On Jan 18, 2008 12:58 AM, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: > Kevin Coffman <kwc@xxxxxxxxxxxxxx> wrote: > > > > I'm obviously no expert. I hadn't realized that CTS could be used > > with ECB as well. However, if I'm understanding > > http://en.wikipedia.org/wiki/Ciphertext_stealing correctly, then > > things are done differently for ecb vs. cbc, so a generic wrapper as > > you are describing would have to have knowledge of the underlying > > block mode? > > Yes they are different due to the presence of the IV for CBC, however, > you can still implement it as one wrapper. However, that is not what's > important here. The important thing is that you should implement CTS > on top of "cbc(aes)", as opposed to just "aes". That way you can use > hardware acceleration which wouldn't be available if you were using > AES. > > So I'm fine if you implement CTS such that it only works with CBC, but > please do it so that it runs on top of the existing CBC code. > > > My first attempt tried to create asymmetrical input and output SG > > lists because I was avoiding moving and copying data to make them > > symmetric. (What I mean by asymmetrical is that the input list may > > have had 3 entries of length 40, 16, and 24 bytes, and the output list > > consisted of 2 entries of 48 and 32 bytes. As you can see, this also > > resulted in SG list entires that were not always an even multiple of > > the block size.) > > That's OK. You can do whatever is easiest for NFS. > > > Is it > > 1) a requirement that the input and output lists be symmetrical (same > > number of entries and matching lengths for input and output entries) > > and > > No. > > > 2) that each entry in the list deals with an even multiple of the block size? > > No. > > Cheers, > OK. Thanks very much. I'll see what I can get working. K.C. - To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
