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Working in industry as a cryptography engineer.

To contact me, email paulgrub AT umail DOT iu DOT edu


Sep
3
comment Statistical tests for pseudorandom permutations
Also, my internal PRP in the FPE scheme is merely an unbalanced Feistel network similar to the Thorp shuffle.
Sep
3
comment Statistical tests for pseudorandom permutations
Yeah, I don't plan on relying solely on statistical tests to argue the security of my scheme. I think of passing statistical tests as a necessary but not sufficient condition for security.
Sep
3
comment Statistical tests for pseudorandom permutations
Saw that one. Thanks much :)
Sep
3
asked Statistical tests for pseudorandom permutations
Aug
29
comment How does Random Oracle and Standard Model differ?
Well, yes and no. The counterargument is that good crypto is about minimizing the assumptions you have to make. Assumptions are dangerous.
Aug
26
reviewed Approve suggested edit on How is SHA1 different from MD5?
Aug
13
comment How is SHA1 different from MD5?
I don't understand your question - every hash function can be described as having "chunks of bits, bit rotation, xor, and special functions".
Aug
10
comment Is HMAC-SHA-1 secure?
The gist is that the HMAC construction has properties which allow its security definition to be met even if the hash used internally is not a cryptographic hash. It need only meet a weaker definition, which is why HMAC-MD5 is also still considered secure.
Aug
8
comment Hardware Implementation of Pairing over BN curves
Whoa... that sounds really interesting. I only know epsilon about pairings, but do you have like a project page or a description of what you're trying to accomplish?
Aug
6
comment Homogenous and heterogeneous Unbalanced Feistel Networks
One person who could give a really good answer to this is Thomas Pornin... You could email him if you don't have a satisfactory answer in a few days.
Aug
6
comment How feasible is word-level frequency analysis over English (or any language)?
You can call it a codebook if you want, but it has nothing to do with ECB.
Aug
6
comment How feasible is word-level frequency analysis over English (or any language)?
Another thing that's been bugging me: Don't all these methods only work for guessing fairly common words from the corpus? If the word distribution is like most languages, there is a small subset of very common words at the top of an inverse-power-law curve, then most words are nearer to the bottom. For example, statistical attacks can easily guess which token corresponds to 'the' but 'finance' or 'contract' would be much harder to guess.
Aug
6
comment How feasible is word-level frequency analysis over English (or any language)?
Ahh I hadn't thought of using close-word statistics. Though doesn't that assume at least partially known plaintext?
Aug
6
comment How feasible is word-level frequency analysis over English (or any language)?
No it isn't. ECB is a block cipher mode of operation.
Aug
6
comment Straightforward method for hampering frequency analysis on deterministic encryption
Also - can the downvoter explain? I think this is a reasonably well-articulated question that is not too open-ended.
Aug
6
comment How feasible is word-level frequency analysis over English (or any language)?
Interesting, thanks for your answer. What if after tokenizing each document, the words in the document were shuffled according to some pseudorandom permutation like the Knuth shuffle? Something that is reversible with a secondary secret key that the adversary doesn't know.
Aug
6
comment How feasible is word-level frequency analysis over English (or any language)?
Don't assume anything about the black box. Also, what is an 'ECB substitution cipher'?
Aug
6
comment How feasible is word-level frequency analysis over English (or any language)?
I looked at the other question, they are not even close to being duplicates. The other one is talking about a classical substitution cipher and is unrelated to modern cryptography.
Aug
6
comment Straightforward method for hampering frequency analysis on deterministic encryption
Apologies for forgetting to link the two together, but I do not think an answer to the other question constitutes an answer to this one.
Aug
6
comment How many degrees of freedom up my sleeve?
Also check out this new project on manipulating SHA1 constants to create weak hash functions: malicioussha1.github.io