The Financial Information exchanged between an FIP and an FIU is encrypted using a protocol called “Diffie-Hellman Key Exchange.” This protocol allows two parties (i.e., the FIP and the FIU) with no prior knowledge of each other to establish a shared secret key jointly.
The FIP uses This shared secret key to encrypt the financial information it sends and the FIU to decrypt it once received. The key exchange protocol guarantees that no other party, including the AA, can get access to this shared secret key.
Please see thisto use an open-source implementation of this protocol that aligns with the AA specifications.
Data is end-to-end encrypted. The library is publicly available here. The signature generation and validation library can be found here