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23h
comment Security of tokenization of plain text conversations - cryptanalysis
For example, imagine encrypting a sixteen-character english word with AES-ECB. Each character can be encoded in one byte, so this is one block of AES ciphertext. However, you can encode the ciphertext to be stored in only about nine characters of Chinese, which gives you extra space to store metadata and headers with the ciphertext for easy parsing/decryption.
23h
comment Security of tokenization of plain text conversations - cryptanalysis
Marketing gimmick is part of it, but having worked on a system like this I can say authoritatively that there is a real reason why Chinese is advantageous: SaaS websites usually count a Chinese character as a single 'character' for field length limitations, but the entire Chinese code page lets you encode about 14-15 bits of cipertext into one character of Chinese. Using Chinese allows you to make ciphertexts as short as possible relative to the way 'length' is measured by these websites.
1d
comment Is there an open source library for Functional Encryption?
iacr.org/archive/eurocrypt2008/49650145/49650145.pdf
1d
comment Is there an open source library for Functional Encryption?
By 'inner-product encryption' I mean an encryption which supports inner product computation on ciphertexts.
1d
comment Is there an open source library for Functional Encryption?
Can your linear function be represented as a matrix? If so, you might be able to get away with something simpler like inner-product encryption to multiply your matrix (i.e. evaluate your linear function) on a value (vector) in the message space.
2d
comment Searchable Encryption with Substring Search
I don't understand what exactly you want. The second paper you linked by Chase and Shen is pretty much the state of the art in this area, so you might want to just do that.
2d
comment Searchable Encryption with Substring Search
CryptDB doesn't do this, and its security is not well-understood. CryptDB is not the right tool for this problem.
Apr
24
comment How to solve this public-key cryptography system?
It would be helpful if you could retype the problem instead of just including a picture of it.
Apr
23
comment What is transaction capacity of a POS using 3DES DUKPT?
Maybe you should explain the acronyms here and give some context for your question? I can't make heads or tails of what you're asking.
Apr
19
comment Which are similar encryption techniques as honey encryption?
Ristenpart published a follow-up at this year's Eurocrypt; you can check the proceedings.
Apr
18
comment Differences between OWP and OWF and their IND-CPA security
Can't you use the G-L hardcore bit to get a much simpler PRG than the one from the HILL result?
Apr
13
comment Find collision in Ajtai's hash function using short vector
I concur. I wish all questions were this nicely-written.
Apr
7
comment Can you give me a summary of cryptographic hardness assumptions?
If you email Vercauteren he might be able to get the site back up...
Apr
7
comment Can you give me a summary of cryptographic hardness assumptions?
web.archive.org/web/20120121090326/http://www.ecrypt.eu.org/… ?
Apr
3
comment Non-iterative cryptographic hash functions
Also, would (e.g.) a sponge-based hash like Keccak qualify as non-iterative?
Apr
3
comment Non-iterative cryptographic hash functions
I'm not sure I see what 'non-iterative' means formally. Can you give a more precise definition?
Apr
3
comment Check if a number is Carmichael number efficiently
Eh... Arguably this is in scope, because checking for Carmichael numbers is important in key generation for schemes involving large primes, which is most of them.
Apr
2
comment Are there any crypography schemes which rely on Graph Isomorphism not being in P?
Interestingly, though, graph non-isomorphism is a standard example of an interactive zero-knowledge proof for a language not in NP. If GI collapses to P, I think GNI goes with it, so we'll need a new example in our crypto textbooks.
Apr
2
comment Are there any crypography schemes which rely on Graph Isomorphism not being in P?
Nope, not that I know of. GI is not a great problem from which to build primitives, because it's been known for several decades that many (most) classes of graphs have a poly-time algorithm for deciding isomorphism.
Mar
31
comment A confusion on the proof of Yao's theorem (Yao 82)
Why does it matter? We fix a specific $n$ in the problem statement, and it holds for all $n$, and in fact the distinguishers are usually considered to be non-uniform Turing machines anyway so we can change the description of the program to make absolute values unnecessary for any $n$.