ark/website/docs/learn/leaving.md

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4	Leaving the Ark

Overview

Alice wants to leave the Ark and get her funds back on-chain. It requires an on-chain transaction.

Cooperative exit

Timeline of events

1. Alice tells ASP she wants to trade VTXO for UTXO
2. ASP (with Alice) prepares next Pool transaction:
   • an additional output is added, locked by Alice
3. Alice creates a Forfeit transaction:
   • spends from VTXO (1) with Alice + ASP
   • adds connector output from Pool transaction (2) as input
   • signs it and send it to the ASP
4. ASP broadcasts Pool transaction
5. Alice has now a new UTXO
6. For at most 4 weeks, Alice will be able to double spend her VTXO, but if she does it, the ASP will have time (24 hours) to grab the funds from the VTXO to itself using the Forfeit transaction

Non-cooperative exit

If ASP is unresponsive, Alice can unilaterally exit revealing the branch of the Pool transaction that locks her funds.

Timeline of events

1. Assuming a VTXO tree with radix of 2 and 8 VTXOs:

flowchart TB
   tx1(TX 1) --> tx2(TX 2)
   tx1 --> tx3(TX 3)
   tx2 --> tx4(TX 4)
   tx2 --> tx5(TX 5)
   tx3 --> tx6(TX 6)
   tx3 --> tx7(TX 7)
   tx4 --> v1(VTXO 1)
   tx4 --> v2(VTXO 2)
   tx5 --> v3(VTXO 3)
   tx5 --> v4(VTXO 4)
   tx6 --> v5(VTXO 5)
   tx6 --> v6(VTXO 6)
   tx7 --> v7(VTXO 7)
   tx7 --> v8(VTXO 8)

2. Assuming VTXO 1 and 2 belong to Alice and Bob
3. Alice reveals the VTXO tree to spend the Shared Output.
4. Alice doesn't need to reveal the entire tree, just enough to validate it:

flowchart TB
   tx1(TX 1) --> tx2(TX 2)
   tx1 --> tx3(TX 3)
   tx2 --> tx4(TX 4)
   tx2 --> tx5(TX 5)
   tx4 --> v1(VTXO 1)
   tx4 --> v2(VTXO 2)

5. Alice will need to wait 24 hours to be able to spend her VTXO. This gives enough time to the ASP to prevent any double spend attempts by Alice.
6. Bob can also spend his VTXO in 24 hours, or do nothing and maintain his VTXO on the Ark.