Are mnemonic seeds or hierarchical deterministic wallets standardized?

Question

Some wallets for Bitcoin and Ethereum will give you a list of about 15 words to write down instead of giving you a private key.

From what I understand, the list of words is derived from the key, and can be used to recreate it.

The question I have, is basically whether or not ALL (or virtually all) implementations of this system are compatible. Imagine I try to recover my wallet using the seed years later on a totally different wallet. Can I be confident it will work. Are all seed mnemonics using the exact same math, and will they likely continue with the same scheme (or a backwards compatible one) decades from now?

Answer 1

There are several bitcoin standards related to creating keys from mnemonic seeds.

BIP 39 for making mnemonics to create a seed: https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki

BIP 32 for deriving keys from that seed: https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki

However, not all clients use all these standards (eg Electrum's mnemonic implementation is different - I think it pre-dates the standard and the developers weren't really happy with the standard) and there's a little bit of room for different ways of implementing things even if you're trying to follow it; For example, a wallet is allowed to have different derivation paths for different "accounts", but it doesn't have to.

So no, you can't quite be confident your seed will still work as is on an arbitrary future wallet, although it might. But if there's a lot of money in there it should be possible to dig out the way the old wallet was doing the thing and re-implement enough of it to get your private keys out.

Answer 2

What interests me is, if for example the seeds of Coinomi (multi-coin) and MetaMask(ETH) are compatible, since they both use the BIP 44 standard. But that would mean metamask could support different altcoins aswell. Can anyone clear that up?

Someone on reddit explained the relevant Bitcoin improvement proposals (BIP) quite simply:

bip32 = hd wallets, what they are how they work

bip39 = specific type of mnemonic, and the process for turning it into a bip32 seed

bip44 = a specific format of a bip32 wallet

But yeah, I was asking something related but it seems not too many people know or wanna share their knowledge. (Using single addresses from HD wallet elsewhere)