pyln-proto: Use only coincurve for libsecp256k1 bindings

secp256k1 Python library is not maintained anymore and coincurve was
already used in the `wire` module.

Changelog-None
Signed-off-by: Michal Rostecki <mrostecki@mailfence.com>

contrib/pyln-proto/pyln/proto/invoice.py

@@ -6,7 +6,7 @@ import base58
 import bitstring
 import hashlib
 import re
-import secp256k1
+import coincurve
 import time
 import struct
 
@@ -180,14 +180,14 @@ class Invoice(object):
 
     def __str__(self):
         return "Invoice[{}, amount={}{} tags=[{}]]".format(
-            hexlify(self.pubkey.serialize()).decode('utf-8'),
+            hexlify(self.pubkey.format()).decode('utf-8'),
             self.amount, self.currency,
             ", ".join([k + '=' + str(v) for k, v in self.tags])
         )
 
     @property
     def hexpubkey(self):
-        return hexlify(self.pubkey.serialize()).decode('ASCII')
+        return hexlify(self.pubkey.format()).decode('ASCII')
 
     @property
     def hexpaymenthash(self):
@@ -273,11 +273,8 @@ class Invoice(object):
             raise ValueError("Must include either 'd' or 'h'")
 
         # We actually sign the hrp, then data (padded to 8 bits with zeroes).
-        privkey = secp256k1.PrivateKey(bytes(unhexlify(privkey)))
-        sig = privkey.ecdsa_sign_recoverable(bytearray([ord(c) for c in hrp]) + data.tobytes())
-        # This doesn't actually serialize, but returns a pair of values :(
-        sig, recid = privkey.ecdsa_recoverable_serialize(sig)
-        data += bytes(sig) + bytes([recid])
+        privkey = coincurve.PrivateKey(secret=bytes(unhexlify(privkey)))
+        data += privkey.sign_recoverable(bytearray([ord(c) for c in hrp]) + data.tobytes())
 
         return bech32_encode(hrp, bitarray_to_u5(data))
 
@@ -374,8 +371,7 @@ class Invoice(object):
                 if data_length != 53:
                     inv.unknown_tags.append((tag, tagdata))
                     continue
-                inv.pubkey = secp256k1.PublicKey(flags=secp256k1.ALL_FLAGS)
-                inv.pubkey.deserialize(trim_to_bytes(tagdata))
+                inv.pubkey = coincurve.PublicKey(trim_to_bytes(tagdata))
 
             elif tag == 'c':
                 inv.min_final_cltv_expiry = tagdata.uint
@@ -395,11 +391,11 @@ class Invoice(object):
             if not inv.pubkey.ecdsa_verify(bytearray([ord(c) for c in hrp]) + data.tobytes(), inv.signature):
                 raise ValueError('Invalid signature')
         else:  # Recover pubkey from signature.
-            inv.pubkey = secp256k1.PublicKey(flags=secp256k1.ALL_FLAGS)
-            inv.signature = inv.pubkey.ecdsa_recoverable_deserialize(
-                sigdecoded[0:64], sigdecoded[64])
-            inv.pubkey.public_key = inv.pubkey.ecdsa_recover(
-                bytearray([ord(c) for c in hrp]) + data.tobytes(), inv.signature)
+            inv.signature = coincurve.ecdsa.deserialize_recoverable(
+                sigdecoded[0:65])
+            inv.pubkey = coincurve.PublicKey.from_signature_and_message(
+                sigdecoded[0:65],
+                bytearray([ord(c) for c in hrp]) + data.tobytes())
 
         return inv
 

contrib/pyln-proto/requirements.txt

@@ -2,4 +2,3 @@ bitstring==3.1.6
 cryptography==2.8
 coincurve==13.0.0
 base58==1.0.2
-secp256k1==0.13.2

contrib/pyln-proto/tests/test_invoice.py

@@ -1,6 +1,7 @@
 from pyln.proto import Invoice
 from decimal import Decimal
 from bitstring import ConstBitStream
+import binascii
 
 
 def test_decode():
@@ -13,3 +14,14 @@ def test_decode():
     assert(inv.amount == Decimal('0.000001'))
     assert(inv.featurebits == ConstBitStream('0x28200'))
     print(inv)
+
+
+def test_encode():
+    inv = Invoice(paymenthash=binascii.unhexlify("76272b9b95b14eb6bece3cd051006d8aabac63c3a50bd7ea2bb53612b0a9324b"),
+                  amount=Decimal('0.000001'),
+                  tags=[('d', 'test_pay_routeboost2'),
+                        ('x', 604800)],
+                  date=1579298293)
+    privkey = 'c28a9f80738f770d527803a566cf6fc3edf6cea586c4fc4a5223a5ad797e1ac3'
+    i = inv.encode(privkey)
+    assert(i == 'lnbc1u1p0zyt04pp5wcnjhxu4k98td0kw8ng9zqrd3246cc7r559a063tk5mp9v9fxf9sdpqw3jhxazlwpshjhmjda6hgetzdahhxapjxqyjw5q0s43wfg4f6yl200hc805kc9u97dp7m6j98fz33uzf4t6kp73trcz8fxkrpass063j2j4quxjr4th2r72lk27tm2aw383zgnl8zpgajsq5kmll8')