Clear DefinitionsBrain Wallet
1 min read
Pronunciation
[brayn woll-it]
Analogy
A brain wallet is like memorizing the combination to a safe instead of carrying a key.
Definition
A wallet where the private key is derived from a memorized passphrase, without storing any seed or key material physically.
Key Points Intro
Brain wallets rely on human memory for key security and:
Key Points
Passphrase seed: Derives key via hashing (e.g., SHA256).
No storage: Nothing to steal except via memory compromise.
Vulnerability: Low‑entropy phrases are brute‑forced.
Mnemonic alternatives: BIP‑39 offers structured entropy.
Example
User chooses a long sentence, hashes it with SHA256 to produce a Bitcoin private key, and recreates wallet by re‑entering sentence.
Technical Deep Dive
Passphrase P processed through PBKDF2 or SHA256 to produce 256‑bit private key. Address = RIPEMD160(SHA256(pubkey)). Without salt or stretching, vulnerable to dictionary attacks.
Security Warning
Human‑memorable phrases lack entropy; brain wallets are highly susceptible to cracking—avoid in favor of BIP‑39.
Caveat
Risk of loss if passphrase forgotten; risk of theft if passphrase guessed.
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