On Thu, Nov 24, 2016 at 04:57:51PM +0100, David Gstir wrote: > > > Also, if the intent is just that the 'index' represent the data's offset in > > filesystem blocks rather than in pages, then perhaps it should be > > documented as > > such. (This would be correct for ext4 and f2fs; they just happen to only > > support encryption with block_size = PAGE_SIZE currently.) > > Yes, in case of UBIFS it is exactly that. > > However, I'm actually not really happy with the name 'index'. I'd rather call > it 'iv' (or 'tweak') directly. In the context of encryption its purpose will > be more obvious, especially in regard to the "IV _must_ not be reused" > constraint you mentioned above. >
Well, the way I'd prefer to think about it is that the filesystem does not provide an IV directly (it doesn't anyway, since the actual IV is a u8[16]), but rather the number of the logical block of the file, like 'u64 lblk_num'. And that is sufficient to avoid IV reuse. Eric
