nostr key derivation

2 files changed, 73 insertions, 6 deletions

diff --git a/src/lib/passwordCache.ts b/src/lib/passwordCache.ts
index 98272e0f..0ed36af1 100644
--- a/src/lib/passwordCache.ts
+++ b/src/lib/passwordCache.ts
@@ -5,12 +5,12 @@ const PASSWORD_KEY = "walletPassword";
 const EXPIRES_KEY = "walletPasswordExpiresAt";
 
 export const rememberForOptions = [
-  { label: "Don't remember", ms: 0 },
-  { label: "8 hours", ms: 8 * 60 * 60 * 1000 },
-  { label: "1 day", ms: 24 * 60 * 60 * 1000 },
-  { label: "1 week", ms: 7 * 24 * 60 * 60 * 1000 },
-  { label: "1 month", ms: 30 * 24 * 60 * 60 * 1000 },
-  { label: "1 year", ms: 365 * 24 * 60 * 60 * 1000 },
+  { label: "user.settings.dontRemember", ms: 0 },
+  { label: "user.settings.8hours", ms: 8 * 60 * 60 * 1000 },
+  { label: "user.settings.1day", ms: 24 * 60 * 60 * 1000 },
+  { label: "user.settings.1week", ms: 7 * 24 * 60 * 60 * 1000 },
+  { label: "user.settings.1month", ms: 30 * 24 * 60 * 60 * 1000 },
+  { label: "user.settings.1year", ms: 365 * 24 * 60 * 60 * 1000 },
 ];
 
 export const defaultRememberForMs = 30 * 24 * 60 * 60 * 1000;
diff --git a/src/lib/walletEntropy.ts b/src/lib/walletEntropy.ts
new file mode 100644
index 00000000..f022a2cc
--- /dev/null
+++ b/src/lib/walletEntropy.ts
@@ -0,0 +1,67 @@
+import { browser } from "$app/environment";
+import { getCachedPrfKey, rememberPrfKey, defaultRememberForMs } from "$lib/passwordCache";
+
+const DERIVATION_EVENT = {
+  kind: 1,
+  created_at: 0,
+  content: "coinos-wallet-key-derivation",
+  tags: [],
+};
+
+async function hashSignature(sig: string): Promise<ArrayBuffer> {
+  const sigBytes = new Uint8Array(sig.length / 2);
+  for (let i = 0; i < sig.length; i += 2)
+    sigBytes[i / 2] = parseInt(sig.slice(i, i + 2), 16);
+  return crypto.subtle.digest("SHA-256", sigBytes);
+}
+
+/**
+ * Silent helper. Checks localStorage for nsec, signs fixed event locally,
+ * caches and returns entropy. Returns null if no nsec stored.
+ */
+export async function tryDeriveFromNsec(): Promise<ArrayBuffer | null> {
+  if (!browser) return null;
+  const nsec = localStorage.getItem("nsec");
+  if (!nsec) return null;
+
+  try {
+    const { nip19, finalizeEvent } = await import("nostr-tools");
+    const sk = nip19.decode(nsec).data as Uint8Array;
+    const signed = finalizeEvent({ ...DERIVATION_EVENT } as any, sk);
+    const entropy = await hashSignature(signed.sig);
+    rememberPrfKey(entropy, defaultRememberForMs);
+    return entropy;
+  } catch (e) {
+    console.log("nsec entropy derivation failed", e);
+    return null;
+  }
+}
+
+/**
+ * Non-interactive. Checks cached prfKey, then tries silent nsec derivation.
+ * Returns null if neither available. Use in onMount and auto-provisioning.
+ */
+export async function getWalletEntropy(): Promise<ArrayBuffer | null> {
+  const cached = getCachedPrfKey();
+  if (cached) return cached;
+  return tryDeriveFromNsec();
+}
+
+/**
+ * Interactive. Tries silent nsec first, then calls sign() from $lib/nostr
+ * which shows Nostr.svelte modal if signer isn't ready. Caches result.
+ * Use for "Unlock" buttons.
+ */
+export async function deriveNostrEntropy(): Promise<ArrayBuffer> {
+  const cached = getCachedPrfKey();
+  if (cached) return cached;
+
+  const fromNsec = await tryDeriveFromNsec();
+  if (fromNsec) return fromNsec;
+
+  const { sign } = await import("$lib/nostr");
+  const signed = await sign({ ...DERIVATION_EVENT });
+  const entropy = await hashSignature(signed.sig);
+  rememberPrfKey(entropy, defaultRememberForMs);
+  return entropy;
+}