import asyncio import time from typing import Dict, List, Mapping, Optional, Tuple import bolt11 from loguru import logger from ..core.base import ( DLEQ, Amount, BlindedMessage, BlindedSignature, MeltQuote, MeltQuoteState, Method, MintKeyset, MintQuote, MintQuoteState, Proof, ProofSpentState, ProofState, Unit, ) from ..core.crypto import b_dhke from ..core.crypto.aes import AESCipher from ..core.crypto.keys import ( derive_pubkey, random_hash, ) from ..core.crypto.secp import PrivateKey, PublicKey from ..core.db import Connection, Database, get_db_connection from ..core.errors import ( CashuError, KeysetError, KeysetNotFoundError, LightningError, NotAllowedError, QuoteNotPaidError, TransactionError, ) from ..core.helpers import sum_proofs from ..core.models import ( PostMeltQuoteRequest, PostMeltQuoteResponse, PostMintQuoteRequest, ) from ..core.settings import settings from ..core.split import amount_split from ..lightning.base import ( InvoiceResponse, LightningBackend, PaymentQuoteResponse, PaymentStatus, ) from ..mint.crud import LedgerCrudSqlite from .conditions import LedgerSpendingConditions from .db.read import DbReadHelper from .db.write import DbWriteHelper from .events.events import LedgerEventManager from .features import LedgerFeatures from .tasks import LedgerTasks from .verification import LedgerVerification class Ledger(LedgerVerification, LedgerSpendingConditions, LedgerTasks, LedgerFeatures): backends: Mapping[Method, Mapping[Unit, LightningBackend]] = {} locks: Dict[str, asyncio.Lock] = {} # holds multiprocessing locks keysets: Dict[str, MintKeyset] = {} events = LedgerEventManager() db_read: DbReadHelper def __init__( self, db: Database, seed: str, backends: Mapping[Method, Mapping[Unit, LightningBackend]], seed_decryption_key: Optional[str] = None, derivation_path="", crud=LedgerCrudSqlite(), ): if not seed: raise Exception("seed not set") # decrypt seed if seed_decryption_key is set try: self.seed = ( AESCipher(seed_decryption_key).decrypt(seed) if seed_decryption_key else seed ) except Exception as e: raise Exception( f"Could not decrypt seed. Make sure that the seed is correct and the decryption key is set. {e}" ) self.derivation_path = derivation_path self.db = db self.crud = crud self.backends = backends self.pubkey = derive_pubkey(self.seed) self.db_read = DbReadHelper(self.db, self.crud) self.db_write = DbWriteHelper(self.db, self.crud, self.events) # ------- STARTUP ------- async def startup_ledger(self): await self._startup_ledger() await self._check_pending_proofs_and_melt_quotes() await self.dispatch_listeners() async def _startup_ledger(self): await self.init_keysets() for derivation_path in settings.mint_derivation_path_list: await self.activate_keyset(derivation_path=derivation_path) for method in self.backends: for unit in self.backends[method]: logger.info( f"Using {self.backends[method][unit].__class__.__name__} backend for" f" method: '{method.name}' and unit: '{unit.name}'" ) status = await self.backends[method][unit].status() if status.error_message: logger.warning( "The backend for" f" {self.backends[method][unit].__class__.__name__} isn't" f" working properly: '{status.error_message}'", RuntimeWarning, ) logger.info(f"Backend balance: {status.balance} {unit.name}") logger.info(f"Data dir: {settings.cashu_dir}") async def _check_pending_proofs_and_melt_quotes(self): """Startup routine that checks all pending proofs for their melt state and either invalidates them for a successful melt or deletes them if the melt failed. """ # get all pending melt quotes melt_quotes = await self.crud.get_all_melt_quotes_from_pending_proofs( db=self.db ) if not melt_quotes: return for quote in melt_quotes: # get pending proofs for quote pending_proofs = await self.crud.get_pending_proofs_for_quote( quote_id=quote.quote, db=self.db ) # check with the backend whether the quote has been paid during downtime payment = await self.backends[Method[quote.method]][ Unit[quote.unit] ].get_payment_status(quote.checking_id) if payment.paid: logger.info(f"Melt quote {quote.quote} state: paid") quote.paid_time = int(time.time()) quote.paid = True quote.state = MeltQuoteState.paid if payment.fee: quote.fee_paid = payment.fee.to(Unit[quote.unit]).amount quote.payment_preimage = payment.preimage or "" await self.crud.update_melt_quote(quote=quote, db=self.db) # invalidate proofs await self._invalidate_proofs( proofs=pending_proofs, quote_id=quote.quote ) # unset pending await self.db_write._unset_proofs_pending(pending_proofs) elif payment.failed: logger.info(f"Melt quote {quote.quote} state: failed") # unset pending await self.db_write._unset_proofs_pending(pending_proofs, spent=False) elif payment.pending: logger.info(f"Melt quote {quote.quote} state: pending") pass else: logger.error("Melt quote state unknown") pass # ------- KEYS ------- async def activate_keyset( self, *, derivation_path: str, seed: Optional[str] = None, version: Optional[str] = None, autosave=True, ) -> MintKeyset: """Load the keyset for a derivation path if it already exists. If not generate new one and store in the db. Args: derivation_path (_type_): Derivation path from which the keyset is generated. autosave (bool, optional): Store newly-generated keyset if not already in database. Defaults to True. Returns: MintKeyset: Keyset """ if not derivation_path: raise Exception("derivation path not set") seed = seed or self.seed tmp_keyset_local = MintKeyset( seed=seed, derivation_path=derivation_path, version=version or settings.version, ) logger.debug( f"Activating keyset for derivation path {derivation_path} with id" f" {tmp_keyset_local.id}." ) # load the keyset from db logger.trace(f"crud: loading keyset for {derivation_path}") tmp_keysets_local: List[MintKeyset] = await self.crud.get_keyset( id=tmp_keyset_local.id, db=self.db ) logger.trace(f"crud: loaded {len(tmp_keysets_local)} keysets") if tmp_keysets_local: # we have a keyset with this derivation path in the database keyset = tmp_keysets_local[0] else: # no keyset for this derivation path yet # we create a new keyset (keys will be generated at instantiation) keyset = MintKeyset( seed=seed or self.seed, derivation_path=derivation_path, version=version or settings.version, input_fee_ppk=settings.mint_input_fee_ppk, ) logger.debug(f"Generated new keyset {keyset.id}.") if autosave: logger.debug(f"crud: storing new keyset {keyset.id}.") await self.crud.store_keyset(keyset=keyset, db=self.db) logger.trace(f"crud: stored new keyset {keyset.id}.") # activate this keyset keyset.active = True # load the new keyset in self.keysets self.keysets[keyset.id] = keyset logger.debug(f"Loaded keyset {keyset.id}") return keyset async def init_keysets(self, autosave: bool = True) -> None: """Initializes all keysets of the mint from the db. Loads all past keysets from db and generate their keys. Then activate the current keyset set by self.derivation_path. Args: autosave (bool, optional): Whether the current keyset should be saved if it is not in the database yet. Will be passed to `self.activate_keyset` where it is generated from `self.derivation_path`. Defaults to True. """ # load all past keysets from db, the keys will be generated at instantiation tmp_keysets: List[MintKeyset] = await self.crud.get_keyset(db=self.db) # add keysets from db to memory for k in tmp_keysets: self.keysets[k.id] = k logger.info(f"Loaded {len(self.keysets)} keysets from database.") # activate the current keyset set by self.derivation_path if self.derivation_path: self.keyset = await self.activate_keyset( derivation_path=self.derivation_path, autosave=autosave ) logger.info(f"Current keyset: {self.keyset.id}") # check that we have a least one active keyset if not any([k.active for k in self.keysets.values()]): raise KeysetError("No active keyset found.") def get_keyset(self, keyset_id: Optional[str] = None) -> Dict[int, str]: """Returns a dictionary of hex public keys of a specific keyset for each supported amount""" if keyset_id and keyset_id not in self.keysets: raise KeysetNotFoundError() keyset = self.keysets[keyset_id] if keyset_id else self.keyset if not keyset.public_keys: raise KeysetError("no public keys for this keyset") return {a: p.serialize().hex() for a, p in keyset.public_keys.items()} async def get_balance(self) -> int: """Returns the balance of the mint.""" return await self.crud.get_balance(db=self.db) # ------- ECASH ------- async def _invalidate_proofs( self, *, proofs: List[Proof], quote_id: Optional[str] = None, conn: Optional[Connection] = None, ) -> None: """Adds proofs to the set of spent