Flow

Estimated reading time: 2 minutes

Sections in this page

• High level flow
• Detailed flow
  • Display quote information to user
  • Swap transaction flow
  • Check swap status flow
  • More details
• High level architecture

High level flow

The Exchange Application is an application for Ledger’s devices (Nano S, Nano X and Nano S Plus) that has been developed specifically to manage and secure swap operations (crypto-to-crypto transfer).

The trade between the provider and the user is secured by going through Ledger Live back-end, front-end and the Exchange app installed on the Hardware Wallet. The provider signs the trade data, in order to let the Ledger’s device (Nano S, Nano X or Nano S Plus) display it to the user. Since the Ledger’s device (Nano S, Nano X or Nano S Plus) is the single source of truth, the user can trust and sign the transaction on the device, thus allowing the provider to complete the transaction. The provider is accredited by Ledger so that the Nano device can trust the provider data.

Detailed flow

Display quote information to user

Swap transaction flow

Check swap status flow

More details

More info about the important steps of the detailed diagram:

• Payload and Signature
  From the provider to Ledger Live. The payload is a protobuf message containing the trade data. It is generated by the Ledger Live backend and signed by the provider who sent it back to Ledger Live. More details in the Protobuf message (payload) section.
  

  payload = {
  payin_address,      // address (of provider)
  refund_address,     // address (of customer) 
  payout_address,     // address (of customer) 
  currency_from,      // currency name (to provider)
  currency_to,
  amount_to_provider, // amount (to provider)
  amount_to_wallet,   // amount (to customer)
  nonce,
  …
  }
  R, S = Sign(payload, priv_key)
  

• Validate
  Exchange app checks and validates payload (signature and content).
  

  Compare nonce in payload 
  Verify((R, S), payload, pub_key)
  

• Display
  Exchange app request approval to user by displaying swap summary on screen.
  

  Validate?
  Send in_currency in_amount
  Receive out_currency out_amount
  

High level architecture

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