Crypto algorithm identification (reverse engineering)
Is there a 2048-bit variant that is commonly used, or some kind of optimization that allows the next round for each block to be computed in parallel while still using an initialization vector?


Bit slicing is an optimization technique that consists in calculating $b$ instances of a function (e.g. $n$ block decryptions/encryptions) in parallel on a machine with $b$ bits. An apparent 2048-bit block size is consistent with a 64-bit cipher and a 32-bit bitslice. Bitslicing can only be done when the data for block operation $n+1$ doesn't depend on the output of block operation $n$, so it's useless for e.g. CBC mode but can be used for e.g. CTR mode.