[qa] py2: Unfiddle strings into bytes explicitly

Github-Pull: #7853
Rebased-From: faa41ee204124da19dcf1e5b8a3aef1e216bf5e6, fa7abe0a00464e6aa88d55c63dba40878bbe5b79

 Conflicts:
	qa/rpc-tests/invalidtxrequest.py
	qa/rpc-tests/p2p-feefilter.py
	qa/rpc-tests/proxy_test.py
	qa/rpc-tests/test_framework/mininode.py
	qa/rpc-tests/test_framework/netutil.py
	src/test/bctest.py

26 files changed, 199 insertions, 209 deletions

diff --git a/qa/rpc-tests/bip65-cltv-p2p.py b/qa/rpc-tests/bip65-cltv-p2p.py
index b7ad03631b..5cb78e7a40 100755
--- a/qa/rpc-tests/bip65-cltv-p2p.py
+++ b/qa/rpc-tests/bip65-cltv-p2p.py
@@ -10,7 +10,6 @@ from test_framework.mininode import CTransaction, NetworkThread
 from test_framework.blocktools import create_coinbase, create_block
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import CScript, OP_1NEGATE, OP_CHECKLOCKTIMEVERIFY, OP_DROP
-from binascii import unhexlify
 from io import BytesIO
 import time
 
@@ -60,7 +59,7 @@ class BIP65Test(ComparisonTestFramework):
         rawtx = node.createrawtransaction(inputs, outputs)
         signresult = node.signrawtransaction(rawtx)
         tx = CTransaction()
-        f = BytesIO(unhexlify(signresult['hex']))
+        f = BytesIO(hex_str_to_bytes(signresult['hex']))
         tx.deserialize(f)
         return tx
 
diff --git a/qa/rpc-tests/bip68-112-113-p2p.py b/qa/rpc-tests/bip68-112-113-p2p.py
index f391cb0b7a..bcd44012f5 100755
--- a/qa/rpc-tests/bip68-112-113-p2p.py
+++ b/qa/rpc-tests/bip68-112-113-p2p.py
@@ -10,7 +10,6 @@ from test_framework.mininode import ToHex, CTransaction, NetworkThread
 from test_framework.blocktools import create_coinbase, create_block
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import *
-from binascii import unhexlify
 from io import BytesIO
 import time
 
@@ -119,7 +118,7 @@ class BIP68_112_113Test(ComparisonTestFramework):
         outputs = { to_address : amount }
         rawtx = node.createrawtransaction(inputs, outputs)
         tx = CTransaction()
-        f = BytesIO(unhexlify(rawtx))
+        f = BytesIO(hex_str_to_bytes(rawtx))
         tx.deserialize(f)
         return tx
 
@@ -127,7 +126,7 @@ class BIP68_112_113Test(ComparisonTestFramework):
         rawtx = ToHex(unsignedtx)
         signresult = node.signrawtransaction(rawtx)
         tx = CTransaction()
-        f = BytesIO(unhexlify(signresult['hex']))
+        f = BytesIO(hex_str_to_bytes(signresult['hex']))
         tx.deserialize(f)
         return tx
 
diff --git a/qa/rpc-tests/bip9-softforks.py b/qa/rpc-tests/bip9-softforks.py
index 98975e7193..d131eed92d 100755
--- a/qa/rpc-tests/bip9-softforks.py
+++ b/qa/rpc-tests/bip9-softforks.py
@@ -10,7 +10,6 @@ from test_framework.mininode import CTransaction, NetworkThread
 from test_framework.blocktools import create_coinbase, create_block
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import CScript, OP_1NEGATE, OP_NOP3, OP_DROP
-from binascii import hexlify, unhexlify
 from io import BytesIO
 import time
 import itertools
@@ -30,7 +29,6 @@ test that enforcement has triggered
 '''
 
 
-
 class BIP9SoftForksTest(ComparisonTestFramework):
 
     def __init__(self):
@@ -53,15 +51,15 @@ class BIP9SoftForksTest(ComparisonTestFramework):
         outputs = { to_address : amount }
         rawtx = node.createrawtransaction(inputs, outputs)
         tx = CTransaction()
-        f = BytesIO(unhexlify(rawtx))
+        f = BytesIO(hex_str_to_bytes(rawtx))
         tx.deserialize(f)
         tx.nVersion = 2
         return tx
 
     def sign_transaction(self, node, tx):
-        signresult = node.signrawtransaction(hexlify(tx.serialize()))
+        signresult = node.signrawtransaction(bytes_to_hex_str(tx.serialize()))
         tx = CTransaction()
-        f = BytesIO(unhexlify(signresult['hex']))
+        f = BytesIO(hex_str_to_bytes(signresult['hex']))
         tx.deserialize(f)
         return tx
 
@@ -184,7 +182,6 @@ class BIP9SoftForksTest(ComparisonTestFramework):
         NetworkThread().start() # Start up network handling in another thread
 
 
-
     def get_tests(self):
         for test in itertools.chain(
                 self.test_BIP('csv', 536870913, self.sequence_lock_invalidate, self.donothing),
diff --git a/qa/rpc-tests/bipdersig-p2p.py b/qa/rpc-tests/bipdersig-p2p.py
index 01b64871b8..b1db5ba4af 100755
--- a/qa/rpc-tests/bipdersig-p2p.py
+++ b/qa/rpc-tests/bipdersig-p2p.py
@@ -10,7 +10,6 @@ from test_framework.mininode import CTransaction, NetworkThread
 from test_framework.blocktools import create_coinbase, create_block
 from test_framework.comptool import TestInstance, TestManager
 from test_framework.script import CScript
-from binascii import unhexlify
 from io import BytesIO
 import time
 
@@ -25,7 +24,7 @@ def unDERify(tx):
     newscript = []
     for i in scriptSig:
         if (len(newscript) == 0):
-            newscript.append(i[0:-1] + '\0' + i[-1])
+            newscript.append(i[0:-1] + b'\0' + i[-1:])
         else:
             newscript.append(i)
     tx.vin[0].scriptSig = CScript(newscript)
@@ -68,7 +67,7 @@ class BIP66Test(ComparisonTestFramework):
         rawtx = node.createrawtransaction(inputs, outputs)
         signresult = node.signrawtransaction(rawtx)
         tx = CTransaction()
-        f = BytesIO(unhexlify(signresult['hex']))
+        f = BytesIO(hex_str_to_bytes(signresult['hex']))
         tx.deserialize(f)
         return tx
 
diff --git a/qa/rpc-tests/decodescript.py b/qa/rpc-tests/decodescript.py
index 2dfafac2fc..578844f2c5 100755
--- a/qa/rpc-tests/decodescript.py
+++ b/qa/rpc-tests/decodescript.py
@@ -6,7 +6,6 @@
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
 from test_framework.mininode import *
-from binascii import hexlify, unhexlify
 from io import BytesIO
 
 class DecodeScriptTest(BitcoinTestFramework):
@@ -131,7 +130,7 @@ class DecodeScriptTest(BitcoinTestFramework):
         assert_equal('OP_DUP OP_HASH160 dc863734a218bfe83ef770ee9d41a27f824a6e56 OP_EQUALVERIFY OP_CHECKSIG', rpc_result['vout'][0]['scriptPubKey']['asm'])
         assert_equal('OP_HASH160 2a5edea39971049a540474c6a99edf0aa4074c58 OP_EQUAL', rpc_result['vout'][1]['scriptPubKey']['asm'])
         txSave = CTransaction()
-        txSave.deserialize(BytesIO(unhexlify(tx)))
+        txSave.deserialize(BytesIO(hex_str_to_bytes(tx)))
 
