Secret or private keys are crucial to your operations on the Free TON blockchain.
They are used to sign messages and transactions that interact with smart contracts in Free TON.
These private keys protect all of your funds in the Free TON blockchain. Generally, you won’t need to know your private key, or enter in anywhere, while working with your account in Surf, as it is calculated automatically based on your seed phrase.
It can, however be viewed under Settings → Safety protection → Address and keys → Show private key.
Your private key should be treated with the same precautions as your seed phrase. Never share it with any person or application you do not trust with full access to your funds.
To learn more about Free TON cryptography from a developer viewpoint, refer to TON Labs SDK documentation.
More information about security in Surf you can find at https://medium.com/freeton/how-to-keep-my-cryptocurrency-safe-in-surf-a5d5c202b38d