proofs and stores them in the db. Args: proofs (List[Proof]): Proofs to add to known secret table. conn: (Optional[Connection], optional): Database connection to reuse. Will create a new one if not given. Defaults to None. """ async with get_db_connection(self.db, conn) as conn: # store in db for p in proofs: await self.crud.invalidate_proof( proof=p, db=self.db, quote_id=quote_id, conn=conn ) await self.events.submit( ProofState( Y=p.Y, state=ProofSpentState.spent, witness=p.witness or None ) ) async def _generate_change_promises( self, fee_provided: int, fee_paid: int, outputs: Optional[List[BlindedMessage]], keyset: Optional[MintKeyset] = None, ) -> List[BlindedSignature]: """Generates a set of new promises (blinded signatures) from a set of blank outputs (outputs with no or ignored amount) by looking at the difference between the Lightning fee reserve provided by the wallet and the actual Lightning fee paid by the mint. If there is a positive difference, produces maximum `n_return_outputs` new outputs with values close or equal to the fee difference. If the given number of `outputs` matches the equation defined in NUT-08, we can be sure to return the overpaid fee perfectly. Otherwise, a smaller amount will be returned. Args: input_amount (int): Amount of the proofs provided by the client. output_amount (int): Amount of the melt request to be paid. output_fee_paid (int): Actually paid melt network fees. outputs (Optional[List[BlindedMessage]]): Outputs to sign for returning the overpaid fees. Raises: Exception: Output validation failed. Returns: List[BlindedSignature]: Signatures on the outputs. """ # we make sure that the fee is positive overpaid_fee = fee_provided - fee_paid if overpaid_fee == 0 or outputs is None: return [] logger.debug( f"Lightning fee was: {fee_paid}. User provided: {fee_provided}. " f"Returning difference: {overpaid_fee}." ) return_amounts = amount_split(overpaid_fee) # We return at most as many outputs as were provided or as many as are # required to pay back the overpaid fee. n_return_outputs = min(len(outputs), len(return_amounts)) # we only need as many outputs as we have change to return outputs = outputs[:n_return_outputs] # we sort the return_amounts in descending order so we only # take the largest values in the next step return_amounts_sorted = sorted(return_amounts, reverse=True) # we need to imprint these amounts into the blanket outputs for i in range(len(outputs)): outputs[i].amount = return_amounts_sorted[i] # type: ignore if not self._verify_no_duplicate_outputs(outputs): raise TransactionError("duplicate promises.") return_promises = await self._generate_promises(outputs, keyset) return return_promises # ------- TRANSACTIONS ------- async def mint_quote(self, quote_request: PostMintQuoteRequest) -> MintQuote: """Creates a mint quote and stores it in the database. Args: quote_request (PostMintQuoteRequest): Mint quote request. Raises: Exception: Quote creation failed. Returns: MintQuote: Mint quote object. """ logger.trace("called request_mint") if not quote_request.amount > 0: raise TransactionError("amount must be positive") if settings.mint_max_peg_in and quote_request.amount > settings.mint_max_peg_in: raise NotAllowedError( f"Maximum mint amount is {settings.mint_max_peg_in} sat." ) if settings.mint_peg_out_only: raise NotAllowedError("Mint does not allow minting new tokens.") unit, method = self._verify_and_get_unit_method( quote_request.unit, Method.bolt11.name ) if settings.mint_max_balance: balance = await self.get_balance() if balance + quote_request.amount > settings.mint_max_balance: raise NotAllowedError("Mint has reached maximum balance.") logger.trace(f"requesting invoice for {unit.str(quote_request.amount)}") invoice_response: InvoiceResponse = await self.backends[method][ unit ].create_invoice(Amount(unit=unit, amount=quote_request.amount)) logger.trace( f"got invoice {invoice_response.payment_request} with checking id" f" {invoice_response.checking_id}" ) if not (invoice_response.payment_request and invoice_response.checking_id): raise LightningError("could not fetch bolt11 payment request from backend") # get invoice expiry time invoice_obj = bolt11.decode(invoice_response.payment_request) # NOTE: we normalize the request to lowercase to avoid case