Support for NUT-19 mint and wallet side #670

lollerfirst · 2024-11-15T08:56:59Z

Adding support for NUT-19.
Main changes:

Common:

MintQuote has two more optional fields named privkey and pubkey
nut19.py contains construct_message, sign_mint_quote and verify_mint_quote
PostMintQuoteRequest has one more optional field named pubkey
PostMintRequest has one more optional field named pubkey

Mint:

If a PostMintQuoteRequest contains a pubkey, save the public key together with the quote and
require a BIP340 signature from said public key on the mint request's quote id and blind messages.
If a PostMintQuoteRequest does not contain a pubkey while Mint is configured to require it, reject the request.
Signal support for NUT-19 and requirement for NUT-19

Wallet:

When requesting a quote -if the Mint supports NUT19- generate an ephemeral keypair and include pubkey in the PostMintRequest.
Include privkey in the quote when saving it to DB.
When minting always pull the quote from DB and if the quote has a non-null key, sign the quote id and the blinded message with key

…nto nut-19

cashu/core/base.py

cashu/mint/crud.py

cashu/mint/ledger.py

callebtc · 2024-11-15T14:01:00Z

cashu/mint/ledger.py

@@ -518,13 +520,15 @@ async def mint(
        *,
        outputs: List[BlindedMessage],
        quote_id: str,
+        witness: Optional[str] = None,
    ) -> List[BlindedSignature]:
        """Mints new coins if quote with `quote_id` was paid. Ingest blind messages `outputs` and returns blind signatures `promises`.

        Args:
            outputs (List[BlindedMessage]): Outputs (blinded messages) to sign.
            quote_id (str): Mint quote id.
            keyset (Optional[MintKeyset], optional): Keyset to use. If not provided, uses active keyset. Defaults to None.


Suggested change

keyset (Optional[MintKeyset], optional): Keyset to use. If not provided, uses active keyset. Defaults to None.

outdated

cashu/mint/ledger.py

callebtc · 2024-11-15T14:01:23Z

cashu/mint/migrations.py

+        await conn.execute(
+            f"""
+                ALTER TABLE {db.table_with_schema("mint_quotes")}
+                ADD COLUMN key TEXT DEFAULT NULL


Same here (key -> pubkey)

callebtc · 2024-11-15T14:03:28Z

cashu/core/crypto/nut19.py

+
+
+def construct_message(quote_id: str, outputs: List[BlindedMessage]) -> bytes:
+    serialized_outputs = bytes.fromhex("".join([o.B_ for o in outputs]))


Suggested change

serialized_outputs = bytes.fromhex("".join([o.B_ for o in outputs]))

serialized_outputs = bytes.fromhex("".join([o.B_ for o in outputs]))

This should be utf-8 encoded?

cashu/wallet/cli/cli.py

cashu/wallet/wallet.py

callebtc · 2024-11-15T14:07:31Z

Nice work. One issue here is that key is confusing and it seems like you're storing pubkey as well as privatekey in the same field, depending on whether it is the mint or the wallet.

callebtc · 2024-11-15T14:08:50Z

I think we should move the file core/crypto/nut19.py to a new directory core/nuts and clean up nut-specific stuff in the future to this path.

lollerfirst · 2024-11-15T14:11:33Z

Nice work. One issue here is that key is confusing and it seems like you're storing pubkey as well as privatekey in the same field, depending on whether it is the mint or the wallet.

yea that was the idea. The alternative is keeping the private key separate but still storing it together with the quote in the DB. And then when we request the quote from DB also return the separate private key.

callebtc · 2024-11-15T14:09:37Z

cashu/wallet/wallet_deprecated.py

@@ -261,6 +261,7 @@ async def request_mint_deprecated(self, amount) -> PostMintQuoteResponse:
            paid=False,
            state=MintQuoteState.unpaid.value,
            expiry=decoded_invoice.date + (decoded_invoice.expiry or 0),
+            pubkey=None


Suggested change

pubkey=None

Optional parameter doesn't need definition

mypy was complaining about this because it's defined as optional but doesn't have a default value.

callebtc · 2024-11-15T14:10:26Z

cashu/wallet/wallet.py

+            privkey = PrivateKey(bytes.fromhex(quote_key), raw=True)
+            witness = nut19.sign_mint_quote(quote_id, outputs, privkey)


I would move the PrivateKey instantiation into the nut19 submodule

callebtc · 2024-11-15T14:11:17Z

cashu/wallet/wallet.py

@@ -424,13 +429,29 @@ async def request_mint(self, amount: int, memo: Optional[str] = None) -> MintQuo
        Returns:
            MintQuote: Mint Quote
        """
-        mint_quote_response = await super().mint_quote(amount, self.unit, memo)
+        privkey, pubkey = await self.get_quote_ephemeral_keypair()


Can we move get_quote_ephemeral_keypair also to nut19.py?

So if we later want to add derivation from seed+counter functionality we might want to keep it inside the wallet class.

In general depends on the state of the wallet so...

callebtc · 2024-11-15T14:13:18Z

The alternative is keeping the private key separate but still storing it together with the quote in the DB.

I think it should have two separate columns privatekey for the wallet and pubkey for the mint, so it's as explicit as possible.

…ot correctly escaped + pass in NUT-19 keypair to `request_mint` `request_mint_with_callback`

lollerfirst · 2024-11-17T17:53:28Z

I moved nuts.py to the nuts directory as well because I was getting some import errors.

lollerfirst and others added 7 commits November 13, 2024 01:06

nut-19 sign mint quote

01590b9

ephemeral key for quote

3b1109b

mint adjustments + crypto/nut19.py

59dc56f

wip: mint side working

369a49e

fix import

af616da

Merge remote-tracking branch 'upstream/nut-19-mint-quote-signature' i…

0e32c38

…nto nut-19

post-merge fixups

410d808