Antminer X9
Monero ASIC Miner
1000KH
HASHRATE
2.47W/KH
EFFICIENCY
2470W
POWER
£861.31
EST. MONTHLY
205
DAYS
EST. ROI
This guide explains BIP 49 nested SegWit in plain English. It covers the problem behind the BIP, why it matters and whether the proposal is part of Bitcoin today.
TL;DR
- What it is: BIP 49 defines a dedicated hierarchical-deterministic account branch for pay-to-witness-public-key-hash nested inside pay-to-script-hash. It uses purpose 49 so incompatible wallets do not silently mix legacy and nested SegWit accounts.
- Why it matters: BIP 49 gives nested SegWit accounts a distinct, recoverable derivation namespace. Reliable recovery requires the path, script type, network and discovery range, not just a mnemonic or extended-key prefix.
- Current position: The specification is Deployed, but recovery still depends on seed format, derivation path, coin type, account discovery and extended-key version support.
BIP 49 nested SegWit in simple English
BIP 49 nested SegWit: The account convention follows m / 49 prime / coin type prime / account prime, then external or change branch and address index.
Simple example
A node operator is checking BIP 49 nested SegWit. Verify destination descriptors and hardware display before signing, and retain the old recovery record until final reconciliation.
Key terms in plain English
- BIP:
- Bitcoin Improvement Proposal: a document describing a proposed rule, standard or process. Its status must be checked separately.
- Taproot:
- A Bitcoin upgrade that added new signature and script options for spending outputs.
- Node:
- A computer running Bitcoin software that checks data and communicates with other peers.
Derivation path
The account convention follows m / 49 prime / coin type prime / account prime, then external or change branch and address index. Hardened boundaries protect higher-level derivation assumptions. A seed alone does not identify the path, network, account range or script type, so recovery documentation must preserve them.
Nested SegWit script
The public key hashes into a version-zero witness programme, which is wrapped as a P2SH redeem script for a familiar base58 address. Spending places the redeem programme in scriptSig and the signature and key in witness. It is not native SegWit and has different weight and address encoding.
Dedicated accounts
BIP 49 recommends a separate account so a wallet unaware of the scheme fails clearly rather than showing an incomplete balance. Mixing script types under one discovery branch can make restoration dependent on vendor heuristics. Preserve account numbers and used change ranges explicitly.
Extended-key versions
The BIP records alternate public and private extended-key version bytes commonly displayed as ypub and yprv on mainnet. These encodings signal intended script context but are not the underlying key material. Import support varies, and converting prefixes without checking derivation and network can produce plausible wrong addresses.
Discovery and gap limits
A recovering wallet derives external and internal branches until its gap policy finds no further use. Sparse indexes, multiple accounts and missed change can hide funds. Test recovery from the oldest backup against a fixture with deliberately distant receive and change indexes.
Migration choices
Funds can remain in nested SegWit or move to a supported native SegWit or Taproot wallet. Migration is an on-chain spend with fees, confirmation and change risk, not a prefix conversion. Verify destination descriptors and hardware display before signing, and retain the old recovery record until final reconciliation.
How specialists test it
Developers test the proposal with made-up data on an isolated test network. They check normal cases and deliberately invalid cases. Different implementations should reach the same result before anyone relies on the proposal.
Frequently asked questions
What is the main point of BIP 49 nested SegWit?
BIP 49 nested SegWit: The account convention follows m / 49 prime / coin type prime / account prime, then external or change branch and address index.
For BIP 49 nested SegWit, what should a beginner know about derivation path?
The account convention follows m / 49 prime / coin type prime / account prime, then external or change branch and address index.
For BIP 49 nested SegWit, what should a beginner know about nested SegWit script?
The public key hashes into a version-zero witness programme, which is wrapped as a P2SH redeem script for a familiar base58 address.
For BIP 49 nested SegWit, what should a beginner know about dedicated accounts?
BIP 49 recommends a separate account so a wallet unaware of the scheme fails clearly rather than showing an incomplete balance.
Conclusion
BIP 49 gives nested SegWit accounts a distinct, recoverable derivation namespace. Reliable recovery requires the path, script type, network and discovery range, not just a mnemonic or extended-key prefix.
Primary sources
Check the current specification status and the documentation for the exact implementation you operate before moving production funds or changing a mining node.
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