sensitivity # This works with Lightning but might not work with other methods request = invoice_response.payment_request.lower() expiry = None if invoice_obj.expiry is not None: expiry = invoice_obj.date + invoice_obj.expiry quote = MintQuote( quote=random_hash(), method=method.name, request=request, checking_id=invoice_response.checking_id, unit=quote_request.unit, amount=quote_request.amount, issued=False, paid=False, state=MintQuoteState.unpaid, created_time=int(time.time()), expiry=expiry, ) await self.crud.store_mint_quote(quote=quote, db=self.db) await self.events.submit(quote) return quote async def get_mint_quote(self, quote_id: str) -> MintQuote: """Returns a mint quote. If the quote is not paid, checks with the backend if the associated request is paid. Args: quote_id (str): ID of the mint quote. Raises: Exception: Quote not found. Returns: MintQuote: Mint quote object. """ quote = await self.crud.get_mint_quote(quote_id=quote_id, db=self.db) if not quote: raise Exception("quote not found") unit, method = self._verify_and_get_unit_method(quote.unit, quote.method) if quote.state == MintQuoteState.unpaid: if not quote.checking_id: raise CashuError("quote has no checking id") logger.trace(f"Lightning: checking invoice {quote.checking_id}") status: PaymentStatus = await self.backends[method][ unit ].get_invoice_status(quote.checking_id) if status.paid: logger.trace(f"Setting quote {quote_id} as paid") quote.paid = True quote.state = MintQuoteState.paid quote.paid_time = int(time.time()) await self.crud.update_mint_quote(quote=quote, db=self.db) await self.events.submit(quote) return quote async def mint( self, *, outputs: List[BlindedMessage], quote_id: str, ) -> 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. Raises: Exception: Validation of outputs failed. Exception: Quote not paid. Exception: Quote already issued. Exception: Quote expired. Exception: Amount to mint does not match quote amount. Returns: List[BlindedSignature]: Signatures on the outputs. """ logger.trace("called mint") await self._verify_outputs(outputs) sum_amount_outputs = sum([b.amount for b in outputs]) # we already know from _verify_outputs that all outputs have the same unit because they have the same keyset output_unit = self.keysets[outputs[0].id].unit self.locks[quote_id] = ( self.locks.get(quote_id) or asyncio.Lock() ) # create a new lock if it doesn't exist async with self.locks[quote_id]: quote = await self.get_mint_quote(quote_id=quote_id) if not quote.paid: raise QuoteNotPaidError() if quote.issued: raise TransactionError("quote already issued") if not quote.state == MintQuoteState.paid: raise QuoteNotPaidError() if quote.state == MintQuoteState.issued: raise TransactionError("quote already issued") if not quote.unit == output_unit.name: raise TransactionError("quote unit does not match output unit") if not quote.amount == sum_amount_outputs: raise TransactionError("amount to mint does not match quote amount") if quote.expiry and quote.expiry > int(time.time()): raise TransactionError("quote expired") logger.trace(f"crud: setting quote {quote_id} as issued") quote.issued = True quote.state = MintQuoteState.issued await self.crud.update_mint_quote(quote=quote, db=self.db) promises = await self._generate_promises(outputs) logger.trace("generated promises") # submit the quote update to the event manager await self.events.submit(quote) del self.locks[quote_id] return promises def create_internal_melt_quote( self, mint_quote: MintQuote, melt_quote: PostMeltQuoteRequest ) -> PaymentQuoteResponse: unit, method = self._verify_and_get_unit_method( melt_quote.unit, Method.bolt11.name ) # NOTE: we normalize the request to lowercase to avoid case sensitivity # This works with Lightning but might not work with other methods request = melt_quote.request.lower() if not request == mint_quote.request: raise TransactionError("bolt11 requests do not match") if not mint_quote.unit == melt_quote.unit: raise TransactionError("units do not match") if not mint_quote.method == method.name: raise TransactionError("methods do not match") if mint_quote.paid: raise TransactionError("mint quote already paid") if mint_quote.issued: raise TransactionError("mint quote already issued") if mint_quote.state == MintQuoteState.issued: raise