taler-typescript-core

commit 4002f124f2bfe26e5084012ed6d1cda56ddee37a
parent 9835654765454e1cdf3adb311d4c1ff878a8f21b
Author: Martin Schanzenbach <schanzen@gnunet.org>
Date:   Fri,  7 Nov 2025 21:23:39 +0100

minor refactoring

Diffstat:
M
packages/taler-wallet-core/src/mailbox.ts
 | 
79
+++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------------

1 file changed, 53 insertions(+), 26 deletions(-)
diff --git a/packages/taler-wallet-core/src/mailbox.ts b/packages/taler-wallet-core/src/mailbox.ts
@@ -225,6 +225,27 @@ export async function initMailbox(
   return mailboxConf;
 }
 
+function decryptTalerUriMessage(
+  sk: Uint8Array,
+  msg: Uint8Array,
+) : string | undefined {
+  const header = new Uint8Array(msg.slice(0, 4));
+  const ct = new Uint8Array(msg.slice(4));
+  const uri = hpkeOpenOneshot(sk,
+                              stringToBytes("mailbox-message"),
+                              header, // AAD
+                              ct);
+  if (!uri) {
+    return undefined;
+  }
+  // Find start of padding
+  const padIdx = uri.indexOf(0x00);
+  if (-1 === padIdx) {
+    return  new TextDecoder().decode(uri);
+  }
+  return new TextDecoder().decode(uri.slice(0, padIdx))
+}
+
 /**
  * Refresh mailbox through HTTP
  */
@@ -266,21 +287,16 @@ export async function refreshMailbox(
           const offset = i * message_size;
           const msg: Uint8Array = messages.slice(offset,
                                                  offset + message_size);
-          const header = new Uint8Array(msg.slice(0, 4));
-          const ct = new Uint8Array(msg.slice(4));
-          const uri = hpkeOpenOneshot(hpkeSk,
-                                      stringToBytes("mailbox-message"),
-                                      header, // AAD
-                                      ct);
+          const uri = decryptTalerUriMessage(hpkeSk,
+                                             msg);
           if (!uri) {
             logger.warn(`unable to decrypt message number ${i}`);
-            continue; // FIXME log
+            continue;
           }
           // Find start of padding
-          const padIdx = uri.indexOf(0x00);
           const newMessage = {
             originMailboxBaseUrl: mailboxConf.mailboxBaseUrl,
-            talerUri: new TextDecoder().decode(uri.slice(0, padIdx)),
+            talerUri: uri,
             downloadedAt: now,
           };
           records.push(newMessage);
@@ -318,16 +334,38 @@ export async function refreshMailbox(
   }
 }
 
+function encryptTalerUriMessage(
+  encryptionKey: Uint8Array,
+  talerUri: string,
+  paddedMessageSize: number
+) : Uint8Array {
+  const headerBuf = new ArrayBuffer(4);
+  // Padding must not include HPKE tag and encapsulation overhead
+  // FIXME CRYPTO-AGILITY size of tag and encapsulation depends on used algos
+  // DHKEM X25519: Encapsuation 32 bytes, Poly1305 tag 16 bytes
+  const paddingLength = paddedMessageSize - 4 - talerUri.length - 16 - 32;
+  const v = new DataView(headerBuf);
+  v.setUint32(0, 0); // FIXME message type, derive number from crypto!
+  const header = new Uint8Array(headerBuf);
+  const padding = new Uint8Array(paddingLength).fill(0);
+  const msg = new Uint8Array([...stringToBytes(talerUri), ...padding]);
+  const encryptedMessage = hpkeSealOneshot(encryptionKey,
+                                           stringToBytes("mailbox-message"),
+                                           header,
+                                           msg);
+  return new Uint8Array([...header, ...encryptedMessage])
+}
+
 export async function sendTalerUriMessage(
   wex: WalletExecutionContext,
   req: SendTalerUriMailboxMessageRequest) : Promise<EmptyObject> {
   const mailboxClient = new TalerMailboxInstanceHttpClient(req.contact.mailboxBaseUri, wex.http);
   // Get message size
-  var message_size;
+  var paddedMessageSize;
   const resConf = await mailboxClient.getConfig();
   switch (resConf.case) {
     case "ok":
-      message_size = resConf.body.message_body_bytes;
+      paddedMessageSize = resConf.body.message_body_bytes;
       break;
     default:
       return {};
@@ -341,23 +379,12 @@ export async function sendTalerUriMessage(
     default:
       throw Error("unable to get mailbox keys");
   }
-  const headerBuf = new ArrayBuffer(4);
-  // Padding must not include HPKE tag and encapsulation overhead
-  // FIXME CRYPTO-AGILITY size of tag and encapsulation depends on used algos
-  // DHKEM X25519: Encapsuation 32 bytes, Poly1305 tag 16 bytes
-  const paddingLength = message_size - 4 - req.talerUri.length - 16 - 32;
-  const v = new DataView(headerBuf);
-  v.setUint32(0, 0); // FIXME message type, derive number from URI type!
-  const header = new Uint8Array(headerBuf);
-  const padding = new Uint8Array(paddingLength).fill(0);
-  const msg = new Uint8Array([...stringToBytes(req.talerUri), ...padding]);
-  const encryptedMessage = hpkeSealOneshot(decodeCrock(keys.encryptionKey),
-                                           stringToBytes("mailbox-message"),
-                                           header,
-                                           msg);
+  const encryptedMessage = encryptTalerUriMessage(decodeCrock(keys.encryptionKey),
+                                                  req.talerUri,
+                                                  paddedMessageSize);
   const resSend = await mailboxClient.sendMessage({
     h_address: req.contact.mailboxAddress,
-    body: new Uint8Array([...header, ...encryptedMessage]),
+    body: encryptedMessage,
   });
   switch (resSend.case) {
     case "ok":