feat: add gcp-signer

Cargo.toml

@@ -110,6 +110,7 @@ alloy = { version = "0.7", features = [
     "signer-mnemonic",
     "signer-trezor",
     "signer-yubihsm",
+    "signer-gcp"
 ] }
 
 foundry-fork-db = "0.8"

examples/wallets/Cargo.toml

@@ -14,6 +14,10 @@ workspace = true
 
 [dev-dependencies]
 alloy.workspace = true
+gcloud-sdk = {version = "0.25.0", features = [
+    "google-cloud-kms-v1",
+    "google-longrunning"
+]}
 
 aws-config = { version = "1.5", default-features = false }
 aws-sdk-kms = { version = "1.50", default-features = false }

examples/wallets/examples/gcp_signer.rs

@@ -0,0 +1,32 @@
+//! Example of how to use GCP Ethereum Signer.
+use alloy::signers::gcp::{GcpKeyRingRef, GcpSigner, KeySpecifier};
+use alloy::signers::Signer;
+use gcloud_sdk::{
+    google::cloud::kms::v1::key_management_service_client::KeyManagementServiceClient, GoogleApi,
+};
+
+#[tokio::main]
+async fn main() {
+    // environment variable, preferably to be set in a dotenv file
+    let project_id = "GOOGLE_PROJECT_ID";
+    let location = "GOOGLE_LOCATION";
+    let keyring = "GOOGLE_KEYRING";
+    let key_name = "GOOGLE_KEY_NAME";
+
+    let keyring = GcpKeyRingRef::new(&project_id, &location, &keyring);
+    let client = GoogleApi::from_function(
+        KeyManagementServiceClient::new,
+        "https://cloudkms.googleapis.com",
+        None,
+    )
+    .await
+    .expect("Failed to create GCP KMS Client");
+
+    let key_version = 1;
+
+    let specifier = KeySpecifier::new(keyring, &key_name, key_version);
+    let signer = GcpSigner::new(client, specifier, Some(key_version)).await.expect("get_key");
+    let message = vec![0, 1, 2, 3];
+    let sig = signer.sign_message(&message).await.unwrap();
+    assert_eq!(sig.recover_address_from_msg(message).unwrap(), signer.address());
+}