From 3cdc1536c5e6ea205c3586414ba69c91e256a97b Mon Sep 17 00:00:00 2001
From: Luke Parker <lukeparker5132@gmail.com>
Date: Thu, 13 Nov 2025 05:44:52 -0500
Subject: [PATCH] Make `ethereum-schnorr-contract` no-`std` and no-`alloc`
 eligible

---
 networks/ethereum/schnorr/Cargo.toml       | 15 +++++++++++----
 networks/ethereum/schnorr/src/lib.rs       |  1 +
 networks/ethereum/schnorr/src/signature.rs |  3 ++-
 processor/ethereum/router/Cargo.toml       |  2 +-
 tests/no-std/Cargo.toml                    |  4 ++++
 tests/no-std/src/lib.rs                    |  2 ++
 6 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/networks/ethereum/schnorr/Cargo.toml b/networks/ethereum/schnorr/Cargo.toml
index bfe88776..f927557d 100644
--- a/networks/ethereum/schnorr/Cargo.toml
+++ b/networks/ethereum/schnorr/Cargo.toml
@@ -16,10 +16,12 @@ rustdoc-args = ["--cfg", "docsrs"]
 workspace = true
 
 [dependencies]
-subtle = { version = "2", default-features = false, features = ["std"] }
-sha3 = { version = "0.10", default-features = false, features = ["std"] }
-group = { version = "0.13", default-features = false, features = ["alloc"] }
-k256 = { version = "^0.13.1", default-features = false, features = ["std", "arithmetic"] }
+std-shims = { path = "../../../common/std-shims", version = "0.1", default-features = false }
+
+subtle = { version = "2", default-features = false }
+sha3 = { version = "0.10", default-features = false }
+group = { version = "0.13", default-features = false }
+k256 = { version = "^0.13.1", default-features = false, features = ["arithmetic"] }
 
 [build-dependencies]
 build-solidity-contracts = { path = "../build-contracts", version = "0.1" }
@@ -40,3 +42,8 @@ alloy-provider = { version = "1", default-features = false }
 alloy-node-bindings = { version = "1", default-features = false }
 
 tokio = { version = "1", default-features = false, features = ["macros"] }
+
+[features]
+alloc = ["std-shims/alloc", "group/alloc"]
+std = ["alloc", "std-shims/std", "subtle/std", "sha3/std", "k256/std"]
+default = ["std"]
diff --git a/networks/ethereum/schnorr/src/lib.rs b/networks/ethereum/schnorr/src/lib.rs
index bcef5fd9..a0cc6e07 100644
--- a/networks/ethereum/schnorr/src/lib.rs
+++ b/networks/ethereum/schnorr/src/lib.rs
@@ -2,6 +2,7 @@
 #![doc = include_str!("../README.md")]
 #![deny(missing_docs)]
 #![allow(non_snake_case)]
+#![cfg_attr(not(feature = "std"), no_std)]
 
 mod public_key;
 pub use public_key::PublicKey;
diff --git a/networks/ethereum/schnorr/src/signature.rs b/networks/ethereum/schnorr/src/signature.rs
index 105e6d4d..a3766a85 100644
--- a/networks/ethereum/schnorr/src/signature.rs
+++ b/networks/ethereum/schnorr/src/signature.rs
@@ -1,4 +1,4 @@
-use std::io;
+use std_shims::io;
 
 use sha3::{Digest, Keccak256};
 
@@ -77,6 +77,7 @@ impl Signature {
   }
 
   /// Write the signature.
+  #[cfg(feature = "alloc")]
   pub fn write(&self, writer: &mut impl io::Write) -> io::Result<()> {
     writer.write_all(&self.to_bytes())
   }
diff --git a/processor/ethereum/router/Cargo.toml b/processor/ethereum/router/Cargo.toml
index 133f7610..404f4aa1 100644
--- a/processor/ethereum/router/Cargo.toml
+++ b/processor/ethereum/router/Cargo.toml
@@ -35,7 +35,7 @@ alloy-provider = { version = "1", default-features = false }
 
 revm = { version = "33", default-features = false }
 
-ethereum-schnorr = { package = "ethereum-schnorr-contract", path = "../../../networks/ethereum/schnorr", default-features = false }
+ethereum-schnorr = { package = "ethereum-schnorr-contract", path = "../../../networks/ethereum/schnorr", default-features = false, features = ["std"] }
 
 ethereum-primitives = { package = "serai-processor-ethereum-primitives", path = "../primitives", default-features = false }
 ethereum-deployer = { package = "serai-processor-ethereum-deployer", path = "../deployer", default-features = false }
diff --git a/tests/no-std/Cargo.toml b/tests/no-std/Cargo.toml
index 2552d7aa..f0c35b1b 100644
--- a/tests/no-std/Cargo.toml
+++ b/tests/no-std/Cargo.toml
@@ -46,6 +46,8 @@ frost-schnorrkel = { path = "../../crypto/schnorrkel", default-features = false,
 
 bitcoin-serai = { path = "../../networks/bitcoin", default-features = false, features = ["hazmat"], optional = true }
 
+ethereum-schnorr-contract = { path = "../../networks/ethereum/schnorr", default-features = false }
+
 [features]
 alloc = [
   "std-shims/alloc",
@@ -75,4 +77,6 @@ alloc = [
   "frost-schnorrkel",
 
   "bitcoin-serai",
+
+  "ethereum-schnorr-contract/alloc",
 ]
diff --git a/tests/no-std/src/lib.rs b/tests/no-std/src/lib.rs
index 320a3c87..334196fa 100644
--- a/tests/no-std/src/lib.rs
+++ b/tests/no-std/src/lib.rs
@@ -16,6 +16,8 @@ pub use embedwards25519;
 
 pub use schnorr_signatures;
 
+pub use ethereum_schnorr_contract;
+
 #[cfg(feature = "alloc")]
 pub mod alloc {
   pub use multiexp;