Symmetric cryptosystems assume two communicating entities share a pre-established secret key.
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1answer
98 views
How do I calculate the maximum plain text length allowable for a certain cipher text length?
I am encrypting and storing sensitive values in the database. I have a set max length in the database, but in order to provide useful user feedback, I'd like to know the max input I should allow for a ...
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1answer
364 views
AES GCM symmetric encryption of data at rest in c#, ciphertext much longer than plaintext
I've written encryption/decryption routines using AES GCM. Code can be found here.
I recently realized that the cipher text is longer than I believe it should be. It should add the tag and IV onto ...
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1answer
80 views
brute force attack on KDF vs KEY
if we believe 256bit keys are secure in AES against any brute force attack, is that possible we use a KDF (convert user's weak entered password in truecrypt into a fixed AES key) with too much round ...
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1answer
72 views
Question about use of IV in this cipher
Main cipher objective : Generate a keyed CSPRN stream, that does not expose useful information about the state of the CSPRNG, and xor this with the plaintext. To prevent an attacked who could somehow ...
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2answers
126 views
Does gpg's symmetric encryption keep information about the filename?
If I encrypt a file with gpg -c file.zip, and change the filename. Is there any way I can restore the filename as I used as a password. or the name encrypted to?
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1answer
162 views
Polynomial for secure communication
Can we use a polynomial $P(x)$ to securely communicate ?
For example Alice & Bob agree on a degree of a polynomial. The value $x$ & the coeficients are generated from a seed using a hash ...
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1answer
70 views
Random decomposition of symmetric key
Considering a symmetric cipher (i.e : AES in counter mode), is it possible for any given key to be randomly decomposed into other keys without knowing the message or the ciphertext, such as :
100 = ...
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0answers
55 views
Perfect secrecy Proof
A symmetric cryptosystem have perfect secrecy $\iff$ for all
distribution over the messages space, $M$, and for all $m0$, $m1$ (messages) and any ciphertext $c$,
$$P(c|m0) = P(c|m1).$$
I got ...
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69 views
Cryptograpy library for Python [closed]
I was searching for libraries/modules for encryption of data and found a few such as M2Crypto and GNUTLS but both of them don't support CMAC which is what I wanted to use for authentication. Anyone ...
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2answers
166 views
Cryptographic Symmetric Stream Cipher
Let me know a cryptographic symmetric stream cipher system with only two functions say S() and P() and it should satisfy the following conditions:
There will be two independent computers say M1 and ...
-4
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0answers
28 views
pseudo random sequence and permutation functions [closed]
Iam doing my Master thesis in enhancing of an encryption algorithm by using of a pseudo random sequence generators to create a 16*16 shared table and apply a permutation function on it. one of the ...
