Brain Wallet

Brain Wallet

Warning: always unsafe for real money

Brain wallets are always unsafe for real money. Attackers precompute hashes of billions of phrases: quotes, lyrics, passwords, Bible verses, Wikipedia sentences. Funds on brain wallets are routinely stolen within hours. Even a strong passphrase has far less entropy than 12 random BIP39 words. Use the Derive Keys tab for real wallets. This tab exists only to demonstrate cryptographic concepts. See index.html:481-485.

Flow: SHA-256 to 24 words

1. The source passphrase is hashed with SHA-256 to produce 32 bytes of entropy. See src/brain-wallet-service.js:43-44.
2. Those bytes become a 24-word BIP39 mnemonic via entropyToMnemonic. See src/brain-wallet-service.js:45.
3. An optional BIP39 passphrase (the 25th word) can be applied to the derived mnemonic. See index.html:505-508.
4. Account and address index inputs shape the fixed paths. See index.html:510-519.

SHA-256 always emits 256 bits, but hashing cannot create randomness that was not in the input. See index.html:498-501.

Fixed 5 paths

These are never changed by the custom override. See src/brain-wallet-service.js:48-52.

• Ethereum / EVM: m/44'/60'/account'/0/index
• Bitcoin Legacy: m/44'/0'/account'/0/index
• Bitcoin Native SegWit: m/84'/0'/account'/0/index
• Tron: m/44'/195'/account'/0/index
• Solana: m/44'/501'/account'/index'

Optional custom path override

The brainCustomPath input accepts one extra path for comparison. Empty means no override. The brainSyncPathBtn button fills it from the account and index inputs. The 5 fixed paths above are always derived unchanged. See index.html:521-528 and src/brain-wallet-service.js:91-94.

Auto-harden for 501, 784, 637

Ed25519 coins auto-harden like the Derive tab does. If the custom path uses coin type 501 (Solana), 784 (Sui), or 637 (Aptos), every segment is hardened and the result notes the resolved path. See src/brain-wallet-service.js:101-107 and src/constants.js:20-21.

Where outputs show

Results render under brainOutput. See index.html:535-578.

• brainMnemonic: 24-word mnemonic.
• brainAddress and brainPrivateKey: Ethereum address and key, with QR at brainQrHost.
• brainBtcLeg, brainBtcSw, brainBtcWif: Legacy, Native SegWit, and WIF.
• brainTrx: Tron address.
• brainSol: Solana address, derived async via deriveBrainSolAddress. See src/brain-wallet-service.js:83-86.
• brainCustomWrap with brainCustomAddress and brainCustomPrivateKey: shown only when the override is used.

Frozen vectors

Pinned in test/vectors.js:258-271. They lock the demo, not endorse it.

• brain-xkcd: passphrase correct horse battery staple, expected Ethereum address.
• brain-xkcd-custom-evm: same passphrase at m/44'/60'/1'/0/5, expected address plus private key.
• brain-xkcd-custom-sol: same passphrase at m/44'/501'/0'/0/0, resolved to m/44'/501'/0'/0'/0'.

How to verify

npm test

The brain section of test/run-vectors.js:475-502 re-derives each vector through the shipped code and compares addresses, keys, and resolved paths.