From 0d906363a08ff3b3be8fe8c98ca91706e1264b45 Mon Sep 17 00:00:00 2001
From: Luke Parker <lukeparker5132@gmail.com>
Date: Sat, 18 Jan 2025 15:13:39 -0500
Subject: [PATCH] Simplify and test deterministically_sign
---
processor/ethereum/TODO/old_processor.rs | 2 +-
processor/ethereum/TODO/tests/mod.rs | 2 +-
processor/ethereum/deployer/src/lib.rs | 7 +-
processor/ethereum/primitives/src/lib.rs | 70 ++++++++++++++-----
processor/ethereum/router/src/tests/mod.rs | 14 ++--
processor/ethereum/test-primitives/src/lib.rs | 2 +-
6 files changed, 66 insertions(+), 31 deletions(-)
diff --git a/processor/ethereum/TODO/old_processor.rs b/processor/ethereum/TODO/old_processor.rs
index a7e85a5c..f95b8225 100644
--- a/processor/ethereum/TODO/old_processor.rs
+++ b/processor/ethereum/TODO/old_processor.rs
@@ -26,7 +26,7 @@ TODO
};
tx.gas_limit = 1_000_000u64.into();
tx.gas_price = 1_000_000_000u64.into();
- let tx = ethereum_serai::crypto::deterministically_sign(&tx);
+ let tx = ethereum_serai::crypto::deterministically_sign(tx);
if self.provider.get_transaction_by_hash(*tx.hash()).await.unwrap().is_none() {
self
diff --git a/processor/ethereum/TODO/tests/mod.rs b/processor/ethereum/TODO/tests/mod.rs
index a865868f..be9106d5 100644
--- a/processor/ethereum/TODO/tests/mod.rs
+++ b/processor/ethereum/TODO/tests/mod.rs
@@ -109,7 +109,7 @@ pub async fn deploy_contract(
input: bin,
};
- let deployment_tx = deterministically_sign(&deployment_tx);
+ let deployment_tx = deterministically_sign(deployment_tx);
// Fund the deployer address
fund_account(
diff --git a/processor/ethereum/deployer/src/lib.rs b/processor/ethereum/deployer/src/lib.rs
index 58b0262d..a4d6ed94 100644
--- a/processor/ethereum/deployer/src/lib.rs
+++ b/processor/ethereum/deployer/src/lib.rs
@@ -43,10 +43,13 @@ impl Deployer {
let bytecode =
Bytes::from_hex(BYTECODE).expect("compiled-in Deployer bytecode wasn't valid hex");
+ // Legacy transactions are used to ensure the widest possible degree of support across EVMs
let tx = TxLegacy {
chain_id: None,
nonce: 0,
- // 100 gwei
+ // This uses a fixed gas price as necessary to achieve a deterministic address
+ // The gas price is fixed to 100 gwei, which should be incredibly generous, in order to make
+ // this getting stuck unlikely. While expensive, this only has to occur once
gas_price: 100_000_000_000u128,
// TODO: Use a more accurate gas limit
gas_limit: 1_000_000u64,
@@ -55,7 +58,7 @@ impl Deployer {
input: bytecode,
};
- ethereum_primitives::deterministically_sign(&tx)
+ ethereum_primitives::deterministically_sign(tx)
}
/// Obtain the deterministic address for this contract.
diff --git a/processor/ethereum/primitives/src/lib.rs b/processor/ethereum/primitives/src/lib.rs
index a6da3b4d..eb7bd615 100644
--- a/processor/ethereum/primitives/src/lib.rs
+++ b/processor/ethereum/primitives/src/lib.rs
@@ -15,34 +15,66 @@ pub fn keccak256(data: impl AsRef<[u8]>) -> [u8; 32] {
/// Deterministically sign a transaction.
///
-/// This signs a transaction via setting `r = 1, s = 1`, and incrementing `r` until a signer is
-/// recoverable from the signature for this transaction. The purpose of this is to be able to send
-/// a transaction from a known account which no one knows the private key for.
+/// This signs a transaction via setting a signature of `r = 1, s = 1`. The purpose of this is to
+/// be able to send a transaction from an account which no one knows the private key for and no
+/// other messages may be signed for from.
///
/// This function panics if passed a transaction with a non-None chain ID. This is because the
/// signer for this transaction is only singular across any/all EVM instances if it isn't binding
/// to an instance.
-pub fn deterministically_sign(tx: &TxLegacy) -> Signed<TxLegacy> {
+pub fn deterministically_sign(tx: TxLegacy) -> Signed<TxLegacy> {
assert!(
tx.chain_id.is_none(),
"chain ID was Some when deterministically signing a TX (causing a non-singular signer)"
);
- let mut r = Scalar::ONE;
+ /*
+ ECDSA signatures are:
+ - x = private key
+ - k = rand()
+ - R = k * G
+ - r = R.x()
+ - s = (H(m) + (r * x)) * k.invert()
+
+ Key recovery is performed via:
+ - a = s * R = (H(m) + (r * x)) * G
+ - b = a - (H(m) * G) = (r * x) * G
+ - X = b / r = x * G
+ - X = ((s * R) - (H(m) * G)) * r.invert()
+
+ This requires `r` be non-zero and `R` be recoverable from `r` and the parity byte. For
+ `r = 1, s = 1`, this sets `X` to `R - (H(m) * G)`. Since there is an `R` recoverable for
+ `r = 1`, since the `R` is a point with an unknown discrete logarithm w.r.t. the generator, and
+ since the resulting key is dependent on the message signed for, this will always work to
+ the specification.
