Cashbox is a patent-pending method developed by Custody Infrastructure that allows you to send pre-approved Cold Vault transactions from the MPC without accessing the Cold Vault itself at the time of the transactions (the Cold Vault is required to initially configure the cashboxes). When creating a Cashbox in the Cold Vault, a set of policies is defined, including:

These limits are enforced at the cryptographic level. This ensures that even if the MPC is somehow compromised, there is no way the funds can be diverted from their intended recipient.

Cashboxes can support BTC, BCH, and most EVMs and ERC-20s. However, Cashboxes do not support Layer 2 (L2) networks. This means that any ERC-20 tokens deployed on L2s are also unsupported.

The following EVMs (and ERC-20s on these EVMs) are explicitly not supported:

Cashbox policies are enforced at the cryptographic level. Even if a hacker gains access to the system, hacking the entire MPC, they are unable to send any money in the Cashbox to themselves. Assets can only be sent out from the Cashbox up to the predefined limit and to the preconfigured destinations. Even the fee limits are configured in advance and immutable.

Cashbox transactions are Cold Vault signed transactions. They are as secure as any other Cold Vault transactions. There is no way to re-allocate funds from a Cashbox to any destination besides those originally defined.

An MPC user with appropriate permissions can close an active Cashbox; on closing, all remaining funds in the Cashbox are automatically sent directly back to the Cold Vault. The funds never sit on any MPC address.

When creating a Cashbox you must set its number of parts. This directly impacts the amount of funds that can be sent in a transaction:

The total amount of funds in the Cashbox is divided into a "number of parts" . A number between 1 and 10 should be chosen for the number of parts.

The amount of money allocated to the Cashbox is divided by the number of parts to give the Cashbox's increment size. All transactions sent out from this Cashbox must be an integer multiple of the increment size.

To put it another way, all transactions sent from the Cashbox must contain a whole number of parts.

For example, if one sets 100 BTC in a Cashbox, and sets 10 parts, they will only be able to send transactions of sizes: 10BTC, 20BTC, 30BTC, ..., 100BTC (Including fee) from that Cashbox. All transactions must be whole increments of 10BTC.

Protected destination is a feature that is set per-destination during the creation of a Cashbox.

This feature forces the user to enter system-defined password(s) whenever they wish to create transactions to this destination. Without the proper password authentication, the MPC is unable to send assets out from the Cashbox to the predefined protected destination. If the MPC hot wallet address is added as a destination, it will automatically be configured as protected.

These passwords are used to authorize any transactions being sent to protected destinations.

Cashbox transaction password requirements vary depending on the currency being used. There are transactions that only require one password and transactions that may require more. As more passwords are required, more password entry fields are populated.