Questions tagged [stream-cipher]
A stream cipher is an encryption algorithm which encrypts arbitrary length plaintext, using a key. Some stream ciphers generate a keystream from only the key, which is then XOR-combined with the plain text, others feed back plaintext or ciphertext into the algorithm to create the keystream.
571 questions
1 vote
1 answer
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PRGs and non linear LFSRs
My understanding is that we can formally prove that PRGs can generate a polynomial length pseudorandom expansion of the seed. But don't the LFSRs with non linear feedback like Trivium claim to ...
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2 votes
0 answers
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Why dont we see NLFSRs getting used with a counter?
This should give a period guarantee, which from what i have hear is good with NLFSRs right? It should also have diffusion and if we find a way to mix the key into it we would have confusion too.
3 votes
2 answers
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Is it possible to invert ChaCha20 rounds to recover an internal state of a specific round?
Can an adversary invert some rounds of ChaCha20 (or ChaCha12) to obtain the internal state of a specific round? I mean, if an adversary can invert 12 rounds of ChaCha20 to obtain the internal state of ...
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1 vote
1 answer
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Security implications of re-encrypting keystream instead of incrementing counter in stream cipher
Below is an implementation of a stream cipher algorithm, but it does not increment the counter. Instead, it directly encrypts the current key stream as the next key stream to encrypt the plaintext. I'...
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3 votes
1 answer
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How does a receiver recognize and handle a block of ciphertext as being "unsynchronized" in a self-synchronizing stream cipher?
Doesn't self-synchronization imply that some sort of protocol is in use: begin block, end block, checksum, etc.; incurring additional overhead in the resulting ciphertext compared to a synchronous ...
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3 votes
1 answer
203 views
Which ciphers and hash functions are easiest to conceal in compiled binaries?
I'm interested in understanding which ciphers and hash functions are the easiest to conceal or hide within a compiled binary (executable file). I'm not primarily concerned with the strength of the ...
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1 vote
2 answers
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Does using stream/block ciphers as PRNGs require a key and a initialization vector?
I'm asking this because when I asked the Mistral language model to provide source code for a PRNG based on stream/block ciphers, it provided an option to use a key and a IV in the code.
user127205
1 vote
1 answer
200 views
What are the differences between standard PRNGs and the ones based on stream/block ciphers?
So I learned that stream and block ciphers (in counter mode) can be used as PRNGs as well. How they differ from PRNGs like Xorshift, Mersenne Twister, Park-Miller etc. ?
user127205