From 026b2f52e631664a298fe524c2dbfad83d746020 Mon Sep 17 00:00:00 2001
From: Chih Cheng Liang <chihchengliang@gmail.com>
Date: Mon, 6 May 2019 16:17:30 +0800
Subject: [PATCH] fast-verification-of-multiple-bls-signatures

---
 py_ecc/bls/__init__.py |  1 +
 py_ecc/bls/api.py      | 49 ++++++++++++++++++++++++++++++++++++++++++
 py_ecc/bls/utils.py    |  2 +-
 tests/test_bls.py      | 37 +++++++++++++++++++++++++++++++
 4 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/py_ecc/bls/__init__.py b/py_ecc/bls/__init__.py
index f52c3de1..0710cedb 100644
--- a/py_ecc/bls/__init__.py
+++ b/py_ecc/bls/__init__.py
@@ -5,4 +5,5 @@
     sign,
     verify,
     verify_multiple,
+    verify_multiple_multiple,
 )
diff --git a/py_ecc/bls/api.py b/py_ecc/bls/api.py
index 6a07d1d8..668465d5 100644
--- a/py_ecc/bls/api.py
+++ b/py_ecc/bls/api.py
@@ -1,5 +1,6 @@
 from typing import (
     Sequence,
+    Tuple,
 )
 
 from eth_typing import (
@@ -31,6 +32,9 @@
     pubkey_to_G1,
     signature_to_G2,
 )
+from secrets import (
+    randbelow,
+)
 
 
 def sign(message_hash: Hash32,
@@ -109,3 +113,48 @@ def verify_multiple(pubkeys: Sequence[BLSPubkey],
         return final_exponentiation == FQ12.one()
     except (ValidationError, ValueError, AssertionError):
         return False
+
+
+def verify_multiple_multiple(
+        signatures: Sequence[BLSSignature],
+        pubkeys_and_messages: Tuple[Sequence[BLSPubkey], Sequence[Hash32]],
+        domain: int)-> bool:
+    if len(signatures) != len(pubkeys_and_messages):
+        raise ValidationError(
+            "len(signatures) (%s) should be equal to len(pubkeys_and_messages) (%s)" % (
+                len(signatures), len(pubkeys_and_messages)
+            )
+        )
+    try:
+        random_ints = tuple(2**randbelow(64) for _ in range(len(signatures)))
+        o = FQ12.one()
+        for index, pm in enumerate(pubkeys_and_messages):
+            pubkeys, message_hashes = pm  # type: ignore
+            len_msgs = len(message_hashes)
+            if len(pubkeys) != len_msgs:
+                raise ValidationError(
+                    "len(pubkeys) (%s) should be equal to len(message_hashes) (%s)" % (
+                        len(pubkeys), len_msgs
+                    )
+                )
+            for m_pubs in set(message_hashes):
+
+                # aggregate the pubs
+                group_pub = Z1
+                for i in range(len_msgs):
+                    if message_hashes[i] == m_pubs:
+                        group_pub = add(group_pub, pubkey_to_G1(pubkeys[i]))
+                o *= pairing(
+                    multiply(hash_to_G2(m_pubs, domain), random_ints[index]),
+                    group_pub,
+                    final_exponentiate=False,
+                )
+        agg_sig = Z2
+        for index, sig in enumerate(signatures):
+            agg_sig = add(agg_sig, multiply(signature_to_G2(sig), random_ints[index]))
+        o *= pairing(agg_sig, neg(G1), final_exponentiate=False)
+
+        final_exponentiation = final_exponentiate(o)
+        return final_exponentiation == FQ12.one()
+    except (ValidationError, ValueError, AssertionError):
+        return False
diff --git a/py_ecc/bls/utils.py b/py_ecc/bls/utils.py
index e8ad1658..5da0b4b4 100644
--- a/py_ecc/bls/utils.py
+++ b/py_ecc/bls/utils.py
@@ -146,7 +146,7 @@ def G1_to_pubkey(pt: G1Uncompressed) -> BLSPubkey:
 
 
 def pubkey_to_G1(pubkey: BLSPubkey) -> G1Uncompressed:
-    z = big_endian_to_int(pubkey)
+    z = G1Compressed(big_endian_to_int(pubkey))
     return decompress_G1(z)
 
 #
diff --git a/tests/test_bls.py b/tests/test_bls.py
index 94173736..aa24f159 100644
--- a/tests/test_bls.py
+++ b/tests/test_bls.py
@@ -10,6 +10,7 @@
     sign,
     verify,
     verify_multiple,
+    verify_multiple_multiple,
 )
 from py_ecc.bls.hash import (
     hash_eth2,
@@ -44,6 +45,7 @@
     normalize,
     field_modulus as q,
 )
+from random import sample
 
 
 @pytest.mark.parametrize(
@@ -238,3 +240,38 @@ def test_multi_aggregation(msg_1, msg_2, privkeys_1, privkeys_2):
         signature=aggsig,
         domain=domain,
     )
+
+
+def test_multi_multi():
+    domain = 0
+    validator_indices = tuple(range(10))
+    privkeys = tuple(2**i for i in validator_indices)
+    pubkeys = [privtopub(k) for k in privkeys]
+
+    class Attestation:
+        def __init__(self, msg_1, msg_2):
+            msg_1_validators = sample(validator_indices, 3)
+            msg_2_validators = sample(validator_indices, 3)
+            self.agg_pubkeys = [
+                aggregate_pubkeys([pubkeys[i] for i in msg_1_validators]),
+                aggregate_pubkeys([pubkeys[i] for i in msg_2_validators]),
+            ]
+            self.msgs = [msg_1, msg_2]
+            msg_1_sigs = [sign(msg_1, privkeys[i], domain) for i in msg_1_validators]
+            msg_2_sigs = [sign(msg_2, privkeys[i], domain) for i in msg_2_validators]
+            self.sig = aggregate_signatures([
+                aggregate_signatures(msg_1_sigs),
+                aggregate_signatures(msg_2_sigs),
+            ])
+
+    msgs = (
+        (b'\x12' * 32, b'\x34' * 32),
+        (b'\x56' * 32, b'\x78' * 32),
+        (b'\x90' * 32, b'\xab' * 32),
+    )
+    atts = [Attestation(msg_1, msg_2) for msg_1, msg_2 in msgs]
+    assert verify_multiple_multiple(
+        signatures=[att.sig for att in atts],
+        pubkeys_and_messages=[[att.agg_pubkeys, att.msgs] for att in atts],
+        domain=domain,
+    )