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Sep
5
revised Can Bitcoin HD public keys be used for symmetric encryption?
added 497 characters in body
Sep
5
answered Can Bitcoin HD public keys be used for symmetric encryption?
Sep
4
awarded  Yearling
Sep
4
comment Is using SHA256 to extract entropy from a p-rand nonce a good way to create keying material?
+1 Always best to stick with standards.
Sep
4
comment Is using SHA256 to extract entropy from a p-rand nonce a good way to create keying material?
Personally, I'd use HMAC-SHA256. See this paper for why and some other possible constructions to consider (especially if your processor has AES-NI).
Sep
4
comment Can Bitcoin HD public keys be used for symmetric encryption?
Let me see if I understand. You have two parties who have previously shared (part) of a wallet. You want to use that shared information to establish secure communications between the two. Is that correct?
Sep
2
comment How to make a document truly read only
And remember, this is a cryptography site so our solutions will definitely be geared towards cryptography. There could be non-cryptographic answers to the question.
Sep
2
comment How to make a document truly read only
Answer is, you probably can't. Anyways, you need to define a threat model. What do you consider a breach of "read only"? If someone memorizes the document and types it out in a new word processor document? Printing? Etc. If you can formally define what it means to be read-only, we may be able to help.
Sep
2
comment How Proof all Subgroup point of prime order elliptic curve have prime order [#G=#E]?
Given Lagrange's theorem (which will be in any decent textbook on number theory), the proof is straight forward.
Sep
2
revised How Proof all Subgroup point of prime order elliptic curve have prime order [#G=#E]?
added 1 character in body
Sep
2
comment How Proof all Subgroup point of prime order elliptic curve have prime order [#G=#E]?
Actually, there is one point for which this will not hold.
Aug
27
comment What's the point of a Meet In The Middle attack using i.e. double AES with throw-away keys?
First off, a meet in the middle attack on AES is not even computationally feasible, so an attacker wouldn't use it period.
Aug
26
awarded  Pundit
Aug
26
comment How to distribute symmetric key between $n$ entities?
Shamir secret sharing?
Aug
22
comment Is it secure to derive an AES key from a MAC?
@HannoBinder your idea is valid, but I don't necessarily think it is simpler.
Aug
22
comment Is it secure to derive an AES key from a MAC?
@Augusto are you the OP? They seem reasonable to me. In any usable system there is going to be a point where security breaks.
Aug
22
answered Is it secure to derive an AES key from a MAC?
Aug
22
comment Is it secure to derive an AES key from a MAC?
Having never worked with HSM's, is there any sort of authorization with them? I.e., to prove that you are allowed to generate keys? An attacker stealing the database who also has access to the server with the HSM, could issue the random numbers to the HSM and get back the decryption keys.
Aug
22
comment How does a chosen plaintext attack on RSA work?
Link only answers are not typically well received here. While the paper is a very good one, you should consider expanding by talking about what information the paper presents that is specifically related to the question.
Aug
19
awarded  Good Answer