         # make sure that a specifically crafted op_return value will not pass all the IsDERSignature checks and then get decoded as a sighash type
         tx = '01000000015ded05872fdbda629c7d3d02b194763ce3b9b1535ea884e3c8e765d42e316724020000006b48304502204c10d4064885c42638cbff3585915b322de33762598321145ba033fc796971e2022100bb153ad3baa8b757e30a2175bd32852d2e1cb9080f84d7e32fcdfd667934ef1b012103163c0ff73511ea1743fb5b98384a2ff09dd06949488028fd819f4d83f56264efffffffff0200000000000000000b6a0930060201000201000180380100000000001976a9141cabd296e753837c086da7a45a6c2fe0d49d7b7b88ac00000000'
@@ -147,7 +146,7 @@ class DecodeScriptTest(BitcoinTestFramework):
         # some more full transaction tests of varying specific scriptSigs. used instead of
         # tests in decodescript_script_sig because the decodescript RPC is specifically
         # for working on scriptPubKeys (argh!).
-        push_signature = hexlify(txSave.vin[0].scriptSig)[2:(0x48*2+4)]
+        push_signature = bytes_to_hex_str(txSave.vin[0].scriptSig)[2:(0x48*2+4)]
         signature = push_signature[2:]
         der_signature = signature[:-2]
         signature_sighash_decoded = der_signature + '[ALL]'
@@ -156,25 +155,24 @@ class DecodeScriptTest(BitcoinTestFramework):
         signature_2_sighash_decoded = der_signature + '[NONE|ANYONECANPAY]'
 
         # 1) P2PK scriptSig
-        txSave.vin[0].scriptSig = unhexlify(push_signature)
-        rpc_result = self.nodes[0].decoderawtransaction(hexlify(txSave.serialize()))
+        txSave.vin[0].scriptSig = hex_str_to_bytes(push_signature)
+        rpc_result = self.nodes[0].decoderawtransaction(bytes_to_hex_str(txSave.serialize()))
         assert_equal(signature_sighash_decoded, rpc_result['vin'][0]['scriptSig']['asm'])
 
         # make sure that the sighash decodes come out correctly for a more complex / lesser used case.
-        txSave.vin[0].scriptSig = unhexlify(push_signature_2)
-        rpc_result = self.nodes[0].decoderawtransaction(hexlify(txSave.serialize()))
+        txSave.vin[0].scriptSig = hex_str_to_bytes(push_signature_2)
+        rpc_result = self.nodes[0].decoderawtransaction(bytes_to_hex_str(txSave.serialize()))
         assert_equal(signature_2_sighash_decoded, rpc_result['vin'][0]['scriptSig']['asm'])
 
         # 2) multisig scriptSig
-        txSave.vin[0].scriptSig = unhexlify('00' + push_signature + push_signature_2)
-        rpc_result = self.nodes[0].decoderawtransaction(hexlify(txSave.serialize()))
+        txSave.vin[0].scriptSig = hex_str_to_bytes('00' + push_signature + push_signature_2)
+        rpc_result = self.nodes[0].decoderawtransaction(bytes_to_hex_str(txSave.serialize()))
         assert_equal('0 ' + signature_sighash_decoded + ' ' + signature_2_sighash_decoded, rpc_result['vin'][0]['scriptSig']['asm'])
 
         # 3) test a scriptSig that contains more than push operations.
         # in fact, it contains an OP_RETURN with data specially crafted to cause improper decode if the code does not catch it.
-        txSave.vin[0].scriptSig = unhexlify('6a143011020701010101010101020601010101010101')
-        rpc_result = self.nodes[0].decoderawtransaction(hexlify(txSave.serialize()))
-        print(hexlify('636174'))
+        txSave.vin[0].scriptSig = hex_str_to_bytes('6a143011020701010101010101020601010101010101')
+        rpc_result = self.nodes[0].decoderawtransaction(bytes_to_hex_str(txSave.serialize()))
         assert_equal('OP_RETURN 3011020701010101010101020601010101010101', rpc_result['vin'][0]['scriptSig']['asm'])
 
     def run_test(self):
diff --git a/qa/rpc-tests/fundrawtransaction.py b/qa/rpc-tests/fundrawtransaction.py
index 82c9e48a49..4492ea398f 100755
--- a/qa/rpc-tests/fundrawtransaction.py
+++ b/qa/rpc-tests/fundrawtransaction.py
@@ -148,7 +148,6 @@ class RawTransactionsTest(BitcoinTestFramework):
         assert_equal(fee + totalOut, utx['amount']) #compare vin total and totalout+fee
 
 
-
         #####################################################################
         # test a fundrawtransaction with which will not get a change output #
         #####################################################################
@@ -178,7 +177,6 @@ class RawTransactionsTest(BitcoinTestFramework):
         assert_equal(fee + totalOut, utx['amount']) #compare vin total and totalout+fee
 
 
-
         #########################################################################
         # test a fundrawtransaction with a VIN smaller than the required amount #
         #########################################################################
@@ -484,7 +482,6 @@ class RawTransactionsTest(BitcoinTestFramework):
         assert_equal(oldBalance+Decimal('51.10000000'), self.nodes[0].getbalance())
 
 
-
         ###############################################
         # multiple (~19) inputs tx test | Compare fee #
         ###############################################
diff --git a/qa/rpc-tests/getblocktemplate_proposals.py b/qa/rpc-tests/getblocktemplate_proposals.py
index d2cb4ab8d6..07bfe69c6d 100755
--- a/qa/rpc-tests/getblocktemplate_proposals.py
+++ b/qa/rpc-tests/getblocktemplate_proposals.py
@@ -130,7 +130,7 @@ class GetBlockTemplateProposalTest(BitcoinTestFramework):
 
         # Test 5: Add an invalid tx to the end (non-duplicate)
         txlist.append(bytearray(txlist[0]))
-        txlist[-1][4+1] = b'\xff'
+        txlist[-1][4+1] = 0xff
         assert_template(node, tmpl, txlist, 'bad-txns-inputs-missingorspent')
         txlist.pop()
 
diff --git a/qa/rpc-tests/httpbasics.py b/qa/rpc-tests/httpbasics.py
index c231676ec8..ce62fef46b 100755
--- a/qa/rpc-tests/httpbasics.py
+++ b/qa/rpc-tests/httpbasics.py
@@ -9,7 +9,6 @@
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
-import base64
 
 try:
     import http.client as httplib
@@ -31,7 +30,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         #################################################
         url = urlparse.urlparse(self.nodes[0].url)
         authpair = url.username + ':' + url.password
-        headers = {"Authorization": "Basic " + base64.b64encode(authpair)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpair)}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -48,7 +47,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         conn.close()
 
         #same should be if we add keep-alive because this should be the std. behaviour
-        headers = {"Authorization": "Basic " + base64.b64encode(authpair), "Connection": "keep-alive"}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpair), "Connection": "keep-alive"}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -65,7 +64,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         conn.close()
 
         #now do the same with "Connection: close"
-        headers = {"Authorization": "Basic " + base64.b64encode(authpair), "Connection":"close"}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpair), "Connection":"close"}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -77,7 +76,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         #node1 (2nd node) is running with disabled keep-alive option
         urlNode1 = urlparse.urlparse(self.nodes[1].url)
         authpair = urlNode1.username + ':' + urlNode1.password
-        headers = {"Authorization": "Basic " + base64.b64encode(authpair)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpair)}
 
         conn = httplib.HTTPConnection(urlNode1.hostname, urlNode1.port)
         conn.connect()
@@ -88,7 +87,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         #node2 (third node) is running with standard keep-alive parameters which means keep-alive is on
         urlNode2 = urlparse.urlparse(self.nodes[2].url)
         authpair = urlNode2.username + ':' + urlNode2.password
-        headers = {"Authorization": "Basic " + base64.b64encode(authpair)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpair)}
 
         conn = httplib.HTTPConnection(urlNode2.hostname, urlNode2.port)
         conn.connect()
diff --git a/qa/rpc-tests/invalidblockrequest.py b/qa/rpc-tests/invalidblockrequest.py
index 4b8edd380d..63fe5eae98 100755
--- a/qa/rpc-tests/invalidblockrequest.py
+++ b/qa/rpc-tests/invalidblockrequest.py
@@ -77,9 +77,9 @@ class InvalidBlockRequestTest(ComparisonTestFramework):
         block2 = create_block(self.tip, create_coinbase(height), self.block_time)
         self.block_time += 1
 
-        # chr(81) is OP_TRUE
-        tx1 = create_transaction(self.block1.vtx[0], 0, chr(81), 50 * COIN)
-        tx2 = create_transaction(tx1, 0, chr(81), 50 * COIN)
+        # b'0x51' is OP_TRUE
+        tx1 = create_transaction(self.block1.vtx[0], 0, b'\x51', 50 * COIN)
+        tx2 = create_transaction(tx1, 0, b'\x51', 50 * COIN)
 
         block2.vtx.extend([tx1, tx2])
         block2.hashMerkleRoot = block2.calc_merkle_root()
@@ -95,7 +95,7 @@ class InvalidBlockRequestTest(ComparisonTestFramework):
         assert(block2_orig.vtx != block2.vtx)
 
         self.tip = block2.sha256
-        yield TestInstance([[block2, RejectResult(16,'bad-txns-duplicate')], [block2_orig, True]])
+        yield TestInstance([[block2, RejectResult(16, b'bad-txns-duplicate')], [block2_orig, True]])
         height += 1
 
