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seen Nov 10 at 4:37

Nov
10
comment repeating-key xor and hamming distance
Hi @GabeHollombe, for new questions, I recommend you post a new question. But the short answer is: yes. If you guessed the key length correctly, you're looking at $\text{wt}(X \oplus K \oplus Y \oplus K) = \text{wt}(X \oplus Y)$, which is 2-3 bits. If you guessed it incorrectly, you're looking at $\text{wt}(X \oplus K \oplus Y \oplus K')$, which is about 3 bits (here all of $X,Y,K,K'$ are independently distributed English ASCII letters). ASCII lowercase letters are 0x61 to 0x7A, so the xor of four of those is close to uniform on its low 6 bits, and thus has 3 bits set on average.
Nov
9
comment Which attacks are possible against raw/textbook RSA?
What research have you done? There's lots written on this. See, e.g., Dan Boneh's survey. Or, search on "textbook RSA" on this site (or elsewhere) and you'll find many references.
Nov
3
comment Is splitting AES ecrypted data safe?
What research have you done? Have you looked at the other questions marked secret-sharing? Why are you considering this approach rather than one of the standard schemes that are mentioned in those other questions, such as Shamir secret sharing?
Oct
24
comment Mounting internal FileVault encrypted drive in 10.9 OS X in Recovery Mode without unlocking it; Passware brute-force
I suggest clicking "flag" to ask the moderators to migrate this to Ask Different.SE, as this question is more about how to use Apple software than about cryptographic concepts.
Oct
14
comment How costly is to find millions of large prime numbers for RSA?
@user153465, that's because pseudorandom generators require their seed to be uniformly distributed. The way to extract the entropy in a value and make it look uniformly distributed is to use a hash function. Justifying that would probably require some non-trivial cryptographic knowledge (e.g., the random oracle model, definitions of security of a PRG, and so on). Or, you can just trust me that this is a competently engineered cryptographic construction.
Oct
13
comment Weak key schedule IDEA
Nova, OK, I'm sympathetic. But the papers that describe the design of IDEA are cited in "Weak Keys for IDEA", which you link to in your post; see the introduction and references [1,2]. So, you can check for yourself whether the designers said anything on this topic in those papers. Are you familiar with how to do a literature search?
Oct
13
comment How to compute the decompositions used in fast FHE bootstrapping?
Are you really asking for an algorithm to represent an integer $x$ in base $b$? That's standard stuff. Have I misunderstood your question?
Oct
13
comment Weak key schedule IDEA
Nova, well, OK, what research have you done? Have you searched on Google Scholar? If that's what you want to know, you could edit your question to ask "Is there a paper explaining the design decisions that went into IDEA?". But, truthfully, that's not a good question -- the answer is yes there's such a paper and you can find your own using Google Scholar, so asking such a question would be a poor question because it would indicate you haven't done your research.
Oct
13
comment Weak key schedule IDEA
How could anyone other than the designers of IDEA possibly answer this question with any degree of certainty? I suggest you edit the question to ask a technical question, one where answers can be supported by facts and reasoning and evidence, not a question that invites speculation (asks us to read the mind of the designers of IDEA).
Oct
13
comment Isn't 'exponent' only present in MSME equations in Groth-Sahai framework?
Don't use images as main content of your post. This makes your question impossible to search and inaccessible to the visually impaired. Please transcribe text and maths (note that you can use LaTeX) and don't forget to give proper attribution to your sources!
Oct
6
comment Does AES CTR mode store header information in encrypted files?
What research have you done? Counter mode is described in many places, including on Wikipedia, in a NIST standards document, and in textbooks. Have you checked those places to see what they say about this? I think you'll find a number of different ways of nonce management described there.
Oct
4
comment Witness and Commitment in Commitment schemes
This site is not a book recommendation service, but Lindell & Katz is good for much intro level material, and Goldreich's book is worth reading too.
Oct
4
comment Witness and Commitment in Commitment schemes
What research have you done? Have you read standard textbooks on commitment schemes? This is a very basic level question, and should be settled by reading standard references. I expect you to do a significant amount of research/self-study on your own before asking; this site is not a replacement for that.
Oct
4
comment Cryptographic data structure: sparse array without membership test
1. Are you looking for a history-independent data structure? I suspect that's the term used in the literature for this concept. There is lots of work in the crypto literature on history-independent data structures for various purposes. 2. What does the attacker get to see? Does the attacker only get to see the state of the data structure after all get/set operations have completed? Or can he see its state at various points along the way?
Sep
28
comment Question about second preimage resistance of hash function combiner
possible duplicate of Guarding against cryptanalytic breakthroughs: combining multiple hash functions
Sep
28
comment Encrypted database: how to deal with general queries?
@mczraf, in fact, my understanding is that there has already been some industry adoption of CryptDB / the ideas in CryptDB. See e.g. css.csail.mit.edu/cryptdb/#Impact
Sep
28
comment Encrypted database: how to deal with general queries?
Please try to stick to one question per question. I see two questions: (a) how does the industry deal with encrypted databases? (b) is there anything that simulates somewhat homomorphic encryption? Question (a) is too broad. Question (b) is not well-defined (what do you mean by "at least simulate somewhat") so probably not suitable for this site in its current form. What research have you done? Have you looked at CryptDB (which has seen some deployment in industry)?
Sep
28
comment Question about second preimage resistance of hash function combiner
I can't understand the question. What does your notation $H^{s_1}(x)$ mean? Does it mean repeatedly applying $H$, $s_1$ times? If so, what does the notation $H^{s_1,s_2}(x)$ mean? What's $s_1$? I suggest editing the question to clarify.
Sep
22
comment Forward pseudorandom permutation
The question is unclear. What vectors? Where did those come from? What does it mean to have the same permutation at the server, in both vectors? I can't follow you. Try editing your question. Specify what is known to each party, what the inputs from each party are, and what the desired output to each party is. Also specify the trust model.
Sep
17
comment Are there cryptographic hash functions with homomorphic properties?
We already have questions here that provide lots of information on this subject. Simply searching on "homomorphic hash" in the search bar at the upper right turned up the following: crypto.stackexchange.com/q/6497/351, crypto.stackexchange.com/q/8074/351, crypto.stackexchange.com/q/12719/351. In the future, you might want to do a bit of research before asking, to help you ask a more informed question.