From 7c693fb23c4100ecd975274131e05c704516cff1 Mon Sep 17 00:00:00 2001
From: Tony Arcieri <bascule@gmail.com>
Date: Sun, 25 Oct 2026 14:51:23 -0600
Subject: [PATCH] sntrup-kem: replace `subtle` with `ctutils`

`subtle` is unmaintained and `ctutils` is the standard library we use
for constant time for all of the other KEM implementations in this repo
---
 Cargo.lock              |  2 +-
 sntrup-kem/Cargo.toml   |  2 +-
 sntrup-kem/src/types.rs | 14 +++++++-------
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index f2859e6..9c7d697 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1341,6 +1341,7 @@ name = "sntrup-kem"
 version = "0.1.0"
 dependencies = [
  "criterion",
+ "ctutils",
  "getrandom",
  "hex",
  "hybrid-array",
@@ -1352,7 +1353,6 @@ dependencies = [
  "serde_json",
  "serdect",
  "sha2",
- "subtle",
  "thiserror",
  "zeroize",
 ]
diff --git a/sntrup-kem/Cargo.toml b/sntrup-kem/Cargo.toml
index fa897a1..64aa83e 100644
--- a/sntrup-kem/Cargo.toml
+++ b/sntrup-kem/Cargo.toml
@@ -27,10 +27,10 @@ serde = ["dep:serdect", "dep:serde"]
 js = ["getrandom/wasm_js"]
 
 [dependencies]
+ctutils = "0.4"
 hex = "0.4"
 rand = "0.10.0"
 rand_chacha = "0.10.0"
-subtle = "2"
 getrandom = { version = "0.4", optional = true }
 hybrid-array = { version = "0.4.14", features = ["extra-sizes"], optional = true }
 kem = { version = "0.3", optional = true }
diff --git a/sntrup-kem/src/types.rs b/sntrup-kem/src/types.rs
index 742a4b6..1710500 100644
--- a/sntrup-kem/src/types.rs
+++ b/sntrup-kem/src/types.rs
@@ -3,7 +3,7 @@
 use crate::error::Error;
 use crate::params::SntrupParams;
 use core::marker::PhantomData;
-use subtle::ConstantTimeEq;
+use ctutils::{Choice, CtEq};
 use zeroize::Zeroize;
 
 /// Streamlined NTRU Prime encapsulation key (public key).
@@ -215,11 +215,11 @@ impl<P: SntrupParams> PartialEq for Ciphertext<P> {
 impl<P: SntrupParams> Eq for Ciphertext<P> {}
 
 // ---------------------------------------------------------------------------
-// ConstantTimeEq / PartialEq / Eq (DecapsulationKey)
+// CtEq / PartialEq / Eq (DecapsulationKey)
 // ---------------------------------------------------------------------------
 
-impl<P: SntrupParams> ConstantTimeEq for DecapsulationKey<P> {
-    fn ct_eq(&self, other: &Self) -> subtle::Choice {
+impl<P: SntrupParams> CtEq for DecapsulationKey<P> {
+    fn ct_eq(&self, other: &Self) -> Choice {
         self.bytes.as_slice().ct_eq(other.bytes.as_slice())
     }
 }
@@ -233,11 +233,11 @@ impl<P: SntrupParams> PartialEq for DecapsulationKey<P> {
 impl<P: SntrupParams> Eq for DecapsulationKey<P> {}
 
 // ---------------------------------------------------------------------------
-// ConstantTimeEq / PartialEq / Eq (SharedSecret)
+// CtEq / PartialEq / Eq (SharedSecret)
 // ---------------------------------------------------------------------------
 
-impl<P: SntrupParams> ConstantTimeEq for SharedSecret<P> {
-    fn ct_eq(&self, other: &Self) -> subtle::Choice {
+impl<P: SntrupParams> CtEq for SharedSecret<P> {
+    fn ct_eq(&self, other: &Self) -> Choice {
         self.bytes.as_slice().ct_eq(other.bytes.as_slice())
     }
 }