Revert "Wallet: deprecate old hash to curve (#457)"

This reverts commit b06d93c.

cashu/core/crypto/b_dhke.py

@@ -55,10 +55,26 @@
 
 from secp256k1 import PrivateKey, PublicKey
 
+
+def hash_to_curve(message: bytes) -> PublicKey:
+    """Generates a point from the message hash and checks if the point lies on the curve.
+    If it does not, iteratively tries to compute a new point from the hash."""
+    point = None
+    msg_to_hash = message
+    while point is None:
+        _hash = hashlib.sha256(msg_to_hash).digest()
+        try:
+            # will error if point does not lie on curve
+            point = PublicKey(b"\x02" + _hash, raw=True)
+        except Exception:
+            msg_to_hash = _hash
+    return point
+
+
 DOMAIN_SEPARATOR = b"Secp256k1_HashToCurve_Cashu_"
 
 
-def hash_to_curve(message: bytes) -> PublicKey:
+def hash_to_curve_domain_separated(message: bytes) -> PublicKey:
     """Generates a secp256k1 point from a message.
 
     The point is generated by hashing the message with a domain separator and then
@@ -94,6 +110,15 @@ def step1_alice(
     return B_, r
 
 
+def step1_alice_domain_separated(
+    secret_msg: str, blinding_factor: Optional[PrivateKey] = None
+) -> tuple[PublicKey, PrivateKey]:
+    Y: PublicKey = hash_to_curve_domain_separated(secret_msg.encode("utf-8"))
+    r = blinding_factor or PrivateKey()
+    B_: PublicKey = Y + r.pubkey  # type: ignore
+    return B_, r
+
+
 def step2_bob(B_: PublicKey, a: PrivateKey) -> Tuple[PublicKey, PrivateKey, PrivateKey]:
     C_: PublicKey = B_.mult(a)  # type: ignore
     # produce dleq proof
@@ -111,11 +136,17 @@ def verify(a: PrivateKey, C: PublicKey, secret_msg: str) -> bool:
     valid = C == Y.mult(a)  # type: ignore
     # BEGIN: BACKWARDS COMPATIBILITY < 0.15.1
     if not valid:
-        valid = verify_deprecated(a, C, secret_msg)
+        valid = verify_domain_separated(a, C, secret_msg)
     # END: BACKWARDS COMPATIBILITY < 0.15.1
     return valid
 
 
+def verify_domain_separated(a: PrivateKey, C: PublicKey, secret_msg: str) -> bool:
+    Y: PublicKey = hash_to_curve_domain_separated(secret_msg.encode("utf-8"))
+    valid = C == Y.mult(a)  # type: ignore
+    return valid
+
+
 def hash_e(*publickeys: PublicKey) -> bytes:
     e_ = ""
     for p in publickeys:
@@ -171,53 +202,20 @@ def carol_verify_dleq(
     valid = alice_verify_dleq(B_, C_, e, s, A)
     # BEGIN: BACKWARDS COMPATIBILITY < 0.15.1
     if not valid:
-        return carol_verify_dleq_deprecated(secret_msg, r, C, e, s, A)
+        return carol_verify_dleq_domain_separated(secret_msg, r, C, e, s, A)
     # END: BACKWARDS COMPATIBILITY < 0.15.1
     return valid
 
