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Follows suit with `serde` support in other RustCrypto crates by using `serdect` to implement `Serialize` and `Deserialize`, replacing the previous use of `serde_bytes`. These serializers use the `serdect::array` serializers which use efficient format-specific byte encodings (albeit with a length prefix) when serializing to binary formats, or a hex encoding with human readable formats like JSON and TOML.
This was referenced May 3, 2026
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* [WIP] ed25519-dalek: bump `ed25519` crate dependency to v3.0.0
This has two test failures:
serialisation::serialize_deserialize_signature_json
serialisation::serialize_signature_size
These are due to a last minute change to use `serdect` for implementing
`serde` support: RustCrypto/signatures#1324.
The signature size regression from `64` to `72` is a deliberate tradeoff
we've accepted in `serdect`. First note that this test is for now the
unmaintained `bincode` crate.
The core problem is that `serde` does not actually provide fixed-size
arrays as a type within its data model (serde-rs/serde#1937) and you're
instead left faking it using `SerializeTuple` and serializing it a
byte-at-a-time as a tuple. While this gives optimal-sized results on
`bincode`, it gives less-than-optimal results on e.g. `rmp-serde` where
the bytes each end up tagged with a type prefix.
`serde` does provide portable APIs for using optimal format-specific
byte encodings, but they carry an additional length prefix, which is
unnecessary and suboptimal for something fixed-width like an Ed25519
signature, but alas as noted earlier `serde` does not actually have
fixed-width arrays in its data model.
The second test failure occurs specifically because `serdect`
introspects the format and uses `base16ct` to perform hex serialization
for human readable formats. While this is a readability improvement for
these formats (and also makes them easier to implement in constant-time,
though it's not relevant here), the drawback is it currently requires
the `alloc` feature for such formats, which is a regression:
Error("serializer is human readable, which requires the `alloc` crate feature", line: 0, column: 0)
Note that regardless these are both breaking changes to how `serde`
serialization is handled.
See also:
- RustCrypto/formats#1111
- RustCrypto/formats#1112
- dalek-cryptography/ed25519-dalek#140
* Migrate bincode -> postcard
* Bump `serdect` to v0.4.3
Includes `no_alloc` hex serialization support
---------
Co-authored-by: Michael Rosenberg <mrosenberg@cloudflare.com>
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Follows suit with
serdesupport in other RustCrypto crates by usingserdectto implementSerializeandDeserialize, replacing the previous use ofserde_bytes.These serializers use the
serdect::arrayserializers which use efficient format-specific byte encodings (albeit with a length prefix) when serializing to binary formats, or a hex encoding with human readable formats like JSON and TOML.