There are enough offerings on the market for cryptocurrency custody services. To protect keys, besides multi-signature technology, the use of secure computation protocols is gaining popularity.

Multi-signature - is a form of digital signature that requires multiple secret keys to authorize a transaction or signing of something. In the case of crypto-assets, multi-signature is used to sign transactions with multiple private keys, meaning the funds are stored using an address with multiple signatures, and access to them is granted with two or more keys owned by separate entities.

Secure computation protocol - is a cryptographic method that allows distributing one key among multiple organizations or individuals. It enables two or more parties to perform computations on their inputs while keeping those inputs private from each other. Thus, the key is never fully assembled in one place or stored entirely on one device. Mathematical operations are performed to reconstruct the full digital signature from a quorum of participants. As a result, the computed signature becomes identical to a unified signature.

Copper.co offers custody services for storing cryptocurrencies and digital assets. They utilize secure computation protocols to ensure the security of storing cryptocurrency keys.

Copper.co also employs multi-signature technology to secure transactions. Each transaction is signed by multiple participants using their private keys. This enhances security, as a malicious actor would need to access multiple keys to conduct an unauthorized transaction.

Additionally, Copper.co employs hardware storage for cryptocurrency, further enhancing security. The company also offers risk management and customer support services.

Finoa - is a custodian specializing in storing digital assets for institutional clients such as hedge funds, family offices, venture capitals, and others. They offer various security measures to protect their clients' digital assets. One of the key elements of their storage technology is multi-signature.

Finoa uses multi-signature to protect its clients' digital assets, allowing transactions only if approved by multiple authorized individuals. This prevents potential errors and abuses by a single individual.

Additionally, Finoa uses various key storage methods, including hardware security module (HSM), distributed storage across multiple devices, and key encryption.

Finoa also offers cybersecurity services such as continuous monitoring and intrusion detection to protect its clients' digital assets.

Metaco - is a cryptocurrency platform that provides institutional clients with solutions for secure storage and management of digital assets. One of their key products is the Silo custody solution, which ensures secure storage of cryptocurrencies and digital assets using multi-signature.

Silo uses multi-signature with multiple signatories, meaning that multiple agreed-upon signatures are required to conduct a transaction. Each key is stored in different locations, and access to the assets can only be obtained if all keys are together.

Additionally, Silo also offers secure digital asset exchange, allowing clients to manage their assets in a more secure and transparent environment. The solution also includes audit, monitoring, and risk management mechanisms to ensure maximum security of client assets.