RustCrypto · kkohbrok · Apr 29, 2026 · Apr 29, 2026 · Apr 29, 2026
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/tls_codec/CHANGELOG.md b/tls_codec/CHANGELOG.md
@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- [#2022](https://github.com/RustCrypto/formats/pull/2022) Optimize serde serialization of byte vectors using `serde_bytes`. Deserialization of the old serialized format will still work, but newly serialized instances of `VLBytes` will have the new format.
+- [#2322](https://github.com/RustCrypto/formats/pull/2322): Add `VLByteVec` and `SecretVLByteVec`, which are `#[serde(transparent)]` wrappers serializing via `serde_bytes`. They produce a much more compact representation in `serde` formats that distinguish byte arrays from sequences of `u8` (e.g. CBOR, MessagePack, bincode). Their `serde` output is not compatible with `VLBytes` / `SecretVLBytes`, but their `Deserialize` impls are backwards-compatible: in self-describing `serde` formats they also accept the legacy `VLBytes` / `SecretVLBytes` encoding (a struct with a `vec` field containing a sequence of `u8`). Deprecate `VLBytes` and `SecretVLBytes` in favour of `VLByteVec` and `SecretVLByteVec`.
 - [#1656](https://github.com/RustCrypto/formats/pull/1656) Add `TlsVarInt` type for variable-length integers.
 
 ## 0.4.2

diff --git a/tls_codec/Cargo.toml b/tls_codec/Cargo.toml
@@ -23,6 +23,7 @@ serde_bytes = { version = "0.11.17", optional = true }
 [dev-dependencies]
 criterion = { version = "0.6", default-features = false }
 ciborium = "0.2.2"
+serde_json = "1.0"
 
 [features]
 default = ["std"]

diff --git a/tls_codec/benches/quic_vec.rs b/tls_codec/benches/quic_vec.rs
@@ -1,3 +1,6 @@
+// The benches intentionally exercise the deprecated `VLBytes`.
+#![allow(deprecated)]
+
 use criterion::{BatchSize, Criterion};
 use criterion::{criterion_group, criterion_main};
 

diff --git a/tls_codec/derive/tests/decode.rs b/tls_codec/derive/tests/decode.rs
@@ -1,4 +1,7 @@
 #![cfg(feature = "std")]
+// These tests intentionally exercise the deprecated `VLBytes` for backward
+// compatibility coverage.
+#![allow(deprecated)]
 use tls_codec::{
     Deserialize, DeserializeBytes, Error, Serialize, Size, TlsSliceU16, TlsVecU8, TlsVecU16,
     TlsVecU32, VLBytes,

diff --git a/tls_codec/fuzz/fuzz_targets/inverse.rs b/tls_codec/fuzz/fuzz_targets/inverse.rs
@@ -1,4 +1,5 @@
 #![no_main]
+#![allow(deprecated)]
 
 use libfuzzer_sys::fuzz_target;
 use tls_codec::{Deserialize, Serialize, Size, VLBytes};

diff --git a/tls_codec/src/lib.rs b/tls_codec/src/lib.rs
@@ -49,8 +49,13 @@ pub use tls_vec::{
 };
 
 #[cfg(feature = "std")]
-pub use quic_vec::{SecretVLBytes, rw as vlen};
-pub use quic_vec::{VLByteSlice, VLBytes};
+#[allow(deprecated)]
+pub use quic_vec::SecretVLBytes;
+#[allow(deprecated)]
+pub use quic_vec::VLBytes;
+#[cfg(feature = "std")]
+pub use quic_vec::{SecretVLByteVec, rw as vlen};
+pub use quic_vec::{VLByteSlice, VLByteVec};
 
 #[cfg(feature = "derive")]
 pub use tls_codec_derive::{