fix: correct behaviour of functions in the web module to correspond…

… to the one from the `node` module (#46)

package.json

@@ -10,10 +10,11 @@
     "lint": "prettier --check '{src,test}/**/*' README.md package.json",
     "lint:fix": "prettier --write '{src,test}/**/*' README.md package.json",
     "pretest": "npm run -s lint",
-    "test": "npm run -s test:node && npm run -s test:deno && npm run -s test:browser",
+    "test": "npm run -s test:node && npm run -s test:web",
     "test:node": "jest --coverage",
+    "test:web": "npm run test:deno && npm run test:browser",
+    "pretest:web": "npm run -s build",
     "test:deno": "cd test/deno && deno test",
-    "pretest:browser": "npm run -s build",
     "test:browser": "node test/browser-test.js"
   },
   "repository": "github:octokit/webhooks-methods.js",

src/node/sign.ts

@@ -1,16 +1,7 @@
 import { createHmac } from "crypto";
+import { Algorithm, SignOptions } from "../types";
 import { VERSION } from "../version";
 
-export enum Algorithm {
-  SHA1 = "sha1",
-  SHA256 = "sha256",
-}
-
-type SignOptions = {
-  secret: string;
-  algorithm?: Algorithm | "sha1" | "sha256";
-};
-
 export async function sign(
   options: SignOptions | string,
   payload: string

src/node/verify.ts

@@ -3,10 +3,7 @@ import { Buffer } from "buffer";
 
 import { sign } from "./sign";
 import { VERSION } from "../version";
-
-const getAlgorithm = (signature: string) => {
-  return signature.startsWith("sha256=") ? "sha256" : "sha1";
-};
+import { getAlgorithm } from "../utils";
 
 export async function verify(
   secret: string,

src/types.ts

@@ -0,0 +1,11 @@
+export enum Algorithm {
+  SHA1 = "sha1",
+  SHA256 = "sha256",
+}
+
+export type AlgorithmLike = Algorithm | "sha1" | "sha256";
+
+export type SignOptions = {
+  secret: string;
+  algorithm?: AlgorithmLike;
+};

src/utils.ts

@@ -0,0 +1,3 @@
+export const getAlgorithm = (signature: string) => {
+  return signature.startsWith("sha256=") ? "sha256" : "sha1";
+};

src/web.ts

@@ -1,22 +1,7 @@
-const enc = new TextEncoder();
-
-export async function sign(secret: string, data: string) {
-  const signature = await crypto.subtle.sign(
-    "HMAC",
-    await importKey(secret),
-    enc.encode(data)
-  );
-  return UInt8ArrayToHex(signature);
-}
+import { Algorithm, AlgorithmLike, SignOptions } from "./types";
+import { getAlgorithm } from "./utils";
 
-export async function verify(secret: string, data: string, signature: string) {
-  return await crypto.subtle.verify(
-    "HMAC",
-    await importKey(secret),
-    hexToUInt8Array(signature),
-    enc.encode(data)
-  );
-}
+const enc = new TextEncoder();
 
 function hexToUInt8Array(string: string) {
   // convert string to pairs of 2 characters
@@ -36,16 +21,76 @@ function UInt8ArrayToHex(signature: ArrayBuffer) {
     .join("");
 }
 
-async function importKey(secret: string) {
+function getHMACHashName(algorithm: AlgorithmLike) {
+  return (
+    {
+      [Algorithm.SHA1]: "SHA-1",
+      [Algorithm.SHA256]: "SHA-256",
+    } as { [key in Algorithm]: string }
+  )[algorithm];
+}
+
+async function importKey(secret: string, algorithm: AlgorithmLike) {
+  // ref: https://developer.mozilla.org/en-US/docs/Web/API/HmacImportParams
   return crypto.subtle.importKey(
     "raw", // raw format of the key - should be Uint8Array
     enc.encode(secret),
     {
       // algorithm details
       name: "HMAC",
-      hash: { name: "SHA-256" },
+      hash: { name: getHMACHashName(algorithm) },
     },
     false, // export = false
     ["sign", "verify"] // what this key can do
   );
 }
+
+export async function sign(options: SignOptions | string, payload: string) {
+  const { secret, algorithm } =
+    typeof options === "object"
+      ? {
+          secret: options.secret,
+          algorithm: options.algorithm || Algorithm.SHA256,
+        }
+      : { secret: options, algorithm: Algorithm.SHA256 };
+
+  if (!secret || !payload) {
+    throw new TypeError(
+      "[@octokit/webhooks-methods] secret & payload required for sign()"
+    );
+  }
+
+  if (!Object.values(Algorithm).includes(algorithm as Algorithm)) {
+    throw new TypeError(
+      `[@octokit/webhooks] Algorithm ${algorithm} is not supported. Must be  'sha1' or 'sha256'`
+    );
+  }
+
+  const signature = await crypto.subtle.sign(
+    "HMAC",
+    await importKey(secret, algorithm),
+    enc.encode(payload)
+  );
+
+  return `${algorithm}=${UInt8ArrayToHex(signature)}`;
+}
+
+export async function verify(
+  secret: string,
+  eventPayload: string,
+  signature: string
+) {
+  if (!secret || !eventPayload || !signature) {
+    throw new TypeError(
+      "[@octokit/webhooks-methods] secret, eventPayload & signature required"
+    );
+  }
+
+  const algorithm = getAlgorithm(signature);
+  return await crypto.subtle.verify(
+    "HMAC",
+    await importKey(secret, algorithm),
+    hexToUInt8Array(signature.replace(`${algorithm}=`, "")),
+    enc.encode(eventPayload)
+  );
+}

test/browser-test.js

@@ -27,7 +27,7 @@ async function runTests() {
 
   strictEqual(
     signature,
-    "1b2c16b75bd2a870c114153ccda5bcfca63314bc722fa160d690de133ccbb9db"
+    "sha256=1b2c16b75bd2a870c114153ccda5bcfca63314bc722fa160d690de133ccbb9db"
   );
   strictEqual(verified, true);
 

test/deno/web.test.ts

@@ -1,17 +1,17 @@
-import { sign, verify } from "../../src/web.ts";
+import { sign, verify } from "../../pkg/dist-web/index.js";
 
 import { assertEquals } from "std/testing/asserts.ts";
 
 Deno.test("sign", async () => {
   const actual = await sign("secret", "data");
   const expected =
-    "1b2c16b75bd2a870c114153ccda5bcfca63314bc722fa160d690de133ccbb9db";
+    "sha256=1b2c16b75bd2a870c114153ccda5bcfca63314bc722fa160d690de133ccbb9db";
   assertEquals(actual, expected);
 });
 
 Deno.test("verify", async () => {
   const signature =
-    "1b2c16b75bd2a870c114153ccda5bcfca63314bc722fa160d690de133ccbb9db";
+    "sha256=1b2c16b75bd2a870c114153ccda5bcfca63314bc722fa160d690de133ccbb9db";
   const actual = await verify("secret", "data", signature);
   const expected = true;
   assertEquals(actual, expected);