reviewed Reviewed How should I calculate the entropy of a password?
Nov
27
reviewed Reviewed How key materials are generated in SSL V3 from master secret
Nov
27
comment Cracking WWII-era codes - code found on a pigeon's leg in Surrey
Well in that case, it's not a "one-time-pad" anymore. I see your point though. It could be anything since we don't know which encryption algorithm was used.
Nov
27
comment Cracking WWII-era codes - code found on a pigeon's leg in Surrey
The definition of the one-time-pad is that the pad is exactly as long as the message. The pad cannot repeat (that is the basis of the security proof of the one-time-pad). On the other hand, if the same pad is used twice to encrypt two different messages, then yes, you are in trouble. Used properly (which includes: do not reuse the pad), the one-time-pad is unconditionally secure - it cannot be "broken" without knowledge of the pad (which is fully random and as long as the message it encrypts). So unless you can find the pad scribbled somewhere in some german bunker, no, you are screwed.
Nov
27
reviewed Reviewed Cracking WWII-era codes - code found on a pigeon's leg in Surrey
Nov
27
comment Cracking WWII-era codes - code found on a pigeon's leg in Surrey
If the pad is a short sequence that is repeated, or if it's taken from a book, then it's not a one-time pad.
Nov
27
reviewed Reviewed Is the AES encryption scheme CPA secure?
Nov
27
reviewed Reviewed Looking for examples for “proof by reduction”
Nov
27
comment Learning cryptography using a FPGA
You could take a look at the scrypt KDF, which is specifically designed to defeat FPGA brute-forcing as it requires large amounts of on-chip memory for each KDF invocation.
Nov
25
reviewed Approve suggested edit on Looking for examples for “proof by reduction”
Nov
24
reviewed Reviewed Cracking the Beaufort cipher