         '''
@@ -110,7 +110,7 @@ class InvalidBlockRequestTest(ComparisonTestFramework):
         block3.rehash()
         block3.solve()
 
-        yield TestInstance([[block3, RejectResult(16,'bad-cb-amount')]])
+        yield TestInstance([[block3, RejectResult(16, b'bad-cb-amount')]])
 
 
 if __name__ == '__main__':
diff --git a/qa/rpc-tests/invalidtxrequest.py b/qa/rpc-tests/invalidtxrequest.py
index 9834c85761..45ae78a48d 100755
--- a/qa/rpc-tests/invalidtxrequest.py
+++ b/qa/rpc-tests/invalidtxrequest.py
@@ -61,10 +61,10 @@ class InvalidTxRequestTest(ComparisonTestFramework):
             height += 1
         yield test
 
-        # chr(100) is OP_NOTIF
+        # b'\x64' is OP_NOTIF
         # Transaction will be rejected with code 16 (REJECT_INVALID)
-        tx1 = create_transaction(self.block1.vtx[0], 0, chr(100), 50*COIN)
-        yield TestInstance([[tx1, RejectResult(16, 'mandatory-script-verify-flag-failed')]])
+        tx1 = create_transaction(self.block1.vtx[0], 0, b'\x64', 50 * COIN)
+        yield TestInstance([[tx1, RejectResult(16, b'mandatory-script-verify-flag-failed')]])
 
         # TODO: test further transactions...
 
diff --git a/qa/rpc-tests/listtransactions.py b/qa/rpc-tests/listtransactions.py
index 40bf8565de..d0e0f25a13 100755
--- a/qa/rpc-tests/listtransactions.py
+++ b/qa/rpc-tests/listtransactions.py
@@ -9,11 +9,10 @@ from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
 from test_framework.mininode import CTransaction, COIN
 from io import BytesIO
-import binascii
 
 def txFromHex(hexstring):
     tx = CTransaction()
-    f = BytesIO(binascii.unhexlify(hexstring))
+    f = BytesIO(hex_str_to_bytes(hexstring))
     tx.deserialize(f)
     return tx
 
@@ -162,7 +161,7 @@ class ListTransactionsTest(BitcoinTestFramework):
         tx3 = self.nodes[0].createrawtransaction(inputs, outputs)
         tx3_modified = txFromHex(tx3)
         tx3_modified.vin[0].nSequence = 0
-        tx3 = binascii.hexlify(tx3_modified.serialize()).decode('utf-8')
+        tx3 = bytes_to_hex_str(tx3_modified.serialize())
         tx3_signed = self.nodes[0].signrawtransaction(tx3)['hex']
         txid_3 = self.nodes[0].sendrawtransaction(tx3_signed)
 
@@ -188,7 +187,7 @@ class ListTransactionsTest(BitcoinTestFramework):
         # Replace tx3, and check that tx4 becomes unknown
         tx3_b = tx3_modified
         tx3_b.vout[0].nValue -= int(Decimal("0.004") * COIN) # bump the fee
-        tx3_b = binascii.hexlify(tx3_b.serialize()).decode('utf-8')
+        tx3_b = bytes_to_hex_str(tx3_b.serialize())
         tx3_b_signed = self.nodes[0].signrawtransaction(tx3_b)['hex']
         txid_3b = self.nodes[0].sendrawtransaction(tx3_b_signed, True)
         assert(is_opt_in(self.nodes[0], txid_3b))
diff --git a/qa/rpc-tests/multi_rpc.py b/qa/rpc-tests/multi_rpc.py
index 2452b77319..afb18cf3da 100755
--- a/qa/rpc-tests/multi_rpc.py
+++ b/qa/rpc-tests/multi_rpc.py
@@ -53,7 +53,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         password2 = "8/F3uMDw4KSEbw96U3CA1C4X05dkHDN2BPFjTgZW4KI="
         authpairnew = "rt:"+password
 
-        headers = {"Authorization": "Basic " + base64.b64encode(authpair)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpair)}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -63,7 +63,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
         conn.close()
         
         #Use new authpair to confirm both work
-        headers = {"Authorization": "Basic " + base64.b64encode(authpairnew)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpairnew)}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -74,7 +74,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
 
         #Wrong login name with rt's password
         authpairnew = "rtwrong:"+password
-        headers = {"Authorization": "Basic " + base64.b64encode(authpairnew)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpairnew)}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -85,7 +85,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
 
         #Wrong password for rt
         authpairnew = "rt:"+password+"wrong"
-        headers = {"Authorization": "Basic " + base64.b64encode(authpairnew)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpairnew)}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -96,7 +96,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
 
         #Correct for rt2
         authpairnew = "rt2:"+password2
-        headers = {"Authorization": "Basic " + base64.b64encode(authpairnew)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpairnew)}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -107,7 +107,7 @@ class HTTPBasicsTest (BitcoinTestFramework):
 
         #Wrong password for rt2
         authpairnew = "rt2:"+password2+"wrong"
-        headers = {"Authorization": "Basic " + base64.b64encode(authpairnew)}
+        headers = {"Authorization": "Basic " + str_to_b64str(authpairnew)}
 
         conn = httplib.HTTPConnection(url.hostname, url.port)
         conn.connect()
@@ -117,6 +117,5 @@ class HTTPBasicsTest (BitcoinTestFramework):
         conn.close()
 
 
-
 if __name__ == '__main__':
     HTTPBasicsTest ().main ()
diff --git a/qa/rpc-tests/p2p-fullblocktest.py b/qa/rpc-tests/p2p-fullblocktest.py
index e03b35d89c..f3ed806053 100755
--- a/qa/rpc-tests/p2p-fullblocktest.py
+++ b/qa/rpc-tests/p2p-fullblocktest.py
@@ -34,7 +34,7 @@ class FullBlockTest(ComparisonTestFramework):
         self.num_nodes = 1
         self.block_heights = {}
         self.coinbase_key = CECKey()
-        self.coinbase_key.set_secretbytes(bytes("horsebattery"))
+        self.coinbase_key.set_secretbytes(b"horsebattery")
         self.coinbase_pubkey = self.coinbase_key.get_pubkey()
         self.block_time = int(time.time())+1
         self.tip = None
@@ -71,7 +71,7 @@ class FullBlockTest(ComparisonTestFramework):
         block = create_block(base_block_hash, coinbase, self.block_time)
         if (spend != None):
             tx = CTransaction()
-            tx.vin.append(CTxIn(COutPoint(spend.tx.sha256, spend.n), "", 0xffffffff))  # no signature yet
+            tx.vin.append(CTxIn(COutPoint(spend.tx.sha256, spend.n), b"", 0xffffffff))  # no signature yet
             # This copies the java comparison tool testing behavior: the first
             # txout has a garbage scriptPubKey, "to make sure we're not
             # pre-verifying too much" (?)
@@ -81,7 +81,7 @@ class FullBlockTest(ComparisonTestFramework):
             else:
                 tx.vout.append(CTxOut(1, script))
             # Now sign it if necessary
-            scriptSig = ""
+            scriptSig = b""
             scriptPubKey = bytearray(spend.tx.vout[spend.n].scriptPubKey)
             if (scriptPubKey[0] == OP_TRUE):  # looks like an anyone-can-spend
                 scriptSig = CScript([OP_TRUE])
@@ -226,7 +226,7 @@ class FullBlockTest(ComparisonTestFramework):
         #                      \-> b3 (1) -> b4 (2)
         tip(6)
         block(9, spend=out4, additional_coinbase_value=1)
-        yield rejected(RejectResult(16, 'bad-cb-amount'))
+        yield rejected(RejectResult(16, b'bad-cb-amount'))
 
