Implement megaphone conditional standard_donate with local device createdAt

ts/textsecure/AccountManager.preload.ts

@@ -43,6 +43,8 @@ import {
   encryptDeviceName,
   generateRegistrationId,
   getRandomBytes,
+  decryptDeviceCreatedAt,
+  encryptDeviceCreatedAt,
 } from '../Crypto.node.js';
 import {
   generateKeyPair,
@@ -311,6 +313,58 @@ export default class AccountManager extends EventTarget {
     return name;
   }
 
+  // For testing
+  async _encryptDeviceCreatedAt(
+    createdAt: number,
+    deviceId: number
+  ): Promise<string> {
+    const ourAci = itemStorage.user.getCheckedAci();
+    const identityKey = signalProtocolStore.getIdentityKeyPair(ourAci);
+    const registrationId =
+      await signalProtocolStore.getLocalRegistrationId(ourAci);
+    strictAssert(identityKey, 'Missing identity key pair');
+    strictAssert(registrationId, 'Missing registrationId for our Aci');
+
+    const createdAtCiphertextBytes = encryptDeviceCreatedAt(
+      createdAt,
+      deviceId,
+      registrationId,
+      identityKey.publicKey
+    );
+
+    return Bytes.toBase64(createdAtCiphertextBytes);
+  }
+
+  async decryptDeviceCreatedAt(
+    createdAtCiphertextBase64: string,
+    deviceId: number
+  ): Promise<number> {
+    const ourAci = itemStorage.user.getCheckedAci();
+    const identityKey = signalProtocolStore.getIdentityKeyPair(ourAci);
+    if (!identityKey) {
+      throw new Error('decryptDeviceCreatedAt: No identity key pair!');
+    }
+
+    const registrationId =
+      await signalProtocolStore.getLocalRegistrationId(ourAci);
+    if (!registrationId) {
+      throw new Error('decryptDeviceCreatedAt: No registrationId for our Aci!');
+    }
+
+    const createdAtCiphertextBytes = Bytes.fromBase64(
+      createdAtCiphertextBase64
+    );
+
+    const createdAt = decryptDeviceCreatedAt(
+      createdAtCiphertextBytes,
+      deviceId,
+      registrationId,
+      identityKey.privateKey
+    );
+
+    return createdAt;
+  }
+
   async maybeUpdateDeviceName(): Promise<void> {
     const isNameEncrypted = itemStorage.user.getDeviceNameEncrypted();
     if (isNameEncrypted) {

ts/textsecure/WebAPI.preload.ts

@@ -967,7 +967,7 @@ const getDevicesResultZod = z.object({
       id: z.number(),
       name: z.string().nullish(), // primary devices may not have a name
       lastSeen: z.number().nullish(),
-      created: z.number().nullish(),
+      createdAtCiphertext: z.string(),
     })
   ),
 });

ts/textsecure/storage/User.dom.ts

@@ -152,6 +152,14 @@ export class User {
     return parseInt(value, 10);
   }
 
+  public getDeviceCreatedAt(): number | undefined {
+    return this.storage.get('deviceCreatedAt');
+  }
+
+  public async setDeviceCreatedAt(createdAt: number): Promise<void> {
+    return this.storage.put('deviceCreatedAt', createdAt);
+  }
+
   public getDeviceName(): string | undefined {
     return this.storage.get('device_name');
   }