A reproducible tree of keys
BIP-32 specifies hierarchical deterministic key derivation: a seed produces a master extended key, and indexed derivation produces descendants in a tree. An extended key includes a chain code alongside key material. This structure lets a wallet generate many addresses without requiring a new independent seed backup for each one. The hierarchy also permits controlled sharing of subtrees, which is useful when separating accounts, receiving addresses, or organizational responsibilities while retaining a coherent recovery scheme.
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Watching without holding spending keys
A service can receive an extended public key for a suitable non-hardened branch and derive receiving addresses without receiving the corresponding private keys. For example, a merchant's website can issue a fresh payment address for each order while signing authority remains elsewhere. This does not make the extended public key harmless: it can expose an entire branch's transaction history. Share only the branch needed for the task, and confirm how that branch relates to the wallet's recovery structure.
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Hardened derivation and recovery details
Hardened derivation prevents deriving the corresponding child branch from an extended public key alone. BIP-32 also explains an important hazard: combining a parent extended public key with a related non-hardened child private key can compromise the parent's private derivation capability. This is why extended-key handling deserves more care than sharing a single receiving address. BIP-32 does not itself specify a mnemonic word backup or every application's path convention. BIP-39 and BIP-44 address different layers, and restoring a wallet requires those layers to line up correctly.
The source notesEvidence & further reading3 sources
- BIP-32: Hierarchical deterministic wallets Bitcoin BIPs contributors · Primary source · accessed 2026-09-22
- BIP-39: Mnemonic code for generating deterministic keys Bitcoin BIPs contributors · Primary source · accessed 2026-09-22
- BIP-44: Multi-account hierarchy for deterministic wallets Bitcoin BIPs contributors · Primary source · accessed 2026-09-22