         
         # Create a fork that ends in a block with too much fee (the one that causes the reorg)
@@ -238,7 +238,7 @@ class FullBlockTest(ComparisonTestFramework):
         yield rejected()
 
         block(11, spend=out4, additional_coinbase_value=1)
-        yield rejected(RejectResult(16, 'bad-cb-amount'))
+        yield rejected(RejectResult(16, b'bad-cb-amount'))
 
 
         # Try again, but with a valid fork first
@@ -280,7 +280,7 @@ class FullBlockTest(ComparisonTestFramework):
         out6 = get_spendable_output()
         too_many_checksigs = CScript([OP_CHECKSIG] * (1000000 // 50))
         block(16, spend=out6, script=too_many_checksigs)
-        yield rejected(RejectResult(16, 'bad-blk-sigops'))
+        yield rejected(RejectResult(16, b'bad-blk-sigops'))
 
 
         # Attempt to spend a transaction created on a different fork
@@ -289,7 +289,7 @@ class FullBlockTest(ComparisonTestFramework):
         #                      \-> b3 (1) -> b4 (2)
         tip(15)
         block(17, spend=txout_b3)
-        yield rejected(RejectResult(16, 'bad-txns-inputs-missingorspent'))
+        yield rejected(RejectResult(16, b'bad-txns-inputs-missingorspent'))
 
         # Attempt to spend a transaction created on a different fork (on a fork this time)
         #     genesis -> b1 (0) -> b2 (1) -> b5 (2) -> b6  (3)
@@ -310,7 +310,7 @@ class FullBlockTest(ComparisonTestFramework):
         tip(15)
         out7 = get_spendable_output()
         block(20, spend=out7)
-        yield rejected(RejectResult(16, 'bad-txns-premature-spend-of-coinbase'))
+        yield rejected(RejectResult(16, b'bad-txns-premature-spend-of-coinbase'))
 
         # Attempt to spend a coinbase at depth too low (on a fork this time)
         #     genesis -> b1 (0) -> b2 (1) -> b5 (2) -> b6  (3)
@@ -334,7 +334,7 @@ class FullBlockTest(ComparisonTestFramework):
         old_hash = b23.sha256
         tx = CTransaction()
         script_length = MAX_BLOCK_SIZE - len(b23.serialize()) - 69
-        script_output = CScript([chr(0)*script_length])
+        script_output = CScript([b'\x00' * script_length])
         tx.vout.append(CTxOut(0, script_output))
         tx.vin.append(CTxIn(COutPoint(b23.vtx[1].sha256, 1)))
         b23 = update_block(23, [tx])
@@ -346,11 +346,11 @@ class FullBlockTest(ComparisonTestFramework):
         tip(15)
         b24 = block(24, spend=out6)
         script_length = MAX_BLOCK_SIZE - len(b24.serialize()) - 69
-        script_output = CScript([chr(0)*(script_length+1)])
+        script_output = CScript([b'\x00' * (script_length+1)])
         tx.vout = [CTxOut(0, script_output)]
         b24 = update_block(24, [tx])
         assert_equal(len(b24.serialize()), MAX_BLOCK_SIZE+1)
-        yield rejected(RejectResult(16, 'bad-blk-length'))
+        yield rejected(RejectResult(16, b'bad-blk-length'))
 
         b25 = block(25, spend=out7)
         yield rejected()
@@ -362,12 +362,12 @@ class FullBlockTest(ComparisonTestFramework):
         #                      \-> b3 (1) -> b4 (2)
         tip(15)
         b26 = block(26, spend=out6)
-        b26.vtx[0].vin[0].scriptSig = chr(0)
+        b26.vtx[0].vin[0].scriptSig = b'\x00'
         b26.vtx[0].rehash()
         # update_block causes the merkle root to get updated, even with no new
         # transactions, and updates the required state.
         b26 = update_block(26, [])
-        yield rejected(RejectResult(16, 'bad-cb-length'))
+        yield rejected(RejectResult(16, b'bad-cb-length'))
 
         # Extend the b26 chain to make sure bitcoind isn't accepting b26
         b27 = block(27, spend=out7)
@@ -376,10 +376,10 @@ class FullBlockTest(ComparisonTestFramework):
         # Now try a too-large-coinbase script
         tip(15)
         b28 = block(28, spend=out6)
-        b28.vtx[0].vin[0].scriptSig = chr(0)*101
+        b28.vtx[0].vin[0].scriptSig = b'\x00' * 101
         b28.vtx[0].rehash()
         b28 = update_block(28, [])
-        yield rejected(RejectResult(16, 'bad-cb-length'))
+        yield rejected(RejectResult(16, b'bad-cb-length'))
 
         # Extend the b28 chain to make sure bitcoind isn't accepted b28
         b29 = block(29, spend=out7)
@@ -391,7 +391,7 @@ class FullBlockTest(ComparisonTestFramework):
         # b30 has a max-sized coinbase scriptSig.
         tip(23)
         b30 = block(30)
-        b30.vtx[0].vin[0].scriptSig = chr(0)*100
+        b30.vtx[0].vin[0].scriptSig = b'\x00' * 100
         b30.vtx[0].rehash()
         b30 = update_block(30, [])
         yield accepted()
diff --git a/qa/rpc-tests/proxy_test.py b/qa/rpc-tests/proxy_test.py
index 7f77e664d2..e94111ac79 100755
--- a/qa/rpc-tests/proxy_test.py
+++ b/qa/rpc-tests/proxy_test.py
@@ -77,7 +77,7 @@ class ProxyTest(BitcoinTestFramework):
         assert(isinstance(cmd, Socks5Command))
         # Note: bitcoind's SOCKS5 implementation only sends atyp DOMAINNAME, even if connecting directly to IPv4/IPv6
         assert_equal(cmd.atyp, AddressType.DOMAINNAME)
-        assert_equal(cmd.addr, "15.61.23.23")
+        assert_equal(cmd.addr, b"15.61.23.23")
         assert_equal(cmd.port, 1234)
         if not auth:
             assert_equal(cmd.username, None)
@@ -90,7 +90,7 @@ class ProxyTest(BitcoinTestFramework):
         assert(isinstance(cmd, Socks5Command))
         # Note: bitcoind's SOCKS5 implementation only sends atyp DOMAINNAME, even if connecting directly to IPv4/IPv6
         assert_equal(cmd.atyp, AddressType.DOMAINNAME)
-        assert_equal(cmd.addr, "1233:3432:2434:2343:3234:2345:6546:4534")
+        assert_equal(cmd.addr, b"1233:3432:2434:2343:3234:2345:6546:4534")
         assert_equal(cmd.port, 5443)
         if not auth:
             assert_equal(cmd.username, None)
@@ -103,7 +103,7 @@ class ProxyTest(BitcoinTestFramework):
             cmd = proxies[2].queue.get()
             assert(isinstance(cmd, Socks5Command))
             assert_equal(cmd.atyp, AddressType.DOMAINNAME)
-            assert_equal(cmd.addr, "bitcoinostk4e4re.onion")
+            assert_equal(cmd.addr, b"bitcoinostk4e4re.onion")
             assert_equal(cmd.port, 8333)
             if not auth:
                 assert_equal(cmd.username, None)
@@ -115,7 +115,7 @@ class ProxyTest(BitcoinTestFramework):
         cmd = proxies[3].queue.get()
         assert(isinstance(cmd, Socks5Command))
         assert_equal(cmd.atyp, AddressType.DOMAINNAME)
-        assert_equal(cmd.addr, "node.noumenon")
+        assert_equal(cmd.addr, b"node.noumenon")
         assert_equal(cmd.port, 8333)
         if not auth:
             assert_equal(cmd.username, None)
diff --git a/qa/rpc-tests/pruning.py b/qa/rpc-tests/pruning.py
index dd2adea950..eccd157e5c 100755
--- a/qa/rpc-tests/pruning.py
+++ b/qa/rpc-tests/pruning.py
@@ -311,7 +311,7 @@ class PruneTest(BitcoinTestFramework):
         #                   \                 \
         #                    ++...++(1044)     ..
         #
-        # N0    ********************(1032) @@...@@@(1552) 
+        # N0    ********************(1032) @@...@@@(1552)
         #                                 \
         #                                  *...**(1320)
 
diff --git a/qa/rpc-tests/rawtransactions.py b/qa/rpc-tests/rawtransactions.py
index 9f660c8bda..b76cc1f580 100755
--- a/qa/rpc-tests/rawtransactions.py
+++ b/qa/rpc-tests/rawtransactions.py
@@ -88,8 +88,6 @@ class RawTransactionsTest(BitcoinTestFramework):
         assert_equal(self.nodes[2].getbalance(), bal+Decimal('1.20000000')) #node2 has both keys of the 2of2 ms addr., tx should affect the balance
 
