Transaction Memo

The transaction-level memo field is optional, and will be present if and only if the transaction has outputs. A consensus rule will reject transactions with memos that have no outputs, and transactions that have outputs but lack a memo.

Memo Plaintext

The plaintext of the memo contains:

• a return address (80 bytes for Penumbra addresses)
• a text string that is 432 bytes in length

Privacy

The transaction-level encrypted memo is visible only to the sender and receiver(s) of the transaction.

Each memo is encrypted using the Memo Key, a symmetric ChaCha20-Poly1305 key generated randomly as described here. The Memo Key is then encrypted using data from each output following this section. This Wrapped Memo Key is then added to each individual Output.