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Nov
24
comment Is this new server API authentication protocol secure?
How do you intend to generalize HMAC-256 to take 3 arguments? $\:$ What will the operation "+" represent? $\;\;\;\;\;$
Nov
24
comment What is the difference between a bijective random oracle and a random permutation?
Note that even if they are both available to everyone, "random permutation" would suggest a stricter limit on the number of queries than "random bijective oracle" would. $\:$ (See FPE.) $\;\;\;$
Nov
24
comment Why does plain RSA not work with big messages ($m>n$)?
Yes. $\:$ We encrypt a key. $\;\;\;$
Nov
24
revised Bit commitment with 1-out-of-2 oblivious transfer
fixed spelling
Nov
24
revised Asymptotic Hash Function and Concrete Hash Function
improved grammar and tags
Nov
23
comment Why is this MAC based on secure PRF with ordering and randomization insecure?
Could they be just referring to the fact that for every way of padding messages whose length is not $\hspace{.44 in}$ a multiple of $n$ to strings whose length is a multiple of $n$, the resulting algorithm will be insecure? $\hspace{.6 in}$
Nov
23
comment Finding ECDSA public key from signature samples
Would it be a public key from a given list, or just a completely unknown public key? $\hspace{1.62 in}$ If it's from a list, would the keys in the list use the same curve parameters and/or hash? $\hspace{1.42 in}$ Would the messages that were signed be known? $\;$
Nov
23
comment What is the impact of the Goppa code distinguisher on the CFS and McEliece?
I would guess that McEliece PKE does not use high-rate Goppa codes. $\;$
Nov
23
comment Creating a secure key
The slightly less straight but still provably secure-if-CDH-is-hard idea is to run the protocol $\:\Theta(k/(\log(k)))\:$ times and obtain logarithmically many hard-core bits, as described on page 32 of this paper. $\hspace{1.06 in}$
Nov
22
comment Creating a secure key
@nightcracker : $\:$ Could your suggestion be shown to be secure in the plain model? $\hspace{1.4 in}$
Nov
22
comment Merkle Signature Generation
@juaninf : $\;\;\;$ In Merkle signatures, after signature key $X_s$ is used, $X_s$ is discarded so that someone else reading the location in memory that held $X_s$ would not result in a security failure, although $X_s$ could be regenerated from the overall signing key $X$. $\;\;\;\;\;\;$
Nov
22
comment Is there a companion algorithm for OTP to ensure integrity and/or authentication?
It is wasteful because it uses part of the key for encrypting the MAC tag. $\:$ Using UMAC for this would require either an unconditionally secure stateless encryption algorithm (which, as far as I know, would need a lot more key material) or would require that the verifier know the message number even if the MAC was just used for authentication of non-encrypted messages. $\;\;\;$
Nov
22
answered How to break AES/CBC/PKCS5 when key and IV are reused?
Nov
21
comment What scheme will allow merging and splitting the result of a function?
Does this need to be able to handle arbitrary functions? $\;$
Nov
21
reviewed Reject suggested edit on pir tag wiki
Nov
21
reviewed Approve suggested edit on pir tag wiki excerpt
Nov
21
comment How does the length of the plaintext affect the cipher strength?
I try to line-up the lines and space-out the sentences. $\;$ (For some reason, it occasionally changes how they render a few minutes after I post them.) $\;\;\;$
Nov
21
comment How does the length of the plaintext affect the cipher strength?
You seem to be missing my point. $\:$ Your second sentence should have something corresponding to $\hspace{.56 in}$ the last part of "if x, which is likely, then y", although it doesn't actually need to use the word "then". $\hspace{.42 in}$ "What is the strength of the block cipher, if any unknown attacks, which could reduce its strength", $\:$ ... . $\hspace{.38 in}$
Nov
21
reviewed Approve suggested edit on hill cipher encryption way 1x3 plaintext matrix
Nov
21
comment Is the following symmetric design secure?
R is generated in the same way that randomized padding for PKE is generated, so the attacker does not know R. $\:$ R is transmitted in the ciphertext, and is large enough that the number of oracle queries by the adversary must be much less than 2^(length(R)). $\:$ M is one bit longer than the maximum possible plaintext length, and K is length(M)+length(R) bits long. $\;\;\;$