 
-
-
         # 2of3 test from different nodes
         bal = self.nodes[2].getbalance()
         addr1 = self.nodes[1].getnewaddress()
diff --git a/qa/rpc-tests/replace-by-fee.py b/qa/rpc-tests/replace-by-fee.py
index b951900c4d..4c8ef6de26 100755
--- a/qa/rpc-tests/replace-by-fee.py
+++ b/qa/rpc-tests/replace-by-fee.py
@@ -11,15 +11,11 @@ from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
 from test_framework.script import *
 from test_framework.mininode import *
-import binascii
 
 MAX_REPLACEMENT_LIMIT = 100
 
-def satoshi_round(amount):
-    return Decimal(amount).quantize(Decimal('0.00000001'), rounding=ROUND_DOWN)
-
 def txToHex(tx):
-    return binascii.hexlify(tx.serialize()).decode('utf-8')
+    return bytes_to_hex_str(tx.serialize())
 
 def make_utxo(node, amount, confirmed=True, scriptPubKey=CScript([1])):
     """Create a txout with a given amount and scriptPubKey
@@ -53,9 +49,7 @@ def make_utxo(node, amount, confirmed=True, scriptPubKey=CScript([1])):
     tx2.vout = [CTxOut(amount, scriptPubKey)]
     tx2.rehash()
 
-    binascii.hexlify(tx2.serialize()).decode('utf-8')
-
-    signed_tx = node.signrawtransaction(binascii.hexlify(tx2.serialize()).decode('utf-8'))
+    signed_tx = node.signrawtransaction(txToHex(tx2))
 
     txid = node.sendrawtransaction(signed_tx['hex'], True)
 
diff --git a/qa/rpc-tests/rest.py b/qa/rpc-tests/rest.py
index 3c8a405bdd..359f9239fb 100755
--- a/qa/rpc-tests/rest.py
+++ b/qa/rpc-tests/rest.py
@@ -39,7 +39,7 @@ def http_get_call(host, port, path, response_object = 0):
     if response_object:
         return conn.getresponse()
 
-    return conn.getresponse().read()
+    return conn.getresponse().read().decode('utf-8')
 
 #allows simple http post calls with a request body
 def http_post_call(host, port, path, requestdata = '', response_object = 0):
@@ -141,9 +141,9 @@ class RESTTest (BitcoinTestFramework):
         bb_hash = self.nodes[0].getbestblockhash()
 
         binaryRequest = b'\x01\x02'
-        binaryRequest += binascii.unhexlify(txid)
+        binaryRequest += hex_str_to_bytes(txid)
         binaryRequest += pack("i", n)
-        binaryRequest += binascii.unhexlify(vintx)
+        binaryRequest += hex_str_to_bytes(vintx)
         binaryRequest += pack("i", 0)
 
         bin_response = http_post_call(url.hostname, url.port, '/rest/getutxos'+self.FORMAT_SEPARATOR+'bin', binaryRequest)
@@ -234,7 +234,7 @@ class RESTTest (BitcoinTestFramework):
         assert_equal(response_hex.status, 200)
         assert_greater_than(int(response_hex.getheader('content-length')), 160)
         response_hex_str = response_hex.read()
-        assert_equal(encode(response_str, "hex")[0:160], response_hex_str[0:160])
+        assert_equal(encode(response_str, "hex_codec")[0:160], response_hex_str[0:160])
 
         # compare with hex block header
         response_header_hex = http_get_call(url.hostname, url.port, '/rest/headers/1/'+bb_hash+self.FORMAT_SEPARATOR+"hex", True)
@@ -242,7 +242,7 @@ class RESTTest (BitcoinTestFramework):
         assert_greater_than(int(response_header_hex.getheader('content-length')), 160)
         response_header_hex_str = response_header_hex.read()
         assert_equal(response_hex_str[0:160], response_header_hex_str[0:160])
-        assert_equal(encode(response_header_str, "hex")[0:160], response_header_hex_str[0:160])
+        assert_equal(encode(response_header_str, "hex_codec")[0:160], response_header_hex_str[0:160])
 
         # check json format
         block_json_string = http_get_call(url.hostname, url.port, '/rest/block/'+bb_hash+self.FORMAT_SEPARATOR+'json')
@@ -252,7 +252,7 @@ class RESTTest (BitcoinTestFramework):
         # compare with json block header
         response_header_json = http_get_call(url.hostname, url.port, '/rest/headers/1/'+bb_hash+self.FORMAT_SEPARATOR+"json", True)
         assert_equal(response_header_json.status, 200)
-        response_header_json_str = response_header_json.read()
+        response_header_json_str = response_header_json.read().decode('utf-8')
         json_obj = json.loads(response_header_json_str, parse_float=Decimal)
         assert_equal(len(json_obj), 1) #ensure that there is one header in the json response
         assert_equal(json_obj[0]['hash'], bb_hash) #request/response hash should be the same
@@ -276,7 +276,7 @@ class RESTTest (BitcoinTestFramework):
         self.sync_all()
         response_header_json = http_get_call(url.hostname, url.port, '/rest/headers/5/'+bb_hash+self.FORMAT_SEPARATOR+"json", True)
         assert_equal(response_header_json.status, 200)
-        response_header_json_str = response_header_json.read()
+        response_header_json_str = response_header_json.read().decode('utf-8')
         json_obj = json.loads(response_header_json_str)
         assert_equal(len(json_obj), 5) #now we should have 5 header objects
 
@@ -292,7 +292,6 @@ class RESTTest (BitcoinTestFramework):
         assert_greater_than(int(response.getheader('content-length')), 10)
 
 
-
         # check block tx details
         # let's make 3 tx and mine them on node 1
         txs = []
diff --git a/qa/rpc-tests/test_framework/blocktools.py b/qa/rpc-tests/test_framework/blocktools.py
index 50c2a3214a..f8861c6274 100644
--- a/qa/rpc-tests/test_framework/blocktools.py
+++ b/qa/rpc-tests/test_framework/blocktools.py
@@ -62,6 +62,6 @@ def create_transaction(prevtx, n, sig, value):
     tx = CTransaction()
     assert(n < len(prevtx.vout))
     tx.vin.append(CTxIn(COutPoint(prevtx.sha256, n), sig, 0xffffffff))
-    tx.vout.append(CTxOut(value, ""))
+    tx.vout.append(CTxOut(value, b""))
     tx.calc_sha256()
     return tx
diff --git a/qa/rpc-tests/test_framework/comptool.py b/qa/rpc-tests/test_framework/comptool.py
index bb9fccb140..74aabdd01b 100755
--- a/qa/rpc-tests/test_framework/comptool.py
+++ b/qa/rpc-tests/test_framework/comptool.py
@@ -45,7 +45,7 @@ class RejectResult(object):
     '''
     Outcome that expects rejection of a transaction or block.
     '''
-    def __init__(self, code, reason=''):
+    def __init__(self, code, reason=b''):
         self.code = code
         self.reason = reason
     def match(self, other):
@@ -111,9 +111,9 @@ class TestNode(NodeConnCB):
             raise AssertionError("Got pong for unknown ping [%s]" % repr(message))
 
     def on_reject(self, conn, message):
-        if message.message == 'tx':
+        if message.message == b'tx':
             self.tx_reject_map[message.data] = RejectResult(message.code, message.reason)
-        if message.message == 'block':
+        if message.message == b'block':
             self.block_reject_map[message.data] = RejectResult(message.code, message.reason)
 
     def send_inv(self, obj):
diff --git a/qa/rpc-tests/test_framework/mininode.py b/qa/rpc-tests/test_framework/mininode.py
index f55bd72353..3198620ca2 100755
--- a/qa/rpc-tests/test_framework/mininode.py
+++ b/qa/rpc-tests/test_framework/mininode.py
@@ -20,10 +20,10 @@
 import struct
 import socket
 import asyncore
-import binascii
 import time
 import sys
 import random
+from binascii import hexlify, unhexlify
 from io import BytesIO
 from codecs import encode
 import hashlib
@@ -34,7 +34,7 @@ import copy
 