TransactionError("mint quote already issued") if mint_quote.state != MintQuoteState.unpaid: raise TransactionError("mint quote already paid") if not mint_quote.checking_id: raise TransactionError("mint quote has no checking id") if melt_quote.is_mpp: raise TransactionError("internal payments do not support mpp") internal_fee = Amount(unit, 0) # no internal fees amount = Amount(unit, mint_quote.amount) payment_quote = PaymentQuoteResponse( checking_id=mint_quote.checking_id, amount=amount, fee=internal_fee, ) logger.info( f"Issuing internal melt quote: {request} ->" f" {mint_quote.quote} ({amount.str()} + {internal_fee.str()} fees)" ) return payment_quote def validate_payment_quote( self, melt_quote: PostMeltQuoteRequest, payment_quote: PaymentQuoteResponse ): # payment quote validation unit, method = self._verify_and_get_unit_method( melt_quote.unit, Method.bolt11.name ) if not payment_quote.checking_id: raise Exception("quote has no checking id") # verify that payment quote amount is as expected if melt_quote.is_mpp and melt_quote.mpp_amount != payment_quote.amount.amount: raise TransactionError("quote amount not as requested") # make sure the backend returned the amount with a correct unit if not payment_quote.amount.unit == unit: raise TransactionError("payment quote amount units do not match") # fee from the backend must be in the same unit as the amount if not payment_quote.fee.unit == unit: raise TransactionError("payment quote fee units do not match") async def melt_quote( self, melt_quote: PostMeltQuoteRequest ) -> PostMeltQuoteResponse: """Creates a melt quote and stores it in the database. Args: melt_quote (PostMeltQuoteRequest): Melt quote request. Raises: Exception: Quote invalid. Exception: Quote already paid. Exception: Quote already issued. Returns: PostMeltQuoteResponse: Melt quote response. """ unit, method = self._verify_and_get_unit_method( melt_quote.unit, Method.bolt11.name ) # NOTE: we normalize the request to lowercase to avoid case sensitivity # This works with Lightning but might not work with other methods request = melt_quote.request.lower() # check if there is a mint quote with the same payment request # so that we would be able to handle the transaction internally # and therefore respond with internal transaction fees (0 for now) mint_quote = await self.crud.get_mint_quote(request=request, db=self.db) if mint_quote: payment_quote = self.create_internal_melt_quote(mint_quote, melt_quote) else: # not internal # verify that the backend supports mpp if the quote request has an amount if melt_quote.is_mpp and not self.backends[method][unit].supports_mpp: raise TransactionError("backend does not support mpp") # get payment quote by backend payment_quote = await self.backends[method][unit].get_payment_quote( melt_quote=melt_quote ) self.validate_payment_quote(melt_quote, payment_quote) # verify that the amount of the proofs is not larger than the maximum allowed if ( settings.mint_max_peg_out and payment_quote.amount.to(unit).amount > settings.mint_max_peg_out ): raise NotAllowedError( f"Maximum melt amount is {settings.mint_max_peg_out} sat." ) # We assume that the request is a bolt11 invoice, this works since we # support only the bol11 method for now. invoice_obj = bolt11.decode(melt_quote.request) if not invoice_obj.amount_msat: raise TransactionError("invoice has no amount.") # we set the expiry of this quote to the expiry of the bolt11 invoice expiry = None if invoice_obj.expiry is not None: expiry = invoice_obj.date + invoice_obj.expiry quote = MeltQuote( quote=random_hash(), method=method.name, request=request, checking_id=payment_quote.checking_id, unit=unit.name, amount=payment_quote.amount.to(unit).amount, paid=False, state=MeltQuoteState.unpaid, fee_reserve=payment_quote.fee.to(unit).amount, created_time=int(time.time()), expiry=expiry, ) await self.crud.store_melt_quote(quote=quote, db=self.db) await self.events.submit(quote) return PostMeltQuoteResponse( quote=quote.quote, amount=quote.amount, fee_reserve=quote.fee_reserve, paid=quote.paid, state=quote.state.value, expiry=quote.expiry, ) async def get_melt_quote(self, quote_id: str) -> MeltQuote: """Returns a melt quote. If melt quote is not paid yet and no internal mint quote is associated with it, checks with the backend for the