Cold refill wallet

Liminal Smart Refill:


Using the Liminal Smart Refill solution, exchanges and crypto platforms can create custom refill schedules. The Smart Refill Wallet automatically executes refills based on the pre-defined schedule to ensure uninterrupted operation.
With this solution, platforms can not only streamline their hot wallet refilling process but also save a considerable amount of time and resources that are otherwise dedicated to this purpose.

Key Configuration

Refill wallets are multisig wallets with flexible m/n wallet configurations. You can add members according to your needs and size of operations.

Key Providers

Solving the operational challenge to refill

Challenges of Manual Wallet Refill Process

  1. Time-Consuming Process
    Conducting manual wallet refills is a resource intensive task involving a series of complex steps. While these steps enforce safety and accountability, they can also cause unnecessary delays in refilling. Any such delay has the potential to disrupt services, causing inconvenience to the customers and impacting the platform’s reputation.

  2. Inefficient Use of Manpower
    Volatility of crypto assets makes it hard for exchanges and crypto platforms to predict customer demands. The team has to be available around the clock to fulfill any unforeseen demand at any time.

  3. Increased Chances of Mismanagement
    Mismanagement of wallet keys or funds due to human errors or omissions during the fund transfer process may seriously threaten the security of the funds and ultimately the platform.

Our solution - Smart refill wallets

The “Liminal Option” for Automated Wallet Refills
Liminal’s innovative solution automates the hot wallet refill process without compromising the security. Platforms implementing Liminal’s solution will be able to enjoy the benefits of automation while retaining complete control over the entire process.
By creating custom refill schedules, the operators will be able to affect automatic wallet refills in accordance to the predefined parameters. It will help the platforms streamline their hot wallet refill process in an efficient and economical way, with minimal resource allotment specifically for the purpose.

Liminal Smart Refill Process

To enable automated wallet refills, all transactions are partially signed in advance by authorized signatories. Based on the wallet configuration, the partially signed transactions will include m-1 signatures, with the Liminal system holding and operating one of the private keys as a final signing authority to successfully execute the transaction.
Each Smart Refill Wallet can interact with a single pre-approved hot wallet. With the refill policies defined in advance, the Smart Refill Wallet continuously monitors the status of the connected hot wallet and initiates refill whenever the liquidity falls below the predefined threshold. The refill is executed by signing off partially signed transactions using Liminal key once the hot wallet conditions satisfy the pre-defined parameters. Further, the Smart Refill wallet also offers a “Push” feature that allows the platform’s team to manually override automation to conduct forced refills ahead of schedule in extraordinary circumstances.

Advantages of Liminal Smart Refill

Predictable Refills, Uninterrupted Service
Scheduled refilling and refill ceremonies introduces predictability to operations while ensuring uninterrupted periodic liquidity provisioning to the hot wallets for seamless service delivery to customers.

Guaranteed On-time Refills
The Smart Refill Wallet provides transaction confirmation guarantees by using intelligent algorithms that automatically set optimal gas fees to enable swift transaction confirmations. Any transaction failures are also addressed through follow-up attempts until successful.

Manual Override
The availability of push refill and refill schedule modification options on Smart Refill Wallets allow platforms to maintain control over the automated refill operations through manual interventions at all times.

Constant Updates
Finally, the relevant heads of the organization and authorized parties on Liminal’s Smart Refill solution are always kept updated about the refill status through email and SMS channels.

Implementing the Liminal Smart Refill Solution

To use the Smart Refill Solution, platforms should first set up the solution by declaring the refill parameters.

The necessary parameters for scheduling Smart Refills include:

  1. Amount for each refill: The platform must define the total amount of crypto assets to be transferred during each refill. The Liminal smart wallet solution will use this input to create refill batches, with the exact amount of crypto assets to be transferred from the Smart Refill Wallet to the specified hot wallet
  2. Occurrence: The occurrence specified by the customer decides the number of transactions to be included in each batch by Liminal for pre-approval in what is known as the refill ceremony. The resulting pre-signed transactions will be later signed by Liminal Signer, completing the signature requirements to initiate transfer of funds from the Smart Refill Wallet to the associated hot wallet whenever the need arises.
  3. Cooldown: The Cooldown period indicates the minimum interval between two consecutive hot wallet refill actions. Depending on the specified cooldown period, the Smart Refill Wallet will ensure that subsequent refills are executed only after the stipulated duration is completed. In an event where a refill must be performed before the cooldown period has elapsed, the platform can manually override the conditions to execute a one-time refill action, following which the automated process will revert to the predefined intervals as stated in the parameters during setup
  4. Whitelist: For security purposes, each Smart Refill Wallet can be associated with only one hot wallet, The respective hot wallet address must be whitelisted on the Liminal Smart Refill system to be able to receive funds from the designated Smart Refill Wallet
  5. Trigger Amount: Platforms can set a trigger amount to activate the Smart Refill system to initiate the refill process. The Smart Refill system will send a predefined refill amount from the Smart Refill Wallet to the hot wallet whenever the balance reaches or falls below the trigger amount

Once all the parameters are defined, the platform is ready for its first Refill Ceremony to kickstart automated wallet refills.

Refill Ceremony

The Liminal Smart Refill solution requires the platform to sign multiple transactions in batches. The number of transactions in each batch will be decided as part of the “Occurrence” during the setup process, based on which the Smart Wallet Refill solution creates refill batches with the requisite number of transactions, to be signed in advance by the concerned team using their respective hardware wallets only.
Based on the requested schedule, the Smart Wallet Refill solution creates refill batches containing the relevant number of transactions. These batch transactions need to be signed in advance by the concerned team in charge of the hot wallet refill process using their respective hardware wallets only.
Once the necessary signatures from all the authorized members are in place, the Smart Refill Wallet will be able to perform automatic hot wallet refills. This entire process of periodically requesting signatures to create refill batches is automated and known as Refill Ceremony.
For the automated refill process to work without interruption, the Smart Refill Wallet should have the necessary funds available at the time of scheduled refill and not during refill ceremony.

Technincal implmentation

Hot Wallet Monitoring

The Smart Refill Wallet continuously monitors the connected hot wallet’s balance. Once the balance goes below the defined trigger amount threshold, it will initiate a refill transaction.

Nonce managment

Transactions on EVM and account-based chains have to happen in a sequence . The nonce management watcher keeps an eye on the current nonce of Smart Refill Wallets.
While creating a batch, future nonce are applied to a transaction based on its position in the batch
In an event of manual transaction from the refill wallet, a transaction at the same nonce in the batch is invalidated to decrease the number of available partially signed transactions in the batch by one.

Result: Operational manual refills reduced by 80 - 90%

Our customers implementing Liminal Smart Refill Wallets in their operations were able to optimize their manual refills by over 80%, resulting in higher customer satisfaction among exchange users.
How ZebPay automated 90% of their refill infrastructure

Some key points (as of 15-Aug-2022)

In total, we have processed ~500 M of refill transactions and saved ~240 hours in refill effort

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