From 18df062a099811355cafc2024e30a7c2b68c7984 Mon Sep 17 00:00:00 2001
From: Adam Soltys <adam@coinos.io>
Date: Thu, 26 Feb 2026 16:07:52 -0800
Subject: client side password auth

---
 src/lib/deriveAuthKey.ts | 23 +++++++++++++++++++++++
 src/lib/utils.ts         | 12 ++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 src/lib/deriveAuthKey.ts

(limited to 'src/lib')

diff --git a/src/lib/deriveAuthKey.ts b/src/lib/deriveAuthKey.ts
new file mode 100644
index 00000000..9215b515
--- /dev/null
+++ b/src/lib/deriveAuthKey.ts
@@ -0,0 +1,23 @@
+import { scryptAsync } from "@noble/hashes/scrypt.js";
+import { bytesToHex } from "@noble/hashes/utils.js";
+import { getPublicKey } from "nostr-tools";
+import { rememberPrfKey, defaultRememberForMs } from "$lib/passwordCache";
+
+export async function deriveAuthKeypair(username: string, password: string) {
+  const salt = `coinos:auth:${username.toLowerCase().replace(/\s/g, "")}`;
+  const sk = await scryptAsync(password, salt, { N: 2 ** 16, r: 8, p: 1, dkLen: 32 });
+  const pubkey = getPublicKey(sk);
+  return { sk, pubkey, skHex: bytesToHex(sk) };
+}
+
+export async function deriveWalletEntropy(sk: Uint8Array): Promise<ArrayBuffer> {
+  const { finalizeEvent } = await import("nostr-tools");
+  const event = { kind: 1, created_at: 0, content: "coinos-wallet-key-derivation", tags: [] };
+  const signed = finalizeEvent(event as any, sk);
+  const sigBytes = new Uint8Array(signed.sig.length / 2);
+  for (let i = 0; i < signed.sig.length; i += 2)
+    sigBytes[i / 2] = parseInt(signed.sig.slice(i, i + 2), 16);
+  const entropy = await crypto.subtle.digest("SHA-256", sigBytes);
+  rememberPrfKey(entropy, defaultRememberForMs);
+  return entropy;
+}
diff --git a/src/lib/utils.ts b/src/lib/utils.ts
index 4bf96d6e..eee6903e 100644
--- a/src/lib/utils.ts
+++ b/src/lib/utils.ts
@@ -164,6 +164,7 @@ export const login = async (
     token?: string;
     challenge?: string;
     recaptcha?: string;
+    authPubkey?: string;
   },
   cookies,
   ip: string,
@@ -509,6 +510,17 @@ export const register = async (
   };
   if (ip) headers["cf-connecting-ip"] = ip;
 
+  // Derive authPubkey if password provided
+  if (user.password && user.username) {
+    try {
+      const { deriveAuthKeypair } = await import("$lib/deriveAuthKey");
+      const { pubkey: authPubkey } = await deriveAuthKeypair(user.username, user.password);
+      user.authPubkey = authPubkey;
+    } catch (e) {
+      console.log("Failed to derive authPubkey during registration", e);
+    }
+  }
+
   let sk, token;
   try {
     ({ sk, token } = await post("/register", { user }, headers));
-- 
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