Overview

For further explanation, we will use the following terms:

  • Participant - a user that wants to shuffle his UTXOs.
  • Input - a UTXO that the participant wants to shuffle, spent.
  • Output - an address that will receive a UTXO after shuffling.
  • Encrypted Outputs - a list of outputs encrypted by RSA secret key.
  • Service - a service that provides coordination logic for participants without any ability to reveal output addresses or steal UTXOs.
  • Room - a group of participants that are currently shuffling their UTXOs.

The shuffling process is done in the following steps:

  1. Participants Registration. Participants register in the service by providing their ownership proof of UTXOs that they want to spend.
  2. Shuffle start. Service waits for enough participants to register and then starts the shuffling process.
  3. Participants connection. Participants send their RSA public keys to the service to notify service that they are ready for shuffling.
  4. Keys distribution - service defines order of shuffling and sends RSA public keys that are required for participants to decrypt encrypted outputs.
  5. Shuffling.
    1. First participant encrypts his output with the RSA public keys of the next participants, in order, that each next participant will be able to decrypt its upper "layer" of encryption. Then, the participant sends encrypted output to the service.
    2. Next participant decrypts encrypted outputs of the previous participant and encrypts his output with RSA public keys of next participants and sends new encrypted outputs to the service.
    3. This process continues until the last participant will get a list of outputs without any encryption.
  6. Transaction distribution. After the last participant sends a fully decrypted outputs to the service, service forms a transaction, that each the participant should sign.
  7. Transaction signing. Each participant verifies a transaction, sees that has input and output are included, signs it, and sends signature to the service.
  8. Transaction sending. Service gathers all signatures and sends transaction to the network.