BIP39.ai
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BIP39 Guides

Longer answers to common questions about seed phrases, checked against the BIP39 specification and test vectors.

  1. 12 vs 24 Word Seed Phrases

    A 12-word BIP39 phrase holds 128 bits of entropy and is already far beyond brute force. 24 words (256 bits) mainly help if part of your backup is ever exposed.

  2. Seed Phrase vs Private Key

    A seed phrase is a backup of the whole wallet: every private key is derived from it. A private key controls a single address. You can get keys from a phrase, but never the phrase from a key.