I've been researching cryptographic modes and came across an obscure mode called interleaved CBC (ICBC). I can't find a lot about it and am wondering if anyone knows anything more.
It's basically CBC but where instead of chaining the last block you chain the n-mth block where m is some constant. This allows some amount of parallelization. For example if m is 8 you can do 8 blocks at a time. For message indistinguishability you'd also need an IV as wide as the block cipher times m, which could probably be expanded from a shorter IV.
Anyone know what this is? I suppose it would be considered obsolete but it would perhaps have some desirable properties in certain applications.
Edit: as near as I can tell this would be identical security-wise to splitting the message into
m smaller messages and encrypting each with CBC. The fact that the message is split by being "striped" rather than split into chunks seems irrelevant. Does this basically just reduce to CBC (assuming the IV is unique per stripe)?
Also this would have to be authenticated of course to prevent padding oracle attacks.