 BIP0031_VERSION = 60000
 MY_VERSION = 60001  # past bip-31 for ping/pong
-MY_SUBVERSION = "/python-mininode-tester:0.0.1/"
+MY_SUBVERSION = b"/python-mininode-tester:0.0.2/"
 
 MAX_INV_SZ = 50000
 MAX_BLOCK_SIZE = 1000000
@@ -131,7 +131,7 @@ def deser_vector(f, c):
 
 
 def ser_vector(l):
-    r = ""
+    r = b""
     if len(l) < 253:
         r = struct.pack("B", len(l))
     elif len(l) < 0x10000:
@@ -161,7 +161,7 @@ def deser_uint256_vector(f):
 
 
 def ser_uint256_vector(l):
-    r = ""
+    r = b""
     if len(l) < 253:
         r = struct.pack("B", len(l))
     elif len(l) < 0x10000:
@@ -221,7 +221,7 @@ def deser_int_vector(f):
 
 
 def ser_int_vector(l):
-    r = ""
+    r = b""
     if len(l) < 253:
         r = struct.pack("B", len(l))
     elif len(l) < 0x10000:
@@ -236,19 +236,19 @@ def ser_int_vector(l):
 
 # Deserialize from a hex string representation (eg from RPC)
 def FromHex(obj, hex_string):
-    obj.deserialize(BytesIO(binascii.unhexlify(hex_string)))
+    obj.deserialize(BytesIO(unhexlify(hex_string.encode('ascii'))))
     return obj
 
 # Convert a binary-serializable object to hex (eg for submission via RPC)
 def ToHex(obj):
-    return binascii.hexlify(obj.serialize()).decode('utf-8')
+    return hexlify(obj.serialize()).decode('ascii')
 
 # Objects that map to bitcoind objects, which can be serialized/deserialized
 
 class CAddress(object):
     def __init__(self):
         self.nServices = 1
-        self.pchReserved = "\x00" * 10 + "\xff" * 2
+        self.pchReserved = b"\x00" * 10 + b"\xff" * 2
         self.ip = "0.0.0.0"
         self.port = 0
 
@@ -259,7 +259,7 @@ class CAddress(object):
         self.port = struct.unpack(">H", f.read(2))[0]
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<Q", self.nServices)
         r += self.pchReserved
         r += socket.inet_aton(self.ip)
@@ -286,7 +286,7 @@ class CInv(object):
         self.hash = deser_uint256(f)
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<i", self.type)
         r += ser_uint256(self.hash)
         return r
@@ -306,7 +306,7 @@ class CBlockLocator(object):
         self.vHave = deser_uint256_vector(f)
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<i", self.nVersion)
         r += ser_uint256_vector(self.vHave)
         return r
@@ -326,7 +326,7 @@ class COutPoint(object):
         self.n = struct.unpack("<I", f.read(4))[0]
 
     def serialize(self):
-        r = ""
+        r = b""
         r += ser_uint256(self.hash)
         r += struct.pack("<I", self.n)
         return r
@@ -336,7 +336,7 @@ class COutPoint(object):
 
 
 class CTxIn(object):
-    def __init__(self, outpoint=None, scriptSig="", nSequence=0):
+    def __init__(self, outpoint=None, scriptSig=b"", nSequence=0):
         if outpoint is None:
             self.prevout = COutPoint()
         else:
@@ -351,7 +351,7 @@ class CTxIn(object):
         self.nSequence = struct.unpack("<I", f.read(4))[0]
 
     def serialize(self):
-        r = ""
+        r = b""
         r += self.prevout.serialize()
         r += ser_string(self.scriptSig)
         r += struct.pack("<I", self.nSequence)
@@ -359,12 +359,12 @@ class CTxIn(object):
 
     def __repr__(self):
         return "CTxIn(prevout=%s scriptSig=%s nSequence=%i)" \
-            % (repr(self.prevout), binascii.hexlify(self.scriptSig),
+            % (repr(self.prevout), hexlify(self.scriptSig),
                self.nSequence)
 
 
 class CTxOut(object):
-    def __init__(self, nValue=0, scriptPubKey=""):
+    def __init__(self, nValue=0, scriptPubKey=b""):
         self.nValue = nValue
         self.scriptPubKey = scriptPubKey
 
@@ -373,7 +373,7 @@ class CTxOut(object):
         self.scriptPubKey = deser_string(f)
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<q", self.nValue)
         r += ser_string(self.scriptPubKey)
         return r
@@ -381,7 +381,7 @@ class CTxOut(object):
     def __repr__(self):
         return "CTxOut(nValue=%i.%08i scriptPubKey=%s)" \
             % (self.nValue // COIN, self.nValue % COIN,
-               binascii.hexlify(self.scriptPubKey))
+               hexlify(self.scriptPubKey))
 
 
 class CTransaction(object):
@@ -410,7 +410,7 @@ class CTransaction(object):
         self.hash = None
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<i", self.nVersion)
         r += ser_vector(self.vin)
         r += ser_vector(self.vout)
@@ -424,7 +424,7 @@ class CTransaction(object):
     def calc_sha256(self):
         if self.sha256 is None:
             self.sha256 = uint256_from_str(hash256(self.serialize()))
-        self.hash = encode(hash256(self.serialize())[::-1], 'hex')
+        self.hash = encode(hash256(self.serialize())[::-1], 'hex_codec').decode('ascii')
 
     def is_valid(self):
         self.calc_sha256()
@@ -474,7 +474,7 @@ class CBlockHeader(object):
         self.hash = None
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<i", self.nVersion)
         r += ser_uint256(self.hashPrevBlock)
         r += ser_uint256(self.hashMerkleRoot)
@@ -485,7 +485,7 @@ class CBlockHeader(object):
 
     def calc_sha256(self):
         if self.sha256 is None:
-            r = ""
+            r = b""
             r += struct.pack("<i", self.nVersion)
             r += ser_uint256(self.hashPrevBlock)
             r += ser_uint256(self.hashMerkleRoot)
@@ -493,7 +493,7 @@ class CBlockHeader(object):
             r += struct.pack("<I", self.nBits)
             r += struct.pack("<I", self.nNonce)
             self.sha256 = uint256_from_str(hash256(r))
-            self.hash = encode(hash256(r)[::-1], 'hex')
+            self.hash = encode(hash256(r)[::-1], 'hex_codec').decode('ascii')
 
     def rehash(self):
         self.sha256 = None
@@ -516,7 +516,7 @@ class CBlock(CBlockHeader):
         self.vtx = deser_vector(f, CTransaction)
 
     def serialize(self):
-        r = ""
+        r = b""
         r += super(CBlock, self).serialize()
         r += ser_vector(self.vtx)
         return r
@@ -571,9 +571,9 @@ class CUnsignedAlert(object):
         self.nMaxVer = 0
         self.setSubVer = []
         self.nPriority = 0
-        self.strComment = ""
-        self.strStatusBar = ""
-        self.strReserved = ""
+        self.strComment = b""
+        self.strStatusBar = b""
+        self.strReserved = b""
 
     def deserialize(self, f):
         self.nVersion = struct.unpack("<i", f.read(4))[0]
@@ -591,7 +591,7 @@ class CUnsignedAlert(object):
         self.strReserved = deser_string(f)
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<i", self.nVersion)
         r += struct.pack("<q", self.nRelayUntil)
         r += struct.pack("<q", self.nExpiration)
@@ -616,8 +616,8 @@ class CUnsignedAlert(object):
 
 class CAlert(object):
     def __init__(self):
-        self.vchMsg = ""
-        self.vchSig = ""
+        self.vchMsg = b""
+        self.vchSig = b""
 
     def deserialize(self, f):
         self.vchMsg = deser_string(f)
@@ -636,7 +636,7 @@ class CAlert(object):
 
