Questions tagged [blocksize]

A block is a sequence of bytes or bits, having a fixed length (the block-size).

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Effect of block size on diffusion rate

I've always been under the belief that larger block sizes require more rounds to achieve full diffusion. Rijndael, SPECK, and SIMON, for example, have a round multiplier based on the block size. The ...
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XTS and 256-bit data blocks

I am developer of an application that uses XTS with ciphers which use 128-bit blocks (AES, Serpent and Twofish). I now want to use XTS with a cipher which uses 256-bit blocks (Shacal-2). AFAIK, I ...
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All-or-nothing transform that doesn't increase message size?

All of the AON transforms I've read about involve generating a key, which increases the message by a few bytes. Is there an AON transform that preserves the message size while still having avalanche ...
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Implement Twofish cipher with 16-bit blocksize?

I've seen implementation of Rijndael cipher with 16-bit blocksize. And I have also tried to implement 16-bit Rijndael cipher by myself with only a little sneak peeking at the example of the ...
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Are blockciphers with 64-bit blocks still relevant (in any scenario)?

Facts Blockciphers are used to build encryption algorithms and compression functions for hash algorithms. (Unkeyed) Permutations are also complementing blockciphers in encryption and hashing. Large ...
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Cracking an appliance's network protocol

I'm trying to crack my thermostat's network protocol. I've captured several rounds of network traffic and here is what I've got to work with. Communicating via HTTP POST The POST data is JSON ...
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Can I use a password hash to encrypt the private key of a bigger block size?

I have private keys that are close to 2kb big. Now I want to password encrypt them in the following manner. Generate the private key of an asymmetric encryption algorithm (public key can be derived ...
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By using a block cipher multiple times in a row is a 128-bit BC as secure as a 256-bit BC which uses his 128-key only as part of the message?

For given 128-bit numbers $S$ and $E$ we want to find a series of keys $k_i$ with $$ E = BC(BC(BC(.....BC(S, k_1),k_2) ..k_n)$$ We can either use a 128-Bit blocksize block cipher similar to AES (ECB ...
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What would be the consequences of using a IV smaller than the block size in CBC encryption?

Here I use a Threefish kernel module with CBC mode. But there is no hash function that can supply a IV with Threefish block size (1024-bits), so I use a 64-bit random IV inserted in the dm-crypt with ...
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What is the security of XTS block cipher mode of operation if the key is much larger than the block size?

I made two Linux kernel modules of Hasty Pudding Cipher with key size of 16896-bits (16384-bits key + 512-bits tweak also called "spice), one has 512-bits of block size, the other 128-bits. I ...
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Can we combine two AES (with block size 128) to to a block cipher with a block size 192 which is collision-resistant?

Encrypting values with AES we only need about $2^{64}$ trials until we finding an already used value (some collision). This can be done these days with easy. To make this harder can we combine two AES ...
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Finding a dataset to benchmark cryptographic algorithms

I’m planning to compare cryptographic algorithms in terms of encryption/decryption time, memory used etc. and for that I’m in need of a standard dataset consisting of plaintexts of different bit sizes ...
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PGP private key format

I have a PGP Private Key from Bob. ...
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