feat: auto-captions

apps/web/src/lib/zk-encryption.ts

@@ -0,0 +1,71 @@
+/**
+ * True zero-knowledge encryption utilities
+ * Keys are generated randomly in the browser and never derived from server secrets
+ */
+
+export interface ZeroKnowledgeEncryptionResult {
+  encryptedData: ArrayBuffer;
+  key: ArrayBuffer;
+  iv: ArrayBuffer;
+}
+
+/**
+ * Encrypt data with a randomly generated key (true zero-knowledge)
+ */
+export async function encryptWithRandomKey(
+  data: ArrayBuffer
+): Promise<ZeroKnowledgeEncryptionResult> {
+  // Generate a truly random 256-bit key
+  const key = crypto.getRandomValues(new Uint8Array(32));
+
+  // Generate random IV
+  const iv = crypto.getRandomValues(new Uint8Array(12));
+
+  // Import the key for encryption
+  const cryptoKey = await crypto.subtle.importKey(
+    "raw",
+    key,
+    { name: " " },
+    false,
+    ["encrypt"]
+  );
+
+  // Encrypt the data
+  const encryptedResult = await crypto.subtle.encrypt(
+    { name: "AES-GCM", iv },
+    cryptoKey,
+    data
+  );
+
+  // For AES-GCM, we need to append the authentication tag
+  // The encrypted result contains both ciphertext and tag
+  return {
+    encryptedData: encryptedResult,
+    key: key.buffer,
+    iv: iv.buffer,
+  };
+}
+
+/**
+ * Convert ArrayBuffer to base64 string for transmission
+ */
+export function arrayBufferToBase64(buffer: ArrayBuffer): string {
+  const bytes = new Uint8Array(buffer);
+  let binary = "";
+  for (let i = 0; i < bytes.byteLength; i++) {
+    binary += String.fromCharCode(bytes[i]);
+  }
+  return btoa(binary);
+}
+
+/**
+ * Convert base64 string back to ArrayBuffer
+ */
+export function base64ToArrayBuffer(base64: string): ArrayBuffer {
+  const binary = atob(base64);
+  const bytes = new Uint8Array(binary.length);
+  for (let i = 0; i < binary.length; i++) {
+    bytes[i] = binary.charCodeAt(i);
+  }
+  return bytes.buffer;
+}