 # Objects that correspond to messages on the wire
 class msg_version(object):
-    command = "version"
+    command = b"version"
 
     def __init__(self):
         self.nVersion = MY_VERSION
@@ -672,7 +672,7 @@ class msg_version(object):
             self.nStartingHeight = None
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<i", self.nVersion)
         r += struct.pack("<Q", self.nServices)
         r += struct.pack("<q", self.nTime)
@@ -691,7 +691,7 @@ class msg_version(object):
 
 
 class msg_verack(object):
-    command = "verack"
+    command = b"verack"
 
     def __init__(self):
         pass
@@ -700,14 +700,14 @@ class msg_verack(object):
         pass
 
     def serialize(self):
-        return ""
+        return b""
 
     def __repr__(self):
         return "msg_verack()"
 
 
 class msg_addr(object):
-    command = "addr"
+    command = b"addr"
 
     def __init__(self):
         self.addrs = []
@@ -723,7 +723,7 @@ class msg_addr(object):
 
 
 class msg_alert(object):
-    command = "alert"
+    command = b"alert"
 
     def __init__(self):
         self.alert = CAlert()
@@ -733,7 +733,7 @@ class msg_alert(object):
         self.alert.deserialize(f)
 
     def serialize(self):
-        r = ""
+        r = b""
         r += self.alert.serialize()
         return r
 
@@ -742,7 +742,7 @@ class msg_alert(object):
 
 
 class msg_inv(object):
-    command = "inv"
+    command = b"inv"
 
     def __init__(self, inv=None):
         if inv is None:
@@ -761,7 +761,7 @@ class msg_inv(object):
 
 
 class msg_getdata(object):
-    command = "getdata"
+    command = b"getdata"
 
     def __init__(self, inv=None):
         self.inv = inv if inv != None else []
@@ -777,7 +777,7 @@ class msg_getdata(object):
 
 
 class msg_getblocks(object):
-    command = "getblocks"
+    command = b"getblocks"
 
     def __init__(self):
         self.locator = CBlockLocator()
@@ -789,7 +789,7 @@ class msg_getblocks(object):
         self.hashstop = deser_uint256(f)
 
     def serialize(self):
-        r = ""
+        r = b""
         r += self.locator.serialize()
         r += ser_uint256(self.hashstop)
         return r
@@ -800,7 +800,7 @@ class msg_getblocks(object):
 
 
 class msg_tx(object):
-    command = "tx"
+    command = b"tx"
 
     def __init__(self, tx=CTransaction()):
         self.tx = tx
@@ -816,7 +816,7 @@ class msg_tx(object):
 
 
 class msg_block(object):
-    command = "block"
+    command = b"block"
 
     def __init__(self, block=None):
         if block is None:
@@ -835,7 +835,7 @@ class msg_block(object):
 
 
 class msg_getaddr(object):
-    command = "getaddr"
+    command = b"getaddr"
 
     def __init__(self):
         pass
@@ -844,14 +844,14 @@ class msg_getaddr(object):
         pass
 
     def serialize(self):
-        return ""
+        return b""
 
     def __repr__(self):
         return "msg_getaddr()"
 
 
 class msg_ping_prebip31(object):
-    command = "ping"
+    command = b"ping"
 
     def __init__(self):
         pass
@@ -860,14 +860,14 @@ class msg_ping_prebip31(object):
         pass
 
     def serialize(self):
-        return ""
+        return b""
 
     def __repr__(self):
         return "msg_ping() (pre-bip31)"
 
 
 class msg_ping(object):
-    command = "ping"
+    command = b"ping"
 
     def __init__(self, nonce=0L):
         self.nonce = nonce
@@ -876,7 +876,7 @@ class msg_ping(object):
         self.nonce = struct.unpack("<Q", f.read(8))[0]
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<Q", self.nonce)
         return r
 
@@ -885,16 +885,16 @@ class msg_ping(object):
 
 
 class msg_pong(object):
-    command = "pong"
+    command = b"pong"
 
-    def __init__(self, nonce=0L):
+    def __init__(self, nonce=0):
         self.nonce = nonce
 
     def deserialize(self, f):
         self.nonce = struct.unpack("<Q", f.read(8))[0]
 
     def serialize(self):
-        r = ""
+        r = b""
         r += struct.pack("<Q", self.nonce)
         return r
 
@@ -903,7 +903,7 @@ class msg_pong(object):
 
 
 class msg_mempool(object):
-    command = "mempool"
+    command = b"mempool"
 
     def __init__(self):
         pass
@@ -912,13 +912,13 @@ class msg_mempool(object):
         pass
 
     def serialize(self):
-        return ""
+        return b""
 
     def __repr__(self):
         return "msg_mempool()"
 
 class msg_sendheaders(object):
-    command = "sendheaders"
+    command = b"sendheaders"
 
     def __init__(self):
         pass
@@ -927,7 +927,7 @@ class msg_sendheaders(object):
         pass
 
     def serialize(self):
-        return ""
+        return b""
 
     def __repr__(self):
         return "msg_sendheaders()"
@@ -937,7 +937,7 @@ class msg_sendheaders(object):
 # vector of hashes
 # hash_stop (hash of last desired block header, 0 to get as many as possible)
 class msg_getheaders(object):
-    command = "getheaders"
+    command = b"getheaders"
 
     def __init__(self):
         self.locator = CBlockLocator()
@@ -949,7 +949,7 @@ class msg_getheaders(object):
         self.hashstop = deser_uint256(f)
 
     def serialize(self):
-        r = ""
+        r = b""
         r += self.locator.serialize()
         r += ser_uint256(self.hashstop)
         return r
@@ -962,7 +962,7 @@ class msg_getheaders(object):
 # headers message has
 # <count> <vector of block headers>
 class msg_headers(object):
-    command = "headers"
+    command = b"headers"
 
     def __init__(self):
         self.headers = []
@@ -982,10 +982,10 @@ class msg_headers(object):
 
 
 class msg_reject(object):
-    command = "reject"
+    command = b"reject"
 
     def __init__(self):
-        self.message = ""
+        self.message = b""
         self.code = 0
         self.reason = ""
         self.data = 0L
@@ -1009,7 +1009,6 @@ class msg_reject(object):
         return "msg_reject: %s %d %s [%064x]" \
             % (self.message, self.code, self.reason, self.data)
 
-
 # This is what a callback should look like for NodeConn
 # Reimplement the on_* functions to provide handling for events
 class NodeConnCB(object):
@@ -1091,27 +1090,27 @@ class NodeConnCB(object):
 # This class provides an interface for a p2p connection to a specified node
 class NodeConn(asyncore.dispatcher):
     messagemap = {
-        "version": msg_version,
-        "verack": msg_verack,
-        "addr": msg_addr,
-        "alert": msg_alert,
-        "inv": msg_inv,
-        "getdata": msg_getdata,
-        "getblocks": msg_getblocks,
-        "tx": msg_tx,
-        "block": msg_block,
-        "getaddr": msg_getaddr,
-        "ping": msg_ping,
-        "pong": msg_pong,
-        "headers": msg_headers,
-        "getheaders": msg_getheaders,
-        "reject": msg_reject,
-        "mempool": msg_mempool
+        b"version": msg_version,
+        b"verack": msg_verack,
+        b"addr": msg_addr,
+        b"alert": msg_alert,
+        b"inv": msg_inv,
+        b"getdata": msg_getdata,
+        b"getblocks": msg_getblocks,
+        b"tx": msg_tx,
+        b"block": msg_block,
+        b"getaddr": msg_getaddr,
+        b"ping": msg_ping,
+        b"pong": msg_pong,
+        b"headers": msg_headers,
+        b"getheaders": msg_getheaders,
+        b"reject": msg_reject,
+        b"mempool": msg_mempool,
     }
     MAGIC_BYTES = {
-        "mainnet": "\xf9\xbe\xb4\xd9",   # mainnet
-        "testnet3": "\x0b\x11\x09\x07",  # testnet3
-        "regtest": "\xfa\xbf\xb5\xda"    # regtest
+        "mainnet": b"\xf9\xbe\xb4\xd9",   # mainnet
+        "testnet3": b"\x0b\x11\x09\x07",  # testnet3
+        "regtest": b"\xfa\xbf\xb5\xda"    # regtest
     }
 
