Your private keys are your most valuable possessions in the blockchain space. Private keys are what hold information as to how much cryptocurrency you have and what you can spend. If you lose your private keys or they are compromised, you will never be able to get your currencies back. The most important part of working with cryptocurrencies and blockchains is the secure management of your private keys.
There are 4 options for how Tatum handles private keys to blockchain addresses:
sending private keys/mnemonic seeds to Tatum's API directly - This is not recommended in the production environment, and it should be used in a testnet only. Tatum never stores any private keys or mnemonic seeds.
using Tatum KMS, an external tool to securely generate and store private keys and use them to sign transactions locally. This is the safest and recommended way of working with private keys. Tatum KMS should be installed in the Deny-From-All environment to meet the highest security standards. It is possible to store private keys locally or using AWS HSM or Azure HSM. Tatum KMS only communicates with Tatum's API to fetch the list of the pending transactions to sign. After successfully signing and broadcasting transactions to the blockchain, it marks the pending transaction as complete and adds the final broadcasted transaction ID. It supports the 4 eye control mechanism, where pending transactions are controlled in Tatum and the customer system.