 
-# -------- Deprecated hash_to_curve before 0.15.0 --------
-
-
-def hash_to_curve_deprecated(message: bytes) -> PublicKey:
-    """Generates a point from the message hash and checks if the point lies on the curve.
-    If it does not, iteratively tries to compute a new point from the hash."""
-    point = None
-    msg_to_hash = message
-    while point is None:
-        _hash = hashlib.sha256(msg_to_hash).digest()
-        try:
-            # will error if point does not lie on curve
-            point = PublicKey(b"\x02" + _hash, raw=True)
-        except Exception:
-            msg_to_hash = _hash
-    return point
-
-
-def step1_alice_deprecated(
-    secret_msg: str, blinding_factor: Optional[PrivateKey] = None
-) -> tuple[PublicKey, PrivateKey]:
-    Y: PublicKey = hash_to_curve_deprecated(secret_msg.encode("utf-8"))
-    r = blinding_factor or PrivateKey()
-    B_: PublicKey = Y + r.pubkey  # type: ignore
-    return B_, r
-
-
-def verify_deprecated(a: PrivateKey, C: PublicKey, secret_msg: str) -> bool:
-    Y: PublicKey = hash_to_curve_deprecated(secret_msg.encode("utf-8"))
-    valid = C == Y.mult(a)  # type: ignore
-    return valid
-
-
-def carol_verify_dleq_deprecated(
+def carol_verify_dleq_domain_separated(
     secret_msg: str,
     r: PrivateKey,
     C: PublicKey,
     e: PrivateKey,
     s: PrivateKey,
     A: PublicKey,
 ) -> bool:
-    Y: PublicKey = hash_to_curve_deprecated(secret_msg.encode("utf-8"))
+    Y: PublicKey = hash_to_curve_domain_separated(secret_msg.encode("utf-8"))
     C_: PublicKey = C + A.mult(r)  # type: ignore
     B_: PublicKey = Y + r.pubkey  # type: ignore
     valid = alice_verify_dleq(B_, C_, e, s, A)

cashu/core/settings.py

@@ -123,7 +123,7 @@ class WalletSettings(CashuSettings):
     mint_port: int = Field(default=3338)
     wallet_name: str = Field(default="wallet")
     wallet_unit: str = Field(default="sat")
-    wallet_use_deprecated_h2c: bool = Field(default=False)
+    wallet_domain_separation: bool = Field(default=False)
     api_port: int = Field(default=4448)
     api_host: str = Field(default="127.0.0.1")
 

cashu/wallet/wallet.py

@@ -998,11 +998,9 @@ async def pay_lightning(
         # NUT-08, the mint will imprint these outputs with a value depending on the
         # amount of fees we overpaid.
         n_change_outputs = calculate_number_of_blank_outputs(fee_reserve_sat)
-        (
-            change_secrets,
-            change_rs,
-            change_derivation_paths,
-        ) = await self.generate_n_secrets(n_change_outputs)
+        change_secrets, change_rs, change_derivation_paths = (
+            await self.generate_n_secrets(n_change_outputs)
+        )
         change_outputs, change_rs = self._construct_outputs(
             n_change_outputs * [1], change_secrets, change_rs
         )
@@ -1128,15 +1126,14 @@ async def _construct_proofs(
             C = b_dhke.step3_alice(
                 C_, r, self.keysets[promise.id].public_keys[promise.amount]
             )
-
-            if not settings.wallet_use_deprecated_h2c:
-                B_, r = b_dhke.step1_alice(secret, r)  # recompute B_ for dleq proofs
             # BEGIN: BACKWARDS COMPATIBILITY < 0.15.1
+            if not settings.wallet_domain_separation:
+                B_, r = b_dhke.step1_alice(secret, r)  # recompute B_ for dleq proofs
+            # END: BACKWARDS COMPATIBILITY < 0.15.1
             else:
-                B_, r = b_dhke.step1_alice_deprecated(
+                B_, r = b_dhke.step1_alice_domain_separated(
                     secret, r
                 )  # recompute B_ for dleq proofs
-            # END: BACKWARDS COMPATIBILITY < 0.15.1
 
             proof = Proof(
                 id=promise.id,
@@ -1199,13 +1196,12 @@ def _construct_outputs(
         rs_ = [None] * len(amounts) if not rs else rs
         rs_return: List[PrivateKey] = []
         for secret, amount, r in zip(secrets, amounts, rs_):
-            if not settings.wallet_use_deprecated_h2c:
-                B_, r = b_dhke.step1_alice(secret, r or None)
             # BEGIN: BACKWARDS COMPATIBILITY < 0.15.1
-            else:
-                B_, r = b_dhke.step1_alice_deprecated(secret, r or None)
+            if not settings.wallet_domain_separation:
+                B_, r = b_dhke.step1_alice(secret, r or None)
             # END: BACKWARDS COMPATIBILITY < 0.15.1
-
+            else:
+                B_, r = b_dhke.step1_alice_domain_separated(secret, r or None)
             rs_return.append(r)
             output = BlindedMessage(
                 amount=amount, B_=B_.serialize().hex(), id=self.keyset_id