state of the payment request. If the backend says that the quote has been paid, updates the melt quote in the database. Args: quote_id (str): ID of the melt quote. Raises: Exception: Quote not found. Returns: MeltQuote: Melt quote object. """ melt_quote = await self.crud.get_melt_quote(quote_id=quote_id, db=self.db) if not melt_quote: raise Exception("quote not found") unit, method = self._verify_and_get_unit_method( melt_quote.unit, melt_quote.method ) # we only check the state with the backend if there is no associated internal # mint quote for this melt quote mint_quote = await self.crud.get_mint_quote( request=melt_quote.request, db=self.db ) if not melt_quote.paid and not mint_quote: logger.trace( "Lightning: checking outgoing Lightning payment" f" {melt_quote.checking_id}" ) status: PaymentStatus = await self.backends[method][ unit ].get_payment_status(melt_quote.checking_id) if status.paid: logger.trace(f"Setting quote {quote_id} as paid") melt_quote.paid = True melt_quote.state = MeltQuoteState.paid if status.fee: melt_quote.fee_paid = status.fee.to(unit).amount if status.preimage: melt_quote.payment_preimage = status.preimage melt_quote.paid_time = int(time.time()) await self.crud.update_melt_quote(quote=melt_quote, db=self.db) await self.events.submit(melt_quote) return melt_quote async def melt_mint_settle_internally( self, melt_quote: MeltQuote, proofs: List[Proof] ) -> MeltQuote: """Settles a melt quote internally if there is a mint quote with the same payment request. `proofs` are passed to determine the ecash input transaction fees for this melt quote. Args: melt_quote (MeltQuote): Melt quote to settle. proofs (List[Proof]): Proofs provided for paying the Lightning invoice. Raises: Exception: Melt quote already paid. Exception: Melt quote already issued. Returns: MeltQuote: Settled melt quote. """ # first we check if there is a mint quote with the same payment request # so that we can handle the transaction internally without the backend mint_quote = await self.crud.get_mint_quote( request=melt_quote.request, db=self.db ) if not mint_quote: return melt_quote # we settle the transaction internally if melt_quote.paid: raise TransactionError("melt quote already paid") if melt_quote.state != MeltQuoteState.unpaid: raise TransactionError("melt quote already paid") # verify amounts from bolt11 invoice bolt11_request = melt_quote.request invoice_obj = bolt11.decode(bolt11_request) if not invoice_obj.amount_msat: raise TransactionError("invoice has no amount.") if not mint_quote.amount == melt_quote.amount: raise TransactionError("amounts do not match") if not bolt11_request == mint_quote.request: raise TransactionError("bolt11 requests do not match") if not mint_quote.unit == melt_quote.unit: raise TransactionError("units do not match") if not mint_quote.method == melt_quote.method: raise TransactionError("methods do not match") if mint_quote.paid: raise TransactionError("mint quote already paid") if mint_quote.issued: raise TransactionError("mint quote already issued") if mint_quote.state != MintQuoteState.unpaid: raise TransactionError("mint quote already paid") logger.info( f"Settling bolt11 payment internally: {melt_quote.quote} ->" f" {mint_quote.quote} ({melt_quote.amount} {melt_quote.unit})" ) melt_quote.fee_paid = 0 # no internal fees melt_quote.paid = True melt_quote.state = MeltQuoteState.paid melt_quote.paid_time = int(time.time()) mint_quote.paid = True mint_quote.state = MintQuoteState.paid mint_quote.paid_time = melt_quote.paid_time async with get_db_connection(self.db) as conn: await self.crud.update_melt_quote(quote=melt_quote, db=self.db, conn=conn) await self.crud.update_mint_quote(quote=mint_quote, db=self.db, conn=conn) await self.events.submit(melt_quote) await self.events.submit(mint_quote) return melt_quote async def melt( self, *, proofs: List[Proof], quote: str, outputs: Optional[List[BlindedMessage]] = None, ) -> PostMeltQuoteResponse: """Invalidates proofs and pays a Lightning invoice. Args: proofs (List[Proof]): Proofs provided for paying the Lightning invoice quote (str): ID of the melt quote. outputs (Optional[List[BlindedMessage]]): Blank outputs for returning overpaid fees to the wallet. Raises: e: Lightning payment unsuccessful Returns: Tuple[str, List[BlindedMessage]]: