D.W.

8,825 reputation

828

bio	website
	location
	age
visits	member for	1 year, 10 months
	seen	2 days ago
stats	profile views	140

	8,825 reputation	bio	website		visits	member for	1 year, 10 months
828 badges		location			seen	2 days ago

summary answers questions tags badges favorites bounties reputation activity

974 Actions

suggestions reviews revisions comments badges posts accepts all

Jan 31	comment	Discrete log analog of ECM factoring algorithm? @CrisStringfellow, thanks for the thought, but that is not correct: your method does not work. The error in your reasoning is in the part where you say "which is by definition smaller". To discover the error for yourself, try writing out the exact reduction: an algorithm which computes the discrete logarithm, given a magical black box that factors any integer of your choice. Then, try to analyze the running time of your scheme. I think you'll find your method doesn't work.
Jan 25	asked	Discrete log analog of ECM factoring algorithm?
Jan 24	comment	Are there hash algorithms with variable length output? @BMiner, sometimes some crypto libraries will generate the IV for you and include the IV in the ciphertext. In other words, when you encrypt, you pass in a key and a message, and you get back a ciphertext, where the ciphertext includes the IV somewhere in it. If your library is like that, you need to remove the IV (and make sure that the IV always starts at 0). This gets easier if you implement AES-CTR yourself, so you can force it to start at IV 0 and make sure that the output only includes the generated pseudorandom stream (and not the IV).
Jan 23	revised	Initialize a PRNG with a password added 36 characters in body
Jan 23	comment	Initialize a PRNG with a password @Gilles, in principle, I agree, but passwords almost never have enough entropy (particularly if you need to ask).
Jan 23	revised	Initialize a PRNG with a password deleted 431 characters in body
Jan 23	comment	Initialize a PRNG with a password @Gilles, you are right. My mistake. Thank you.
Jan 23	answered	Initialize a PRNG with a password
Jan 23	comment	Non-cryptographic hash function as MAC for stream ciphers Oops, you are absolutely right, it's right up there, I'm just blind! Deleting my earlier bogus comment. Sorry about the noise.
Jan 23	revised	Are there hash algorithms with variable length output? added 173 characters in body
Jan 23	comment	Are there hash algorithms with variable length output? @BMiner, it depends upon the mode. For CBC mode, this will work as long as you make sure to first remove the IV (since the IV won't be random), and take the first $b$ bits of the remaining ciphertext. I would expect something similar to hold for other reasonable modes too but I haven't thought about it carefully.
Jan 22	revised	Reference papers for protocol proving added 300 characters in body
Jan 22	answered	Reference papers for protocol proving
Jan 19	comment	Is it safe to use RSA as a proof-of-work system? I think this scheme is broken; see my answer for details.
Jan 19	comment	Is it safe to use RSA as a proof-of-work system? I just realized the proposed scheme seems to be broken. (A key hint comes in the sentence in this answer: "you gave [the client] $d$ and hence the factorization of $n$". However I don't think this answer realized the full implications of this.) Therefore, this answer's conclusion (that the scheme is OK) seems wrong. See my answer for an explanation of the attack and why this proposed scheme should not be used.
Jan 19	revised	Is it safe to use RSA as a proof-of-work system? added 1235 characters in body
Jan 19	revised	Is it safe to use RSA as a proof-of-work system? added 1235 characters in body
Jan 19	answered	Is it safe to use RSA as a proof-of-work system?
Jan 19	answered	Many time pad attack
Jan 19	comment	Is it safe to use RSA as a proof-of-work system? I should also ask: Why do you want to use RSA in particular, as opposed to any of the many other proof-of-work systems? It is possible there might be other, even better ways to achieve your requirements, depending upon what your requirements may be. I don't know if that interests you or not.