All Questions
Tagged with symmetric modes-of-operation
16
questions
0
votes
2
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125
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Multiple IV CBC
CBC's encryption is not paralelizable but I could divide a 64 block message in 4 16 block parts and encrypt those 4 parts separatly in parallel using a diferent IV for each one. Is this unsecure ? Is ...
- 363
0
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0
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234
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Another cut-and-paste attack on CBC mode
I am trying to see specific cases of attacks in the CBC mode, in particular, I am investigating some attacks such as Example of a cut-and-paste attack on CBC. Here I have posted something similar and ...
- 131
0
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151
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AES encryption question
If we consider the generation of keys as
$$\begin{aligned}
K_0 &= E_K(IV); \\
K_{i+1} &= E_{K_i}(A)
\end{aligned}$$
Where A is a block of zeroes, and the ciphertext blocks are computed as
...
- 1
0
votes
1
answer
326
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Is this method of speeding up a symmetrical algorithm secure? (AES output joining)
I was trying to find out a way of speeding up a given symmetrical algorithm the reason and programing launguage in this case are unimportant. I have came up with the following thing:
Divide data into ...
- 3
3
votes
1
answer
256
views
Why does the Gameboy Advance serial encryption include the destination byte address?
The Gameboy Advance encrypts data sent over its serial port. It assembles a random number to seed a linear congruential generator. Then, it xors this PRN, the data, a symmetric key, and the byte ...
- 33
2
votes
3
answers
295
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Are there any deterministic multi-block encryption constructions that have an avalanche effect going both ways?
For common multi-block encryption schemes (CBC, CTR, CFB, stream ciphers, etc), if they are forced to be deterministic, a change in the plaintext will change only the current block and maybe future ...
- 2,419
8
votes
1
answer
173
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Is the risk of a collision for OCB mode mitigated by upping the block size of the cipher?
A paper published by Niels Furguson Collision attacks on OCB indicates that processing large amounts of data (somewhere on the order of $2^{32}$ 128-bit blocks) with a single encryption operation (...
- 143
1
vote
1
answer
658
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Is this symmetric key MAC-then-encrypt auth token methodology secure?
NOTE: This question originally conflated a "digital signature" and a "MAC", which I've since learned are not the same thing. Any references (in the answer or any comments) to a "signature" should be ...
- 121
1
vote
2
answers
775
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How effective is Serpent-256 in CTR mode?
I downloaded a compression program known as PeaZip which offers encryption and 2-way authentication also.
PeaZip has an option to encrypt compressed file with variety of ciphers and one of them is ...
- 571
5
votes
2
answers
885
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How secure would hand ciphers be using a Block Cipher Mode?
I've been looking into different ciphers that require very minimal computation power (calculator, deck of cards, index cards and a pencil), i.e. hand ciphers. For the most part all methods typically ...
- 161
5
votes
2
answers
3k
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Secure method for encrypting 32 byte private keys
I am using 32 byte EC private keys on the client side of a web application. These keys should be securely stored on a server database. The keys should be encrypted (AES) before being sent to the ...
- 153
2
votes
2
answers
3k
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IV/Nonce in CTR&GCM mode of operation
We know reusing IV can compromise our secrecy. I have some questions aiming to clarify the use of an IV/Nonce in CTR/GCM:
Is it OK to use the same key for encrypting plain-texts in authenticated ...
- 29
12
votes
4
answers
4k
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What is the difference between a 'cipher' and a 'mode of operation'?
What is the difference between the term cipher (a name like RIJNDAEL) and mode of operation (like ECB)?
Aren't these both terms for the encryption/decryption technique?
- 229
3
votes
1
answer
334
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Camellia cipher - is it a symmetric or asymmetric cipher?
I read a wiki page about Camellia cipher and know that it is a block cipher that can use 128-bit, 192-bit or 256-bit keys. But I cant find any information about if its a symmetric cipher (uses one key ...
- 141
4
votes
0
answers
1k
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Symmetric encryption mode where ciphertext size is plain text size [duplicate]
I've had many questions on Stackoverflow on how to minimize the output of a cipher - during encryption of course - to the same size as the input. Obviously this is possible for a single block of ...
- 93.4k