Implement E2EE and message content moderation

apps/supabase/functions/_shared/encryption.ts

@@ -0,0 +1,38 @@
+import { decode, encode } from "https://deno.land/std@0.208.0/encoding/base64.ts";
+
+export interface KeysMetadata {
+  sender_wrapped_key: string;
+  recipient_wrapped_key?: string;
+  admin_wrapped_key: string;
+  admin_key_id: string;
+  algorithm: string;
+  key_wrap_algorithm: string;
+  pending_recipient?: boolean;
+}
+
+export async function unwrapWithAdminKey(
+  wrappedKeyBase64: string,
+  adminPrivateKeyJwk: JsonWebKey
+): Promise<ArrayBuffer> {
+  const privateKey = await crypto.subtle.importKey(
+    "jwk",
+    adminPrivateKeyJwk,
+    { name: "RSA-OAEP", hash: "SHA-256" },
+    false,
+    ["decrypt"]
+  );
+
+  return await crypto.subtle.decrypt(
+    { name: "RSA-OAEP" },
+    privateKey,
+    base64ToUint8Array(wrappedKeyBase64)
+  );
+}
+
+export function base64ToUint8Array(base64: string): Uint8Array {
+  return decode(base64);
+}
+
+export function arrayBufferToBase64(buffer: ArrayBuffer): string {
+  return encode(buffer);
+}