Replace http-message-sig with fetch-message-signatures in the web-bot-auth package

examples/browser-extension/src/background.ts

@@ -1,5 +1,6 @@
 import {
   Algorithm,
+  KeyedSigner,
   signatureHeadersSync,
   helpers,
   jwkToKeyID,
@@ -18,39 +19,37 @@ const MAX_AGE_IN_MS = 1000 * 60 * 60; // 1 hour
 const SIGNATURE_AGENT =
   "https://http-message-signatures-example.research.cloudflare.com";
 
-class Ed25519Signer {
-  public alg: Algorithm = "ed25519";
-  public keyid: string;
-  private privateKey: Uint8Array<ArrayBuffer>;
+// libsodium signs synchronously, which is what a blocking listener needs. A signer may return the
+// signature directly rather than a Promise of it, so no wrapper is involved.
+function ed25519Signer(jwk: JsonWebKey): KeyedSigner {
+  const sodium = _sodium;
 
-  constructor(public jwk: JsonWebKey) {
-    const sodium = _sodium;
+  // Base64URL decode helper
+  const base64urlDecode = (str) =>
+    sodium.from_base64(str, sodium.base64_variants.URLSAFE_NO_PADDING);
 
-    // Base64URL decode helper
-    const base64urlDecode = (str) =>
-      sodium.from_base64(str, sodium.base64_variants.URLSAFE_NO_PADDING);
+  // Decode keys
+  const privateKey = base64urlDecode(jwk.d); // 32 bytes
+  const publicKey = base64urlDecode(jwk.x); // 32 bytes
 
-    // Decode keys
-    const privateKey = base64urlDecode(jwk.d); // 32 bytes
-    const publicKey = base64urlDecode(jwk.x); // 32 bytes
-
-    // Build the full 64-byte secret key: privateKey || publicKey
-    const fullSecretKey = new Uint8Array(64);
-    fullSecretKey.set(privateKey);
-    fullSecretKey.set(publicKey, 32);
-
-    this.privateKey = fullSecretKey;
+  // Build the full 64-byte secret key: privateKey || publicKey
+  const fullSecretKey = new Uint8Array(64);
+  fullSecretKey.set(privateKey);
+  fullSecretKey.set(publicKey, 32);
 
+  const alg: Algorithm = "ed25519";
+  return {
+    alg,
     // NOTE: this MUST be computed from the public key bytes. It just so happen Chrome does not easily allow to perform a sha256 synchronously
-    this.keyid = KEY_ID;
-  }
-
-  signSync(data: string): Uint8Array {
-    const sodium = _sodium;
-    const message = sodium.from_string(data);
-    const signedMessage = sodium.crypto_sign(message, this.privateKey);
-    return signedMessage.slice(0, sodium.crypto_sign_BYTES);
-  }
+    keyid: KEY_ID,
+    signer: () => ({
+      alg,
+      sign: (data) =>
+        sodium
+          .crypto_sign(data, fullSecretKey)
+          .slice(0, sodium.crypto_sign_BYTES),
+    }),
+  };
 }
 
 chrome.webRequest.onBeforeSendHeaders.addListener(
@@ -66,7 +65,7 @@ chrome.webRequest.onBeforeSendHeaders.addListener(
       headers: details.requestHeaders?.map((h) => [h.name, h.value!])!,
     });
     const now = new Date();
-    const headers = signatureHeadersSync(request, new Ed25519Signer(jwk), {
+    const headers = signatureHeadersSync(request, ed25519Signer(jwk), {
       components: recommendedComponents("sig1"),
       created: now,
       expires: new Date(now.getTime() + MAX_AGE_IN_MS),

examples/verification-workers/src/index.ts

@@ -19,7 +19,7 @@ import {
 	Signer,
 	SignatureAgentCard,
 	SignatureAgentEntry,
-	VerificationParams,
+	VerifierFactory,
 	directoryResponseHeaders,
 	helpers,
 	jwkToKeyID,
@@ -34,7 +34,7 @@ import { generateDebugHTML } from "./debug-html";
 import { invalidHTML, neutralHTML, validHTML } from "./index-html";
 import { proxyDirectoryRequest } from "./proxy-directory";
 import jwk from "../../rfc9421-keys/ed25519.json" assert { type: "json" };
-import { Ed25519Signer } from "web-bot-auth/crypto";
+import { signerFromJWK, verifier } from "web-bot-auth/crypto";
 
 function errorMessage(error: unknown): string {
 	return error instanceof Error ? error.message : String(error);
@@ -164,39 +164,22 @@ async function fetchDirectory(entry: SignatureAgentEntry): Promise<Directory> {
 }
 
 async function getSigner(): Promise<Signer> {
-	return Ed25519Signer.fromJWK(jwk);
+	return signerFromJWK(jwk);
 }
 
-function verifyEd25519(
-	directory: Directory
-): (
-	data: string,
-	signature: Uint8Array,
-	params: VerificationParams
-) => Promise<void> {
-	return async (data, signature, _params) => {
-		void _params;
-		const key = await crypto.subtle.importKey(
-			"jwk",
-			directory.keys[0],
-			{ name: "Ed25519" },
-			true,
-			["verify"]
-		);
-
-		const encodedData = new TextEncoder().encode(data);
-
-		const isValid = await crypto.subtle.verify(
-			{ name: "Ed25519" },
-			key,
-			signature,
-			encodedData
-		);
-
-		if (!isValid) {
-			throw new Error("invalid signature");
-		}
-	};
+function verifyEd25519(directory: Directory): VerifierFactory {
+	// Awaited inside the factory, which may return a Promise so that key material can be resolved
+	// per signature rather than once up front.
+	return async (signature, context) =>
+		verifier(
+			await crypto.subtle.importKey(
+				"jwk",
+				directory.keys[0],
+				{ name: "Ed25519" },
+				true,
+				["verify"]
+			)
+		)(signature, context);
 }
 
 const SignatureValidationStatus = {