328: Add reference implementation

bip-0328/reference.py

@@ -0,0 +1,31 @@
+#! /usr/bin/env python3
+
+import json
+import os
+import sys
+
+from _base58 import xpub_to_pub_hex
+from _bip327 import cbytes, key_agg
+from _xpub import ExtendedKey
+
+CHAINCODE = bytes.fromhex("868087ca02a6f974c4598924c36b57762d32cb45717167e300622c7167e38965")
+
+def aggregate_to_xpub(aggregate: bytes) -> ExtendedKey:
+    return ExtendedKey(ExtendedKey.MAINNET_PUBLIC, 0, b"\x00\x00\x00\x00", 0, CHAINCODE, None, aggregate)
+
+def test_aggregate_to_xpub():
+    with open(os.path.join(sys.path[0], "vectors.json"), "r") as f:
+        test_data = json.load(f)
+
+    for test_case in test_data:
+        keys = [bytes.fromhex(k) for k in test_case["keys"]]
+
+        agg_ctx = key_agg(keys)
+        pub = cbytes(agg_ctx.Q)
+        assert pub.hex() == test_case["aggregate_pubkey"]
+
+        xpub = aggregate_to_xpub(pub)
+        assert xpub.to_string() == test_case["xpub"]
+
+if __name__ == "__main__":
+    test_aggregate_to_xpub()