use byte strings for dictionary keys

Author: pipermerriam

ethereum/ethpow.py

@@ -114,9 +114,9 @@ def mine(block_number, difficulty, mining_hash, start_nonce=0, rounds=1000):
     for i in range(1, rounds + 1):
         bin_nonce = utils.zpad(utils.int_to_big_endian((nonce + i) & TT64M1), 8)
         o = hashimoto_light(block_number, cache, mining_hash, bin_nonce)
-        if o["result"] <= target:
+        if o[b"result"] <= target:
             log.debug("nonce found")
             assert len(bin_nonce) == 8
-            assert len(o["mix digest"]) == 32
-            return bin_nonce, o["mix digest"]
+            assert len(o[b"mix digest"]) == 32
+            return bin_nonce, o[b"mix digest"]
     return None, None