Will you support bit-oriented XTS in the next release?

The values seem non-sensical to me. Where did 137-bit data unit come
from? That's going to be a sector size in real life, so its going to
be 512, 2048, 4096, 64k, etc.
>>> In practice, there seems to be no such use case. 
在2021年5月20日星期四 UTC+8 下午7:37:31<Jeffrey Walton> 写道:

> On Thu, May 20, 2021 at 4:02 AM yu li <yu...@nvidia.com> wrote:
> >
> > Thank you for your reply.
> >
> > All test vector in 
> https://github.com/weidai11/cryptopp/blob/master/TestVectors/xts.txt. are 
> byte-aligned . I've tested these vectors locally, and they're all pass. But 
> it doesn't have a non-byte-aligned vector like datalen=250bit in 
> https://github.com/weidai11/cryptopp/blob/master/TestVectors/xts.txt. We 
> can found non-byte-aligned vector in 
> https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/CAVP-TESTING-BLOCK-CIPHER-MODES#XTS
>  
> . All byte-aligned vector in 
> https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/CAVP-TESTING-BLOCK-CIPHER-MODES#XTS
>  
> can pass, but all non-byte-aligned vector are fail.
>
> My bad Yu. I took alignment to mean type alignment. Sorry about that.
>
> XTS mode in Crypto++ is byte oriented, not bit oriented. We could
> possibly change that.
>
> I'm looking at 
> https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Algorithm-Validation-Program/documents/aes/XTSVS.pdf
> ,
> and it says (from p. 6):
>
> An implementation may support a data unit length that is not a
> multiple of 8 bits. In this case, the plaintext (PT) and ciphertext
> (CT) will be represented in the request, sample, and response files by
> a bit string padded with zeros on the right to the next byte boundary,
> in hexadecimal. For example, suppose an implementation supports a 137
> bit data unit. The first 128-bit block consists of the first (i.e.,
> leftmost) 128 bits. If the second, nine-bit partial block is
> 011011011, then in the request and sample files it will be padded with
> seven zeros on the right – 0110 1101 1000 0000 – and represented as
> 6d80 (hex). Response files values should be formatted the same way.
>
> The values seem non-sensical to me. Where did 137-bit data unit come
> from? That's going to be a sector size in real life, so its going to
> be 512, 2048, 4096, 64k, etc.
>
> Jeff
>

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