Sending the decrypted bill of exchange to Mint for checking

[mtbitcr]

The first action the user takes is some sort of request to mint. In it the user should pass the bill of exchange to mint for checking. In this case we do not want to pass the key from the bill immediately. So our sequence of actions will be as follows:

• the user decrypts the bill of exchange with the key from the bill of exchange
• the user encrypts the bill with mint keys and sends this byte array to mint.
• mint decrypts the bill of exchange and views it in its eBill application (mint version)
  The bill of exchange can be sent either via Nostr (this is preferred) or via endpoint mint.