dsa: reduce Box<[u8]> allocation in SignatureEncoding::to_vec

[dishmaker]

Rewritten as SignatureRef

[baloo]

That is essentially what dsa::Signature is (dsa::Signature is composed of NonZero<BoxedUint>)

[baloo]

wouldn't it be possible to get an iterator over the inner limbs? and get big endian from there? without allocating a new box.

[dishmaker]

der checks for leading zeros when encoding UIntRef, so it would be too tricky

[baloo]

well that's just up to the consumer of the said iterator to strip leading zeroes? I don't know.

[baloo]

yeah nevermind, you have to have a buffer for SignatureRef, that can't be an iterator of limbs.

[tarcieri]

The crypto-bigint crate has native support for der, although it's missing DecodeValue/EncodeValue impls for BoxedUint (and NonZero<BoxedUint>). They exist for Uint.

Perhaps support could be added there so there's not need for complex encoding logic in the dsa crate.