This BIP defines the derivation scheme for HD wallets using the P2WPKH ([[bip-0173.mediawiki|BIP 173]]) serialization format for segregated witness transactions.
==Motivation==
With the usage of P2WPKH transactions it is necessary to have a common derivation scheme.
It allows the user to use different HD wallets with the same masterseed and/or a single account seamlessly.
Thus the user needs to create dedicated segregated witness accounts, which ensures that only wallets compatible with this BIP will detect the accounts and handle them appropriately.
===Considerations===
We use the same rationale as described in Considerations section of [[bip-0049.mediawiki|BIP 49]].
==Specifications==
This BIP defines the two needed steps to derive multiple deterministic addresses based on a [[bip-0032.mediawiki|BIP 32]] root account.
===Public key derivation===
To derive a public key from the root account, this BIP uses the same account-structure as defined in [[bip-0044.mediawiki|BIP 44]] and [[bip-0049.mediawiki|BIP 49]], but only uses a different purpose value to indicate the different transaction serialization method.
For the <code>purpose</code>-path level it uses <code>84'</code>. The rest of the levels are used as defined in BIP44 or BIP49.
===Address derivation===
To derive the P2WPKH address from the above calculated public key, we use the encapsulation defined in [[bip-0141.mediawiki#p2wpkh|BIP 141]]:
witness: <signature> <pubkey>
scriptSig: (empty)
scriptPubKey: 0 <20-byte-key-hash>
(0x0014{20-byte-key-hash})
==Backwards Compatibility==
This BIP is not backwards compatible by design as described under [#considerations]. An incompatible wallet will not discover accounts at all and the user will notice that something is wrong.
