The `signature` crate provides `Signer` and `Verifier` traits generic
over signature types:
https://github.com/RustCrypto/traits/tree/master/signature
There's presently an open call to stabilize the parts of its API needed
by Ed25519 signatures and release a 1.0 version:
https://github.com/RustCrypto/traits/issues/78
The `ed25519` crate, based on the `signature` crate, provides an
`ed25519::Signature` type which can be shared across multiple Ed25519
crates (e.g. it is also used by the `yubihsm` crate):
https://github.com/RustCrypto/signatures/tree/master/ed25519
This commit integrates the `ed25519::Signature` type, and changes the
existing `sign` and `verify` methods (where applicable) to use the
`Signer` and `Verifier` traits from the `signature` crate. Additionally,
it replaces `SignatureError` with the `signature` crate's error type.
This has the drawback of requiring the `Signer` and/or `Verifier` traits
are in scope in order to create and/or verify signatures, but with the
benefit of supporting interoperability with other Ed25519 crates which
also make use of these traits.
* ADD new "batch" feature for feature-gating ed25519 batch verification; off by
default. The "batch" feature is the only thing which depends on all of the
`rand` crate, since it requires the functionality of `rand::thread_rng()`.
Without batch verification, the rest of ed25519-dalek only depends on
`rand_os` and `rand_core`.
This implements https://github.com/dalek-cryptography/ed25519-dalek/issues/64
You can still choose the "prehash" algorithm, as long as it has 64 bytes of
output. Otherwise, everything is hardcoded to use sha2::Sha512. To use a
different implementation you'll need a [patch.crates-io] section in cargo
config.
This caches the public key internally so that we effectively get a free
speedup on key reuse in regular signature verification, similar to that in
batch verification. (However, this also "speeds up"¹ batch verifications.)
¹ Less of a speed up than moving the computation elsewhere, but the speed up
on reuse still also applies to key reuse for batch verification.
Unfortunately the serialised size is likely never going to be the same
as the type's size in memory, as most serialisation formats define
additional headers for parsing safety reasons, such as buffer lengths
and type information.
generic_array v0.12 no longer serializes GenericArray as a Vec,
which reduces the serialized size of PublicKey, Signature, and
SecretKey by 8 bytes. Now that generic_array has been upgraded,
these tests simply ensure the serialization size doesn't change
in the future.
