From 519b3759535097a24910a125ab763e0aa817fbdd Mon Sep 17 00:00:00 2001
From: callebtc <93376500+callebtc@users.noreply.github.com>
Date: Sat, 5 Nov 2022 17:24:33 +0100
Subject: [PATCH] comments

---
 cashu/core/b_dhke.py | 9 +++++++--
 cashu/core/base.py   | 4 +++-
 cashu/core/legacy.py | 8 ++++++--
 cashu/mint/router.py | 4 +++-
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/cashu/core/b_dhke.py b/cashu/core/b_dhke.py
index 5c83ddc..8d0d6db 100644
--- a/cashu/core/b_dhke.py
+++ b/cashu/core/b_dhke.py
@@ -2,23 +2,28 @@
 
 """
 Implementation of https://gist.github.com/RubenSomsen/be7a4760dd4596d06963d67baf140406
-Alice:
+
+Alice (Client):
 A = a*G
 return A
-Bob:
+
+Bob (Mint):
 Y = hash_to_curve(secret_message)
 r = random blinding factor
 B'= Y + r*G
 return B'
+
 Alice:
 C' = a*B'
   (= a*Y + a*r*G)
 return C'
+
 Bob:
 C = C' - r*A
  (= C' - a*r*G)
  (= a*Y)
 return C, secret_message
+
 Alice:
 Y = hash_to_curve(secret_message)
 C == a*Y
diff --git a/cashu/core/base.py b/cashu/core/base.py
index 6e4989f..d39db5e 100644
--- a/cashu/core/base.py
+++ b/cashu/core/base.py
@@ -14,7 +14,9 @@ class P2SHScript(BaseModel):
 
 
 class Proof(BaseModel):
-    id: Union[None, str] = ""
+    id: Union[
+        None, str
+    ] = ""  # NOTE: None for backwards compatibility of old clients < 0.3
     amount: int = 0
     secret: str = ""
     C: str = ""
diff --git a/cashu/core/legacy.py b/cashu/core/legacy.py
index 6abd9c1..7434bdf 100644
--- a/cashu/core/legacy.py
+++ b/cashu/core/legacy.py
@@ -4,8 +4,12 @@ from secp256k1 import PublicKey
 
 
 def hash_to_point_pre_0_3_3(secret_msg):
-    """Generates x coordinate from the message hash and checks if the point lies on the curve.
-    If it does not, it tries computing again a new x coordinate from the hash of the coordinate."""
+    """
+    NOTE: Clients pre 0.3.3 used a different hash_to_curve
+
+    Generates x coordinate from the message hash and checks if the point lies on the curve.
+    If it does not, it tries computing again a new x coordinate from the hash of the coordinate.
+    """
     point = None
     msg = secret_msg
     while point is None:
diff --git a/cashu/mint/router.py b/cashu/mint/router.py
index db18cee..09ca2e2 100644
--- a/cashu/mint/router.py
+++ b/cashu/mint/router.py
@@ -104,8 +104,10 @@ async def split(
     """
     proofs = payload.proofs
     amount = payload.amount
+
+    # NOTE: backwards compatibility with clients < v0.2.2
     outputs = payload.outputs.blinded_messages if payload.outputs else None
-    # backwards compatibility with clients < v0.2.2
+
     assert outputs, Exception("no outputs provided.")
     try:
         split_return = await ledger.split(proofs, amount, outputs)