feat: phase 4 completed

src/lib/crypto.ts

@@ -0,0 +1,96 @@
+export async function deriveKeyFromPassword(password: string): Promise<string> {
+  const encoder = new TextEncoder();
+  const keyMaterial = await crypto.subtle.importKey(
+    "raw",
+    encoder.encode(password),
+    "PBKDF2",
+    false,
+    ["deriveBits", "deriveKey"]
+  );
+  const key = await crypto.subtle.deriveKey(
+    {
+      name: "PBKDF2",
+      salt: encoder.encode("dead-man-switch-salt"),
+      iterations: 100000,
+      hash: "SHA-256",
+    },
+    keyMaterial,
+    { name: "AES-GCM", length: 256 },
+    true,
+    ["encrypt", "decrypt"]
+  );
+  const exported = await crypto.subtle.exportKey("raw", key);
+  return btoa(String.fromCharCode(...new Uint8Array(exported)));
+}
+
+export async function generateKey(): Promise<string> {
+  const key = await crypto.subtle.generateKey(
+    { name: "AES-GCM", length: 256 },
+    true,
+    ["encrypt", "decrypt"]
+  );
+  const exported = await crypto.subtle.exportKey("raw", key);
+  return btoa(String.fromCharCode(...new Uint8Array(exported)));
+}
+
+export async function importKey(keyString: string): Promise<CryptoKey> {
+  const keyData = Uint8Array.from(atob(keyString), (c) => c.charCodeAt(0));
+  return crypto.subtle.importKey(
+    "raw",
+    keyData,
+    { name: "AES-GCM", length: 256 },
+    false,
+    ["encrypt", "decrypt"]
+  );
+}
+
+export async function encrypt(data: string, keyString: string): Promise<string> {
+  const key = await importKey(keyString);
+  const iv = crypto.getRandomValues(new Uint8Array(12));
+  const encoded = new TextEncoder().encode(data);
+  const encrypted = await crypto.subtle.encrypt(
+    { name: "AES-GCM", iv },
+    key,
+    encoded
+  );
+  const combined = new Uint8Array(iv.length + encrypted.byteLength);
+  combined.set(iv);
+  combined.set(new Uint8Array(encrypted), iv.length);
+  return btoa(String.fromCharCode(...combined));
+}
+
+export async function decrypt(encryptedData: string, keyString: string): Promise<string> {
+  const key = await importKey(keyString);
+  const combined = Uint8Array.from(atob(encryptedData), (c) => c.charCodeAt(0));
+  const iv = combined.slice(0, 12);
+  const data = combined.slice(12);
+  const decrypted = await crypto.subtle.decrypt(
+    { name: "AES-GCM", iv },
+    key,
+    data
+  );
+  return new TextDecoder().decode(decrypted);
+}
+
+export async function encryptFile(file: File, keyString: string): Promise<Blob> {
+  const key = await importKey(keyString);
+  const iv = crypto.getRandomValues(new Uint8Array(12));
+  const arrayBuffer = await file.arrayBuffer();
+  const encrypted = await crypto.subtle.encrypt(
+    { name: "AES-GCM", iv },
+    key,
+    arrayBuffer
+  );
+  const combined = new Uint8Array(iv.length + encrypted.byteLength);
+  combined.set(iv);
+  combined.set(new Uint8Array(encrypted), iv.length);
+  return new Blob([combined], { type: "application/octet-stream" });
+}
+
+export async function decryptFile(encryptedBlob: Blob, keyString: string): Promise<ArrayBuffer> {
+  const key = await importKey(keyString);
+  const combined = new Uint8Array(await encryptedBlob.arrayBuffer());
+  const iv = combined.slice(0, 12);
+  const data = combined.slice(12);
+  return crypto.subtle.decrypt({ name: "AES-GCM", iv }, key, data);
+}