Named for common derivations

[ChristopherA]

I think we need to support a larger list of common derivations here soon, in particular Singlesig Segwit, plus a custom option for any derivation.

Internally, when we see a derivation we know name of, there should be a field in view & print that says what kind of derivation is if we know it. Similarly, some also have alternative to our keyset format and use SLIP-10(?) prefixes like zpub.

[wolfmcnally]

Get me a list of the derivations you want to support for MVP, please.

[ChristopherA]

This is what I have so far. Looking for best way to describe other more rare uses: singlesig legacy bitcoin-core usage, singlesig electrum usage, BIP45, etc.

In general, we want to support the [fingerprint/m/path/to/key]xpub… form, but when we know that the SLIP-132 prefix (zpub, etc.) show that separately (i.e. use the xpub form in the keyset, but the slip-132 version without the [fingerprint/m/path/to/key] prefix is also show. If there is no SLIP-132 version, only keyset version xpub/xprv.

Name	BIP	Public Key	Private Key	Address Encoding	BIP32 Path
Singlesig Legacy Mainnet	BIP44	0x0488b21e - xpub	0x0488ade4 - xprv	P2PKH or P2SH	m/44'/0'
Singlesig Nested Segwit Mainet	BIP49	0x049d7cb2 - ypub	0x049d7878 - yprv	P2WPKH in P2SH	m/49'/0'
Singlesig Native Segwit	84	0x04b24746 - zpub	0x04b2430c - zprv	P2WPKH	m/84'/0'
Singlesig Legacy Testnet	BIP44	0x043587cf - tpub	0x04358394 - tprv	P2PKH or P2SH	m/44'/1'
Singlesig Nested Singlesig Testnet	BIP49	0x044a5262 - upub	0x044a4e28 - uprv	P2WPKH in P2SH	m/49'/1'
Singlesig Native Segwit Testnet	BIP84	0x045f1cf6 - vpub	0x045f18bc - vprv	P2WPKH	m/84'/1'

There also is no official BIP48, but this is what we know:

Name	BIP32 Path
Multisig Nested Segwit Mainnet	m/48'/0'/0'/1'
Multisig Native Segwit Mainet	m/48'/0'/0'/2'
Multisig Legacy Mainnet	m/48'/0'/0'/3'

I've heard that there is a use for m/48'/0'/0'/0' maybe for bitcoin core multisig, but I'm confused.

@Fonta1n3 — any thoughts of important other paths? Or better names for the list of common derivations?

[wolfmcnally]

This is all good information, but I think we need to reduce it to a specific feature description, i.e.: exactly which of these derivations do we want to support for MVP (or do we definitely support all of them), which are the most common and therefore need to be most-easily accessible, and what information do we need to provide users so they know what to pick for their application? How do we keep users from choosing the wrong one? I'm not asking for UX design, more a series of most-common use-cases and constraints.

[ChristopherA]

This is related to #134.

@shannona Can you confirm that we are using the right names for the common derivations in all the right places? Including places like (i) notes? Document in the repo which we have chosen to support as "named", and close this and #134 as appropriate.

[shannona]

There aren't a lot of places where we talk about actual derivations, but I've filed #150 to suggest the "What is Key Derivation?" text talk about an actual in-use derivation. I think that's it for the actual app.

[shannona]

Added some docs here: https://github.com/BlockchainCommons/crypto-commons/blob/master/Docs/key-derivations.md