Proof of payment and signed outputs for returning overpaid fees to wallet. """ # get melt quote and check if it was already paid melt_quote = await self.get_melt_quote(quote_id=quote) unit, method = self._verify_and_get_unit_method( melt_quote.unit, melt_quote.method ) if melt_quote.state != MeltQuoteState.unpaid: raise TransactionError("melt quote already paid") # make sure that the outputs (for fee return) are in the same unit as the quote if outputs: # _verify_outputs checks if all outputs have the same unit await self._verify_outputs(outputs, skip_amount_check=True) outputs_unit = self.keysets[outputs[0].id].unit if not melt_quote.unit == outputs_unit.name: raise TransactionError( f"output unit {outputs_unit.name} does not match quote unit {melt_quote.unit}" ) # verify that the amount of the input proofs is equal to the amount of the quote total_provided = sum_proofs(proofs) input_fees = self.get_fees_for_proofs(proofs) total_needed = melt_quote.amount + melt_quote.fee_reserve + input_fees # we need the fees specifically for lightning to return the overpaid fees fee_reserve_provided = total_provided - melt_quote.amount - input_fees if total_provided < total_needed: raise TransactionError( f"not enough inputs provided for melt. Provided: {total_provided}, needed: {total_needed}" ) if fee_reserve_provided < melt_quote.fee_reserve: raise TransactionError( f"not enough fee reserve provided for melt. Provided fee reserve: {fee_reserve_provided}, needed: {melt_quote.fee_reserve}" ) # verify that the amount of the proofs is not larger than the maximum allowed if settings.mint_max_peg_out and total_provided > settings.mint_max_peg_out: raise NotAllowedError( f"Maximum melt amount is {settings.mint_max_peg_out} sat." ) # verify inputs and their spending conditions # note, we do not verify outputs here, as they are only used for returning overpaid fees # we should have used _verify_outputs here already (see above) await self.verify_inputs_and_outputs(proofs=proofs) # set proofs to pending to avoid race conditions await self.db_write._set_proofs_pending(proofs, quote_id=melt_quote.quote) try: # settle the transaction internally if there is a mint quote with the same payment request melt_quote = await self.melt_mint_settle_internally(melt_quote, proofs) # quote not paid yet (not internal), pay it with the backend if not melt_quote.paid and melt_quote.state == MeltQuoteState.unpaid: logger.debug(f"Lightning: pay invoice {melt_quote.request}") payment = await self.backends[method][unit].pay_invoice( melt_quote, melt_quote.fee_reserve * 1000 ) logger.debug( f"Melt – Ok: {payment.ok}: preimage: {payment.preimage}," f" fee: {payment.fee.str() if payment.fee is not None else 'None'}" ) if not payment.ok: raise LightningError( f"Lightning payment unsuccessful. {payment.error_message}" ) if payment.fee: melt_quote.fee_paid = payment.fee.to( to_unit=unit, round="up" ).amount if payment.preimage: melt_quote.payment_preimage = payment.preimage # set quote as paid melt_quote.paid = True melt_quote.state = MeltQuoteState.paid melt_quote.paid_time = int(time.time()) # melt successful, invalidate proofs await self._invalidate_proofs(proofs=proofs, quote_id=melt_quote.quote) # prepare change to compensate wallet for overpaid fees return_promises: List[BlindedSignature] = [] if outputs: return_promises = await self._generate_change_promises( fee_provided=fee_reserve_provided, fee_paid=melt_quote.fee_paid, outputs=outputs, keyset=self.keysets[outputs[0].id], ) melt_quote.change = return_promises await self.crud.update_melt_quote(quote=melt_quote, db=self.db) await self.events.submit(melt_quote) except Exception as e: logger.trace(f"Melt exception: {e}") raise e finally: # delete proofs from pending list await self.db_write._unset_proofs_pending(proofs) return PostMeltQuoteResponse.from_melt_quote(melt_quote) async def split( self, *, proofs: List[Proof], outputs: List[BlindedMessage], keyset: Optional[MintKeyset] = None, ): """Consumes proofs and prepares new promises based on the amount split. Used for splitting tokens Before sending or for redeeming tokens for new ones that have been received by another wallet. Args: proofs (List[Proof]): Proofs to be invalidated for the split. outputs (List[BlindedMessage]): New outputs that