To secure CKB on MetaMask, you want to use Portal Wallet (ckb.pw).
Portal Wallet (ckb.pw) is web-based CKB wallet that ports your CKB address onto an Ethereum address. This Ethereum address is what the CKB blockchain uses to port onto MetaMask and other popular web-based wallets built on the EVM. This means that the Portal Wallet generates its own CKB address that points to the Ethereum address, and is independent of other CKB wallet addresses
To connect to MetaMask from another wallet, you must make transactions between the wallet's CKB address and the CKB address generated by Portal wallet. (Transaction fees for these transfers between addresses are negligible.)
Porting your CKB to MetaMask and other browser-based wallets through Portal Wallet is often a necessary step for participating in many DeFi services, such as staking and yield farming on YokaiSwap. Additionally, the Portal Wallet can be used to deposit into NervosDAO: https://dao.ckb.pw/
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