+ */
+
+ let r = Scalar::ONE;
let s = Scalar::ONE;
- loop {
- // Create the signature
- let r_bytes: [u8; 32] = r.to_repr().into();
- let s_bytes: [u8; 32] = s.to_repr().into();
- let signature =
- PrimitiveSignature::from_scalars_and_parity(r_bytes.into(), s_bytes.into(), false);
+ let r_bytes: [u8; 32] = r.to_repr().into();
+ let s_bytes: [u8; 32] = s.to_repr().into();
+ let signature =
+ PrimitiveSignature::from_scalars_and_parity(r_bytes.into(), s_bytes.into(), false);
- // Check if this is a valid signature
- let tx = tx.clone().into_signed(signature);
- if tx.recover_signer().is_ok() {
- return tx;
- }
-
- r += Scalar::ONE;
- }
+ let res = tx.into_signed(signature);
+ debug_assert!(res.recover_signer().is_ok());
+ res
+}
+
+#[test]
+fn test_deterministically_sign() {
+ let tx = TxLegacy { chain_id: None, ..Default::default() };
+ let signed = deterministically_sign(tx.clone());
+
+ assert!(signed.recover_signer().is_ok());
+ let one = alloy_core::primitives::U256::from(1u64);
+ assert_eq!(signed.signature().r(), one);
+ assert_eq!(signed.signature().s(), one);
+
+ let mut other_tx = tx.clone();
+ other_tx.nonce += 1;
+ // Signing a distinct message should yield a distinct signer
+ assert!(
+ signed.recover_signer().unwrap() != deterministically_sign(other_tx).recover_signer().unwrap()
+ );
}
diff --git a/processor/ethereum/router/src/tests/mod.rs b/processor/ethereum/router/src/tests/mod.rs
index e5f8f41e..601d2dfa 100644
--- a/processor/ethereum/router/src/tests/mod.rs
+++ b/processor/ethereum/router/src/tests/mod.rs
@@ -84,7 +84,7 @@ async fn setup_test(
// Set a gas price (100 gwei)
tx.gas_price = 100_000_000_000;
// Sign it
- let tx = ethereum_primitives::deterministically_sign(&tx);
+ let tx = ethereum_primitives::deterministically_sign(tx);
// Publish it
let receipt = ethereum_test_primitives::publish_tx(&provider, tx).await;
assert!(receipt.status());
@@ -123,7 +123,7 @@ async fn confirm_next_serai_key(
let mut tx = router.confirm_next_serai_key(&sig);
tx.gas_price = 100_000_000_000;
- let tx = ethereum_primitives::deterministically_sign(&tx);
+ let tx = ethereum_primitives::deterministically_sign(tx);
let receipt = ethereum_test_primitives::publish_tx(provider, tx).await;
assert!(receipt.status());
assert_eq!(
@@ -164,7 +164,7 @@ async fn test_update_serai_key() {
let mut tx = router.update_serai_key(&update_to, &sig);
tx.gas_price = 100_000_000_000;
- let tx = ethereum_primitives::deterministically_sign(&tx);
+ let tx = ethereum_primitives::deterministically_sign(tx);
let receipt = ethereum_test_primitives::publish_tx(&provider, tx).await;
assert!(receipt.status());
assert_eq!(u128::from(Router::UPDATE_SERAI_KEY_GAS), ((receipt.gas_used + 1000) / 1000) * 1000);
@@ -199,7 +199,7 @@ async fn test_eth_in_instruction() {
.abi_encode()
.into(),
};
- let tx = ethereum_primitives::deterministically_sign(&tx);
+ let tx = ethereum_primitives::deterministically_sign(tx);
let signer = tx.recover_signer().unwrap();
let receipt = ethereum_test_primitives::publish_tx(&provider, tx).await;
@@ -250,7 +250,7 @@ async fn publish_outs(
let mut tx = router.execute(coin, fee, outs, &sig);
tx.gas_price = 100_000_000_000;
- let tx = ethereum_primitives::deterministically_sign(&tx);
+ let tx = ethereum_primitives::deterministically_sign(tx);
ethereum_test_primitives::publish_tx(provider, tx).await
}
@@ -307,7 +307,7 @@ async fn escape_hatch(
let mut tx = router.escape_hatch(escape_to, &sig);
tx.gas_price = 100_000_000_000;
- let tx = ethereum_primitives::deterministically_sign(&tx);
+ let tx = ethereum_primitives::deterministically_sign(tx);
let receipt = ethereum_test_primitives::publish_tx(provider, tx).await;
assert!(receipt.status());
assert_eq!(u128::from(Router::ESCAPE_HATCH_GAS), ((receipt.gas_used + 1000) / 1000) * 1000);
@@ -321,7 +321,7 @@ async fn escape(
) -> TransactionReceipt {
let mut tx = router.escape(coin.address());
tx.gas_price = 100_000_000_000;
- let tx = ethereum_primitives::deterministically_sign(&tx);
+ let tx = ethereum_primitives::deterministically_sign(tx);
let receipt = ethereum_test_primitives::publish_tx(provider, tx).await;
assert!(receipt.status());
receipt
diff --git a/processor/ethereum/test-primitives/src/lib.rs b/processor/ethereum/test-primitives/src/lib.rs
index 9f43d0a2..47cc983e 100644
--- a/processor/ethereum/test-primitives/src/lib.rs
+++ b/processor/ethereum/test-primitives/src/lib.rs
@@ -76,7 +76,7 @@ pub async fn deploy_contract(
input: bin.into(),
};
- let deployment_tx = deterministically_sign(&deployment_tx);
+ let deployment_tx = deterministically_sign(deployment_tx);
let receipt = publish_tx(provider, deployment_tx).await;
assert!(receipt.status());