should be signed in return. keyset (Optional[MintKeyset], optional): Keyset to use. Uses default keyset if not given. Defaults to None. Raises: Exception: Validation of proofs or outputs failed Returns: Tuple[List[BlindSignature],List[BlindSignature]]: Promises on both sides of the split. """ logger.trace("split called") # explicitly check that amount of inputs is equal to amount of outputs # note: we check this again in verify_inputs_and_outputs but only if any # outputs are provided at all. To make sure of that before calling # verify_inputs_and_outputs, we check it here. self._verify_equation_balanced(proofs, outputs) # verify spending inputs, outputs, and spending conditions await self.verify_inputs_and_outputs(proofs=proofs, outputs=outputs) await self.db_write._set_proofs_pending(proofs) try: # Mark proofs as used and prepare new promises async with get_db_connection(self.db) as conn: # we do this in a single db transaction await self._invalidate_proofs(proofs=proofs, conn=conn) promises = await self._generate_promises(outputs, keyset, conn) except Exception as e: logger.trace(f"split failed: {e}") raise e finally: # delete proofs from pending list await self.db_write._unset_proofs_pending(proofs) logger.trace("split successful") return promises async def restore( self, outputs: List[BlindedMessage] ) -> Tuple[List[BlindedMessage], List[BlindedSignature]]: signatures: List[BlindedSignature] = [] return_outputs: List[BlindedMessage] = [] async with get_db_connection(self.db) as conn: for output in outputs: logger.trace(f"looking for promise: {output}") promise = await self.crud.get_promise( b_=output.B_, db=self.db, conn=conn ) if promise is not None: signatures.append(promise) return_outputs.append(output) logger.trace(f"promise found: {promise}") return return_outputs, signatures # ------- BLIND SIGNATURES ------- async def _generate_promises( self, outputs: List[BlindedMessage], keyset: Optional[MintKeyset] = None, conn: Optional[Connection] = None, ) -> list[BlindedSignature]: """Generates a promises (Blind signatures) for given amount and returns a pair (amount, C'). Important: When a promises is once created it should be considered issued to the user since the user will always be able to restore promises later through the backup restore endpoint. That means that additional checks in the code that might decide not to return these promises should be avoided once this function is called. Only call this function if the transaction is fully validated! Args: B_s (List[BlindedMessage]): Blinded secret (point on curve) keyset (Optional[MintKeyset], optional): Which keyset to use. Private keys will be taken from this keyset. If not given will use the keyset of the first output. Defaults to None. conn: (Optional[Connection], optional): Database connection to reuse. Will create a new one if not given. Defaults to None. Returns: list[BlindedSignature]: Generated BlindedSignatures. """ promises: List[ Tuple[str, PublicKey, int, PublicKey, PrivateKey, PrivateKey] ] = [] for output in outputs: B_ = PublicKey(bytes.fromhex(output.B_), raw=True) keyset = keyset or self.keysets[output.id] if output.id not in self.keysets: raise TransactionError(f"keyset {output.id} not found") if output.id != keyset.id: raise TransactionError("keyset id does not match output id") if not keyset.active: raise TransactionError("keyset is not active") keyset_id = output.id logger.trace(f"Generating promise with keyset {keyset_id}.") private_key_amount = keyset.private_keys[output.amount] C_, e, s = b_dhke.step2_bob(B_, private_key_amount) promises.append((keyset_id, B_, output.amount, C_, e, s)) keyset = keyset or self.keyset signatures = [] async with get_db_connection(self.db, conn) as conn: for promise in promises: keyset_id, B_, amount, C_, e, s = promise logger.trace(f"crud: _generate_promise storing promise for {amount}") await self.crud.store_promise( amount=amount, id=keyset_id, b_=B_.serialize().hex(), c_=C_.serialize().hex(), e=e.serialize(), s=s.serialize(), db=self.db, conn=conn, ) logger.trace(f"crud: _generate_promise stored promise for {amount}") signature = BlindedSignature( id=keyset_id, amount=amount, C_=C_.serialize().hex(), dleq=DLEQ(e=e.serialize(), s=s.serialize()), ) signatures.append(signature) return signatures