MLS implementation

utils.ts

@@ -8,6 +8,7 @@ import {
   encryptionKey,
   encryptUint8Array,
 } from "./utils/encryption.ts";
+import { NSec } from "@nostr/tools/nip19";
 
 export function isLocalhost(req: Request): boolean {
   const url = new URL(req.url);
@@ -61,9 +62,52 @@ export async function getCCNPubkey(): Promise<string> {
   return ccnPublicKey;
 }
 
+export async function getMLSPrivateKey(): Promise<NSec> {
+  const mlsPrivPath = await getEveFilePath("mls.priv");
+  const doWeHaveKey = await exists(mlsPrivPath);
+  if (doWeHaveKey) {
+    const encryptedPrivateKey = Deno.readTextFileSync(mlsPrivPath);
+    const decryptedPrivateKey = decryptUint8Array(
+      decodeBase64(encryptedPrivateKey),
+      encryptionKey,
+    );
+    return nostrTools.nip19.nsecEncode(decryptedPrivateKey);
+  }
+  const mlsPrivateKey = nostrTools.generateSecretKey();
+  const encryptedPrivateKey = encryptUint8Array(mlsPrivateKey, encryptionKey);
+  Deno.writeTextFileSync(mlsPrivPath, encodeBase64(encryptedPrivateKey));
+  return nostrTools.nip19.nsecEncode(mlsPrivateKey);
+}
+
 export async function getCCNPrivateKey(): Promise<Uint8Array> {
   const encryptedPrivateKey = Deno.readTextFileSync(
     await getEveFilePath("ccn.priv"),
   );
   return decryptUint8Array(decodeBase64(encryptedPrivateKey), encryptionKey);
 }
+
+/**
+ * Compares two byte-like objects in a constant-time manner to prevent timing attacks.
+ *
+ * @param a - First byte-like object to compare
+ * @param b - Second byte-like object to compare
+ * @returns boolean indicating whether the inputs contain identical bytes
+ */
+export function bytesEqual<
+  T extends Uint8Array | number[] | string,
+>(a: T, b: T): boolean {
+  const aLength = a.length;
+  const bLength = b.length;
+  let result = aLength !== bLength ? 1 : 0;
+  const maxLength = Math.max(aLength, bLength);
+  for (let i = 0; i < maxLength; i++) {
+    const aVal = i < aLength
+      ? (typeof a === "string" ? a.charCodeAt(i) : a[i])
+      : 0;
+    const bVal = i < bLength
+      ? (typeof b === "string" ? b.charCodeAt(i) : b[i])
+      : 0;
+    result |= aVal ^ bVal;
+  }
+  return result === 0;
+}