Implement belt dwp

[makavity]

Implemented Belt-DWP, republic of Belarus AEAD algorithm.

[makavity]

Hey, @newpavlov!
Could you check it, please? :)

[baloo]

This could use a rebase.

[makavity]

Looks like benches is broken in master

[newpavlov]

Sorry for the late review!

[newpavlov]

Same here, just use BeltDwp with the default type parameter.

[makavity]

   Compiling belt-dwp v0.1.0 (/Users/makavity/dev/crypto/AEADs/belt-dwp)
error[E0283]: type annotations needed for `BeltDwp<_>`
   --> belt-dwp/tests/belt.rs:39:13
    |
39  |         let belt_dwp = BeltDwp::new_from_slice(&vec.k).unwrap();
    |             ^^^^^^^^   ------- type must be known at this point
    |
    = note: cannot satisfy `_: cipher::block::BlockCipherEncrypt`
    = help: the following types implement trait `cipher::block::BlockCipherEncrypt`:
              &Alg
              BeltBlock
              cipher::tweak::zero::ZeroTweak<C>
note: required by a bound in `BeltDwp`
   --> /Users/makavity/dev/crypto/AEADs/belt-dwp/src/lib.rs:106:8
    |
104 | pub struct BeltDwp<C = BeltBlock>
    |            ------- required by a bound in this struct
105 | where
106 |     C: BlockCipherEncrypt + BlockSizeUser<BlockSize = U16>,
    |        ^^^^^^^^^^^^^^^^^^ required by this bound in `BeltDwp`
help: consider giving `belt_dwp` an explicit type, where the type for type parameter `C` is specified
    |
39  |         let belt_dwp: BeltDwp<C> = BeltDwp::new_from_slice(&vec.k).unwrap();
    |                     ++++++++++++

For more information about this error, try `rustc --explain E0283`.
error: could not compile `belt-dwp` (test "belt") due to 1 previous error

Should I use

let dwp: BeltDwp = BeltDwp::new_from_slice(&vec.k).unwrap();

?

[newpavlov]

Huh... weird. I guess one way to work around this issue is to write this:

pub struct Dwp<C> {
    cipher: C,
}

pub type BeltDwp = Dwp<BeltBlock>;

Though I am interested in learning why the default type parameter does not work here as expected.

[makavity]

The same problem is also in belt-ctr crate. Should I commit same fix for that?

[newpavlov]

Yeah, it's probably worth to define a generic Ctr type and BeltCtr = Ctr<BeltBlock> type alias on top of it.

[makavity]

Okay, thank you.
Fixed generic default by type alias, as you suggest.

[newpavlov]

Thank you!