Workflow

The diagram illustrates the process of creating and spending various Bitcoin outputs through different transactions as described in the following paragraphs.

There are four types of transactions in the Self Custody system:

• Mapping Credential Transaction

• Burning Credential Transaction

• Forced Withdrawal Transaction

• Escape Hatch Transaction

Mapping Credential Transaction

The mapper generates WBTC by creating a mapping transaction. This is a Bitcoin transaction where a certain amount of bitcoins to be minted is submitted to a mapping script approved by Bool Network. These scripts lock a selected number of BTC. The requirements for a valid mapping transaction are:

• It can contain an arbitrary number of inputs.

• It can contain any number of outputs. One of these outputs must be the taproot output submitted to the BTC mapping script recognized by Bool Network. Hereafter called the mapping output. The output must also contain an OP_RETURN with the information that needs to be map.

Burning Credential Transaction

When BTC mappers want to redeem their assets before the originally promised time lock expires, they use the burning credential transaction. The requirements for a valid burning credential transaction are:

• It can contain any number of inputs that point to the mapping output of the mapping credential transaction。

• It can contain at least two outputs, the first is the address of the BTC mapper. the second must also contain an OP_RETURN with burn information. If the selected input amount has excess BTC assets after deducting the burn amount, a taproot output of the BTC mapping script identified by Bool Network is added.

Forced Withdrawal Transaction

When the BTC mapper does not burn the assets before the time lock expires, due to disagreements over the content of the burning credential transaction, the committee will use a forced withdrawal transaction to transfer the assets out of the mapping script. The requirements for a valid forced withdrawal transaction are:

• It can contain any number of inputs that point to the mapping output of the mapping transaction.

• It contains only one output, which must be the taproot output submitted to the mapping script recognized by Bool Network. Unlike mapping credential transaction, the output of a forced withdrawal transaction does not require an additional OP_RETURN.

Escape Hatch Transaction