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I like crypto. Need I say more?


Apr
23
comment Spurious keys filter
@ceasif good luck with your research. I hope you find this site useful in your research.
Apr
23
answered Spurious keys filter
Apr
23
comment Which homomorphic encryption scheme has the same size of plaintext space and ciphertext space?
@JianLiu so even in the SV scheme, the plaintext space and the ciphertext space have very different sizes.
Apr
23
comment Which homomorphic encryption scheme has the same size of plaintext space and ciphertext space?
@JianLiu, you are right. I am not super familiar with the SV system. Ciphertexts are an integer modulo p. Plaintexts are either a single bit or (if you follow section 6) a binary polynomial of degree $N-1$. So to know how the plaintext and ciphertext spaces compare you need to know how $p$ and $N$ compare. To get an idea of how these compare, look at the table in Section 7. They have (for one instance) $N=2^8$ (since $n=8$ and $N=2^n$) while $p\approx 2^{4096}$ (a 4096 bit prime).
Apr
23
answered Cryptography systems based on NP complete problems
Apr
23
revised Cryptography systems based on NP complete problems
edited body
Apr
23
reviewed Edit suggested edit on key-generation tag wiki
Apr
23
revised key-generation wiki description
deleted 6 characters in body
Apr
23
reviewed Approve suggested edit on key-generation tag wiki excerpt
Apr
23
answered Which homomorphic encryption scheme has the same size of plaintext space and ciphertext space?
Apr
23
comment Which homomorphic encryption scheme has the same size of plaintext space and ciphertext space?
The size of the ciphertext space is often a function of the security parameter. If you shrink the ciphertext space too small, the cryptosystem becomes insecure.
Apr
23
comment Which homomorphic encryption scheme has the same size of plaintext space and ciphertext space?
That one still does not have equal size plaintext/ciphertext spaces (I'm assuming you're referring to section 6). The plaintext space is binary polynomials of degree less than N. The ciphertext space is non-binary polynomials of degree less than N. If you think about it, you could not have a semantically secure public-key cipher where the plaintext and ciphertext spaces are the same size. Non-semantically secure public-key homomorphic ciphers are of little interest.
Apr
23
comment ECC Complexity order of point addition, scalar point multiplication and selecting random point
Are you wondering about order of operations in elliptic curves?
Apr
23
comment Spurious keys filter
Perhaps you are looking for something like this technologyreview.com/news/523746/…
Apr
23
comment Which homomorphic encryption scheme has the same size of plaintext space and ciphertext space?
I doubt that any exist. Else, how could we have semantic security? Also, the ciphertext space for modern public-key ciphers is so large you could never pre-compute results for all possible ciphertexts. Perhaps it would be better if you described the problem you are trying to solve and let us help you figure out a solution. Right now you are describing a possible solution to some unknown (to us) problem.
Apr
22
comment Burn after read algorythm. Software verification on compromised environment. Software smart card
You might find this paper interesting.
Apr
21
comment Usage of different size chunks during AES encryption/decryption
Glad we figured it out. In your learning, please feel free to continue using this site to help you. I'd suggest you read the help center on the types of questions that are on topic here.
Apr
21
comment Is it possible to track down copies of WW2-era codebooks?
Perhaps the NSA has some? nsa.gov/about/cryptologic_heritage/museum
Apr
21
answered Leaving authentication data blank less secure for AES GCM?
Apr
21
revised Usage of different size chunks during AES encryption/decryption
edited tags