Electrum

Electrum’s focus is speed, with low resource usage and simplifying Bitcoin. Startup times are instant because it operates in conjunction with high-performance servers that handle the most complicated parts of the Bitcoin system.

Electrum client never sends private keys to the servers. In addition, it verifies the information reported by servers, using a technique called Simple Payment Verification.

The seed phrase created by Electrum has 132 bits of entropy. This means that it provides the same level of security as a Bitcoin private key (of length 256 bits). Indeed, an elliptic curve key of length n provides n/2 bits of security.

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