feat: generate keys

lnbits/extensions/cashu/core/secp.py

@@ -0,0 +1,52 @@
+from secp256k1 import PrivateKey, PublicKey
+
+
+# We extend the public key to define some operations on points
+# Picked from https://github.com/WTRMQDev/secp256k1-zkp-py/blob/master/secp256k1_zkp/__init__.py
+class PublicKeyExt(PublicKey):
+    def __add__(self, pubkey2):
+        if isinstance(pubkey2, PublicKey):
+            new_pub = PublicKey()
+            new_pub.combine([self.public_key, pubkey2.public_key])
+            return new_pub
+        else:
+            raise TypeError("Cant add pubkey and %s" % pubkey2.__class__)
+
+    def __neg__(self):
+        serialized = self.serialize()
+        first_byte, remainder = serialized[:1], serialized[1:]
+        # flip odd/even byte
+        first_byte = {b"\x03": b"\x02", b"\x02": b"\x03"}[first_byte]
+        return PublicKey(first_byte + remainder, raw=True)
+
+    def __sub__(self, pubkey2):
+        if isinstance(pubkey2, PublicKey):
+            return self + (-pubkey2)
+        else:
+            raise TypeError("Can't add pubkey and %s" % pubkey2.__class__)
+
+    def mult(self, privkey):
+        if isinstance(privkey, PrivateKey):
+            return self.tweak_mul(privkey.private_key)
+        else:
+            raise TypeError("Can't multiply with non privatekey")
+
+    def __eq__(self, pubkey2):
+        if isinstance(pubkey2, PublicKey):
+            seq1 = self.to_data()
+            seq2 = pubkey2.to_data()
+            return seq1 == seq2
+        else:
+            raise TypeError("Can't compare pubkey and %s" % pubkey2.__class__)
+
+    def to_data(self):
+        return [self.public_key.data[i] for i in range(64)]
+
+
+# Horrible monkeypatching
+PublicKey.__add__ = PublicKeyExt.__add__
+PublicKey.__neg__ = PublicKeyExt.__neg__
+PublicKey.__sub__ = PublicKeyExt.__sub__
+PublicKey.mult = PublicKeyExt.mult
+PublicKey.__eq__ = PublicKeyExt.__eq__
+PublicKey.to_data = PublicKeyExt.to_data

lnbits/extensions/cashu/mint.py

@@ -0,0 +1,12 @@
+
+from .crud import get_cashu
+from .mint_helper import derive_keys, derive_pubkeys
+
+
+def get_pubkeys(xpriv: str):
+    """Returns public keys for possible amounts."""
+    
+    keys = derive_keys(xpriv)
+    pub_keys = derive_pubkeys(keys)
+
+    return {a: p.serialize().hex() for a, p in pub_keys.items()}

lnbits/extensions/cashu/mint_helper.py

@@ -0,0 +1,22 @@
+import hashlib
+from typing import List, Set
+from .core.secp import PrivateKey, PublicKey
+
+# todo: extract const
+MAX_ORDER = 64
+
+def derive_keys(master_key: str):
+    """Deterministic derivation of keys for 2^n values."""
+    return {
+        2
+        ** i: PrivateKey(
+            hashlib.sha256((str(master_key) + str(i)).encode("utf-8"))
+            .hexdigest()
+            .encode("utf-8")[:32],
+            raw=True,
+        )
+        for i in range(MAX_ORDER)
+    }
+
+def derive_pubkeys(keys: List[PrivateKey]):
+    return {amt: keys[amt].pubkey for amt in [2**i for i in range(MAX_ORDER)]}

lnbits/extensions/cashu/views_api.py

@@ -15,7 +15,8 @@ from lnbits.core.views.api import api_payment
 from lnbits.decorators import WalletTypeInfo, get_key_type, require_admin_key
 
 from . import cashu_ext
-from .ledger import get_pubkeys, request_mint, mint
+from .ledger import request_mint, mint
+from .mint import get_pubkeys
 
 from .crud import (
     create_cashu, 
@@ -35,6 +36,11 @@ from .models import (
     PayLnurlWData
 )
 
+########################################
+#################MINT CRUD##############
+########################################
+
+# todo: use /mints
 @cashu_ext.get("/api/v1/cashus", status_code=HTTPStatus.OK)
 async def api_cashus(
     all_wallets: bool = Query(False), wallet: WalletTypeInfo = Depends(get_key_type)
@@ -83,6 +89,9 @@ async def api_cashu_delete(
     raise HTTPException(status_code=HTTPStatus.NO_CONTENT)
 
 
+########################################
+#################????###################
+########################################
 @cashu_ext.post("/api/v1/cashus/{cashu_id}/invoices", status_code=HTTPStatus.CREATED)
 async def api_cashu_create_invoice(
     amount: int = Query(..., ge=1), tipAmount: int = None, cashu_id: str = None
@@ -192,10 +201,16 @@ async def api_cashu_check_invoice(cashu_id: str, payment_hash: str):
 #################MINT###################
 ########################################
 
-@cashu_ext.get("/keys")
-def keys(cashu_id: str):
+@cashu_ext.get("/api/v1/mint/keys/{cashu_id}",  status_code=HTTPStatus.OK)
+async def keys(cashu_id: str = Query(False), wallet: WalletTypeInfo = Depends(get_key_type)):
     """Get the public keys of the mint"""
-    return get_pubkeys(cashu_id)
+    print('############################')
+    mint = await get_cashu(cashu_id)
+    if mint is None:
+        raise HTTPException(
+                    status_code=HTTPStatus.NOT_FOUND, detail="Mint does not exist."
+                )
+    return get_pubkeys(mint.prvkey)
 
 
 @cashu_ext.get("/mint")