cipher: fix Key: option in the stream_cipher_bench macro (#2290)

The option was not used in downstream crates. I tried to use it in
RustCrypto/stream-ciphers#544, but it failed
because of the incorrect implementation. For now I worked around it by
using the `Init:` option, so we are in no rush to release the fix.

Author: newpavlov

cipher/CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 0.5.1 (UNRELEASED)
+### Fixed
+- `Key:` option in the `stream_cipher_bench` macro ([#2290])
+
+[#2290]: https://github.com/RustCrypto/traits/pull/2290
+
 ## 0.5.0 (2026-02-04)
 ### Added
 - Traits for tweakable block ciphers ([#1721])

cipher/src/dev/stream.rs

@@ -151,8 +151,7 @@ macro_rules! stream_cipher_bench {
             Init: {
                 use $crate::KeyInit;
                 let key = test::black_box(Default::default());
-                let iv = test::black_box(Default::default());
-                <$cipher>::new(&key, &iv)
+                <$cipher>::new(&key)
             };
             $($name $bs;)*
         );