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I like crypto. Need I say more?


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
Apr
21
revised Usage of different size chunks during AES encryption/decryption
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Apr
21
revised Usage of different size chunks during AES encryption/decryption
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Apr
21
answered Usage of different size chunks during AES encryption/decryption
Apr
21
comment Usage of different size chunks during AES encryption/decryption
That's your problem then. I'll write up a detailed answer.
Apr
21
comment Usage of different size chunks during AES encryption/decryption
What IV do you use when you attempt to encrypt the next chunk?
Apr
21
comment Usage of different size chunks during AES encryption/decryption
What are you using as the IVs? For CBC the "IV" for the next block of data is the previous block of ciphertext. Therefore, if you generate a new IV for each chunk, but then just try to put chunks together to decrypt, you will have problems.
Apr
21
comment Usage of different size chunks during AES encryption/decryption
If I get some time, I'll write up an explanation of why it doesn't work. I'm curious. Why even split into chunks at all? Does a user ever need to access less than the whole file?
Apr
21
comment Usage of different size chunks during AES encryption/decryption
In general, no, it will not work. What are you trying to gain by doing that? If you explain your requirements, there may be something else we can point you towards to help. In other words, instead of describing a solution to your problem, why not tell us your problem.
Apr
18
comment Decrypting a small Message using RSA with a Private Key
In step 9, why are you raising to the 3?
Apr
15
comment Has there ever been more then a theortetical difference between preimage resistance and second preimage resistance?
Clearly having the message content could help. It has helped in some theoretical attacks (see here). Not sure if it has ever helped in practical situations.