Generating Deterministic Polkadot Addresses

[farukterzioglu]

With my implementation, anyone can generate Polkadot addresses based on Bip32-Ed25519.

My implementation has the same results with test vectors here;
https://github.com/satoshilabs/slips/blob/master/slip-0010.md#test-vector-1-for-ed25519

I can also confirm that addresses I generated is same with generate from subkey with private key if I investigate it.

Results from my code;

Address: 5G6tXDeie2KaUgGrwkBfzApKSCm9sE5QvBm1bi1vmBZ4gcCN
Public key: b29b533725c02f6e69d8774c92d8a5a98506c2f09e13a1adbe4db367fbfa512a
Private key: 8bd78fe8b30abf91d3e9474c8927d9874fabc7e31ce2d866cf795378161f954a
Expanded private key: 8bd78fe8b30abf91d3e9474c8927d9874fabc7e31ce2d866cf795378161f954ab29b533725c02f6e69d8774c92d8a5a98506c2f09e13a1adbe4db367fbfa512a
Result from Subkey

subkey inspect 0x8bd78fe8b30abf91d3e9474c8927d9874fabc7e31ce2d866cf795378161f954a --scheme Ed25519
Secret Key URI 0x8bd78fe8b30abf91d3e9474c8927d9874fabc7e31ce2d866cf795378161f954a is account:
Secret seed: 0x8bd78fe8b30abf91d3e9474c8927d9874fabc7e31ce2d866cf795378161f954a
Public key (hex): 0xb29b533725c02f6e69d8774c92d8a5a98506c2f09e13a1adbe4db367fbfa512a
Account ID: 0xb29b533725c02f6e69d8774c92d8a5a98506c2f09e13a1adbe4db367fbfa512a
SS58 Address: 5G6tXDeie2KaUgGrwkBfzApKSCm9sE5QvBm1bi1vmBZ4gcCN
When I investigate the private key from my hd wallet implementation, Subkey prints the same address as I generated.

The problem here that, my implementation is not suitable with official hd wallet implementation which uses path like P//hard//soft (where P is mnemonic)
I rather use a path as m/44/354/0/0/0, to define 0. account's 0. deposit wallet.

The gotcha here is that, from same mnemonic I can't produce the same set of addresses with other available wallets.

[danforbes]

@farukterzioglu - I am not an expert in these issues, but I can provide two other suggestions for places to look for help:

1. make a post on Stack Overflow and tag it substrate
2. open an Issue on the Substrate subport repo: https://github.com/paritytech/subport/issues/new

[jacogr]

If you are using the standard mnemonic -> seed as per eg. ETH/BTC it won’t match.

Substrate goes from mnemonic-> entropy and then does pdkdf2 rounds (with the ///password and a known prefix) to get the private key (mini secret in Substrate terminology)

The outputs are vastly different between the 2 approaches so even something with no derivation will not match.

Trivia tidbits -

• Around poc-1 the first approach was still taken in Polkadot, it was changed in poc-2 for better use of the available material
• Ledger keys are derived like yours, so non-Substrate-matching, but obviously still works since the crypto is ed25519 and supported