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  • 44 votes cast
Apr
12
comment CTR_DRBG versus OFB_DRBG
It is because OFB has short cycles and can't be computed in parallel.
Apr
10
comment Discover key with known-plaintext attack
You can't simply find out the encryption method without knowing key.
Mar
27
comment Is the SEED blockcipher still secure?
@VincentAdvocaat You can encrypt same block multiple times (10000x). If you need fast stream cipher I would suggest ChaCha.
Mar
24
comment Is the SEED blockcipher still secure?
I'm also wondering, why your SEED is much faster when decrypting?
Mar
24
comment Is the SEED blockcipher still secure?
In my experiences SEED is noticeably slower than AES on x86_64.
Mar
20
comment What is the most light-weight symmetric cipher thats still usefull?
@Muis I think ChaCha is the best choice for this CPU. DES, LED, PRESENT, and Piccolo are fast in hardware, but slow in software. RC4 is good for 8-bit CPUs.
Mar
18
comment What is the most light-weight symmetric cipher thats still usefull?
So your platform is ARM Cortex-M0 LPC11A14 at 48 MHz or similar?
Feb
25
comment Why can the last block contain a full block of padding in CBC Encryption?
How will you know that there is no padding? It must always be padded otherwise it is not reversible.
Dec
26
awarded  Critic
Dec
23
comment How were shift amount constants in MD5 found?
They were probably found by empirical testing. XORs and additions are replaced with ORs then you set block to all null but one, full diffusion happens when block is all ones. Look at schneier.com/skein1.3.pdf "Appendix D NIST SHA-3 Round 2 Tweak: Rotation Constants" and "D.1 Deprecated Skein Rotation Constants".
Dec
17
comment Dancing confusion with Daniel J. Bernstein's stream ciphers
XChaCha implementation (XSalsa20's nonce and ChaCha's diffusion): github.com/lightbit/kripto/blob/master/lib/stream/chacha.c
Nov
29
revised block cipher algorithms with variable block lengths
added 1 character in body
Nov
29
answered block cipher algorithms with variable block lengths
Nov
19
comment Do data-dependent rotations have any advantage over fixed rotations?
Ignoring patents, implementation problems, hardware do disadvantages still outweigh advantages?
Nov
19
accepted Do data-dependent rotations have any advantage over fixed rotations?
Nov
18
asked Do data-dependent rotations have any advantage over fixed rotations?
Nov
16
comment Block cipher to encrypt 8 bytes/64 bits - Use 64 or 128 bit cipher?
If you want compact 64-bit block cipher, I would suggest Speck or RC5. XTEA should also be fine, but you have to be careful with key management (as always).
Nov
14
comment Why we can't implement AES 512 key size?
AES-like block cipher used in Whirlpool hash has 512-bit block size and key size.
Nov
11
awarded  Yearling
Nov
11
comment Extending key sizes in Salsa20 and ChaCha?
@John It depends how long stream would be. If key1 = 12 and key2 = 19, you will get same blocks, but with different offset. Result is similar to nonce reuse, which is serious defect. Counter must always be initialized to the same fixed value.