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Mar
28
comment What might be assumed about a PRF if the key has been chosen?
I'm confused by "what might be assumed about..." -- you can of course assume anything you want. Do you mean, assuming only that $f$ is a PRF, what can we say about security if the key parameter is not chosen randomly? If so, the answer is: there are no guarantees whatsoever. There are bad cases where the function $f$ is no good at all, if the key is predictable or has low entropy. In TLS, the spec calls the function a PRF, but actually the protocol implicitly requires stronger assumptions than just that it's a PRF; it also needs to have some hash-like properties as well.
Mar
28
answered Is substitution with random prefix codes secure?
Mar
28
revised Is substitution with random prefix codes secure?
added 54 characters in body
Mar
28
comment ECDSA signature verifiable 1-way transformations
@ChristopheBiocca, you can turn any interactive ZKPoK into a non-interactive ZKPoK using the Fiat-Shamir heuristic (basically, use a hash function to choose the challenge). That should give you what you want.
Mar
28
answered Near preimages, applicable to Bitcoin?
Mar
28
answered ECDSA signature verifiable 1-way transformations
Mar
28
answered Is it possible to encrypt data in such a way that it cannot be decrypted with the key used to encrypt it but can be decrypted with another key
Mar
28
comment Distinguishing Attack on CBC-MACs
@user11291, read fgrieu's earlier comment, and do some learning on your own about the birthday paradox.
Mar
28
comment secure integer comparison
@ahmed, alas, I don't know of a reference for this protocol, and unfortunately I don't know anything better -- sorry about that -- but if you want to explore further, it might be worth taking a look at the protocol I mention in the last paragraph.
Mar
23
asked Proof of storage scheme
Mar
23
answered How to invalidate decryption key in multi user model?
Mar
22
comment Is PKCS #1 v1.5 RSA encryption padding secure under these conditions?
Your statement "Alice cannot know if Bob accepted the message" does not seem to be well-justified (at least, it does not follow from the rest of your conditions).
Mar
22
revised Do any one-key-of-many cryptographic schemes exist?
added 83 characters in body
Mar
22
revised Do any one-key-of-many cryptographic schemes exist?
added 123 characters in body
Mar
21
comment Parallel-resistant proof-of-work scheme without hidden knowledge
Thanks, that helps! For randomized schemes, can't you always make them deterministic by seeding a deterministic PRNG with some seed and using its output everywhere that the algorithm makes a random choice? Now the problem/puzzle generated will be a deterministic function of the seed: the same seed always yields the same puzzle. Does that achieve what you're looking for or does it fall short in some way?
Mar
21
reviewed Needs Improvement If PGP and GPG both follow the OpenPGP standard, are they 100% compatible in all use cases?
Mar
21
reviewed Needs Improvement ASCII: weakness
Mar
21
reviewed Needs Improvement Is this approach to generating a “random” number from a sha512 hash effective?
Mar
21
comment Is this approach to generating a “random” number from a sha512 hash effective?
Good answer! I'd also like to refer the author to crypto.stackexchange.com/q/767/351.
Mar
21
reviewed Needs Improvement simple multiplication in GF(8)