[Cryptography] RFC: block cipher randomization

[Kent Borg]

On 06/27/2016 05:03 AM, Vlad wrote:
> Please review my proposals for block cipher randomization.
> Any feedback would be very appreciated.
> https://github.com/gluk256/misc/blob/master/encryption/randomization.md

I like it is simple enough that even I can understand it. And even I can 
criticize it!

The argument that is can't hurt is nice. But I am not sure I buy it 
because it unpredictably changes the amount of data going through, it 
changes the number of blocks that need to be encrypted; that will ripple 
up to higher layers, possibly breaking things there. Might cause 
programmers to craft broken variants on otherwise good encryption modes.

What about doing a fixed expansion, sprinkle exactly N-bytes of random 
stuff in pseudorandom locations? That will still keep it from being a 
drop-in can't-hurt idea, but seems less dangerous.

-kb