     def __init__(self, dstaddr, dstport, rpc, callback, net="regtest", services=1):
@@ -1120,8 +1119,8 @@ class NodeConn(asyncore.dispatcher):
         self.dstaddr = dstaddr
         self.dstport = dstport
         self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
-        self.sendbuf = ""
-        self.recvbuf = ""
+        self.sendbuf = b""
+        self.recvbuf = b""
         self.ver_send = 209
         self.ver_recv = 209
         self.last_sent = 0
@@ -1158,8 +1157,8 @@ class NodeConn(asyncore.dispatcher):
         self.show_debug_msg("MiniNode: Closing Connection to %s:%d... "
                             % (self.dstaddr, self.dstport))
         self.state = "closed"
-        self.recvbuf = ""
-        self.sendbuf = ""
+        self.recvbuf = b""
+        self.sendbuf = b""
         try:
             self.close()
         except:
@@ -1202,7 +1201,7 @@ class NodeConn(asyncore.dispatcher):
                 if self.ver_recv < 209:
                     if len(self.recvbuf) < 4 + 12 + 4:
                         return
-                    command = self.recvbuf[4:4+12].split("\x00", 1)[0]
+                    command = self.recvbuf[4:4+12].split(b"\x00", 1)[0]
                     msglen = struct.unpack("<i", self.recvbuf[4+12:4+12+4])[0]
                     checksum = None
                     if len(self.recvbuf) < 4 + 12 + 4 + msglen:
@@ -1212,7 +1211,7 @@ class NodeConn(asyncore.dispatcher):
                 else:
                     if len(self.recvbuf) < 4 + 12 + 4 + 4:
                         return
-                    command = self.recvbuf[4:4+12].split("\x00", 1)[0]
+                    command = self.recvbuf[4:4+12].split(b"\x00", 1)[0]
                     msglen = struct.unpack("<i", self.recvbuf[4+12:4+12+4])[0]
                     checksum = self.recvbuf[4+12+4:4+12+4+4]
                     if len(self.recvbuf) < 4 + 12 + 4 + 4 + msglen:
@@ -1242,7 +1241,7 @@ class NodeConn(asyncore.dispatcher):
         data = message.serialize()
         tmsg = self.MAGIC_BYTES[self.network]
         tmsg += command
-        tmsg += "\x00" * (12 - len(command))
+        tmsg += b"\x00" * (12 - len(command))
         tmsg += struct.pack("<I", len(data))
         if self.ver_send >= 209:
             th = sha256(data)
@@ -1254,11 +1253,11 @@ class NodeConn(asyncore.dispatcher):
             self.last_sent = time.time()
 
     def got_message(self, message):
-        if message.command == "version":
+        if message.command == b"version":
             if message.nVersion <= BIP0031_VERSION:
-                self.messagemap['ping'] = msg_ping_prebip31
+                self.messagemap[b'ping'] = msg_ping_prebip31
         if self.last_sent + 30 * 60 < time.time():
-            self.send_message(self.messagemap['ping']())
+            self.send_message(self.messagemap[b'ping']())
         self.show_debug_msg("Recv %s" % repr(message))
         self.cb.deliver(self, message)
 
diff --git a/qa/rpc-tests/test_framework/netutil.py b/qa/rpc-tests/test_framework/netutil.py
index 4e4c81d397..c76de93429 100644
--- a/qa/rpc-tests/test_framework/netutil.py
+++ b/qa/rpc-tests/test_framework/netutil.py
@@ -4,13 +4,14 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 # Linux network utilities
+
 import sys
 import socket
 import fcntl
 import struct
 import array
 import os
-import binascii
+from binascii import unhexlify, hexlify
 
 # Roughly based on http://voorloopnul.com/blog/a-python-netstat-in-less-than-100-lines-of-code/ by Ricardo Pascal
 STATE_ESTABLISHED = '01'
@@ -43,7 +44,7 @@ def _remove_empty(array):
 def _convert_ip_port(array):
     host,port = array.split(':')
     # convert host from mangled-per-four-bytes form as used by kernel
-    host = binascii.unhexlify(host)
+    host = unhexlify(host)
     host_out = ''
     for x in range(0, len(host) // 4):
         (val,) = struct.unpack('=I', host[x*4:(x+1)*4])
@@ -94,7 +95,7 @@ def all_interfaces():
     max_possible = 8 # initial value
     while True:
         bytes = max_possible * struct_size
-        names = array.array('B', '\0' * bytes)
+        names = array.array('B', b'\0' * bytes)
         outbytes = struct.unpack('iL', fcntl.ioctl(
             s.fileno(),
             0x8912,  # SIOCGIFCONF
@@ -105,7 +106,7 @@ def all_interfaces():
         else:
             break
     namestr = names.tostring()
-    return [(namestr[i:i+16].split('\0', 1)[0],
+    return [(namestr[i:i+16].split(b'\0', 1)[0],
              socket.inet_ntoa(namestr[i+20:i+24]))
             for i in range(0, outbytes, struct_size)]
 
@@ -136,4 +137,4 @@ def addr_to_hex(addr):
         addr = sub[0] + ([0] * nullbytes) + sub[1]
     else:
         raise ValueError('Could not parse address %s' % addr)
-    return binascii.hexlify(bytearray(addr))
+    return hexlify(bytearray(addr)).decode('ascii')
diff --git a/qa/rpc-tests/test_framework/script.py b/qa/rpc-tests/test_framework/script.py
index bf5e25fb27..5fb5758f81 100644
--- a/qa/rpc-tests/test_framework/script.py
+++ b/qa/rpc-tests/test_framework/script.py
@@ -629,7 +629,7 @@ class CScriptNum(object):
         neg = obj.value < 0
         absvalue = -obj.value if neg else obj.value
         while (absvalue):
-            r.append(chr(absvalue & 0xff))
+            r.append(absvalue & 0xff)
             absvalue >>= 8
         if r[-1] & 0x80:
             r.append(0x80 if neg else 0)
@@ -777,7 +777,7 @@ class CScript(bytes):
         # need to change
         def _repr(o):
             if isinstance(o, bytes):
-                return "x('%s')" % hexlify(o).decode('utf8')
+                return b"x('%s')" % hexlify(o).decode('ascii')
             else:
                 return repr(o)
 
diff --git a/qa/rpc-tests/test_framework/socks5.py b/qa/rpc-tests/test_framework/socks5.py
index 12327a6c5f..f725d97701 100644
--- a/qa/rpc-tests/test_framework/socks5.py
+++ b/qa/rpc-tests/test_framework/socks5.py
@@ -102,7 +102,7 @@ class Socks5Connection(object):
                 addr = recvall(self.conn, 4)
             elif atyp == AddressType.DOMAINNAME:
                 n = recvall(self.conn, 1)[0]
-                addr = str(recvall(self.conn, n))
+                addr = recvall(self.conn, n)
             elif atyp == AddressType.IPV6:
                 addr = recvall(self.conn, 16)
             else:
diff --git a/qa/rpc-tests/test_framework/util.py b/qa/rpc-tests/test_framework/util.py
index 5b9ce890ba..eb29fea312 100644
--- a/qa/rpc-tests/test_framework/util.py
+++ b/qa/rpc-tests/test_framework/util.py
@@ -1,6 +1,8 @@
 # Copyright (c) 2014-2015 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+
 #
 # Helpful routines for regression testing
 #
@@ -9,6 +11,8 @@
 import os
 import sys
 
+from binascii import hexlify, unhexlify
+from base64 import b64encode
 from decimal import Decimal, ROUND_DOWN
 import json
 import random
@@ -70,6 +74,15 @@ def check_json_precision():
 def count_bytes(hex_string):
     return len(bytearray.fromhex(hex_string))
 
+def bytes_to_hex_str(byte_str):
+    return hexlify(byte_str).decode('ascii')
+
+def hex_str_to_bytes(hex_str):
+    return unhexlify(hex_str.encode('ascii'))
+
+def str_to_b64str(string):
+    return b64encode(string.encode('utf-8')).decode('ascii')
+
 def sync_blocks(rpc_connections, wait=1):
     """
     Wait until everybody has the same block count
@@ -425,7 +438,7 @@ def assert_is_hash_string(string, length=64):
             "String %r contains invalid characters for a hash." % string)
 
 def satoshi_round(amount):
-    return  Decimal(amount).quantize(Decimal('0.00000001'), rounding=ROUND_DOWN)
+    return Decimal(amount).quantize(Decimal('0.00000001'), rounding=ROUND_DOWN)
 
 # Helper to create at least "count" utxos
 # Pass in a fee that is sufficient for relay and mining new transactions.
diff --git a/qa/rpc-tests/zmq_test.py b/qa/rpc-tests/zmq_test.py
index 88532541ab..3a8d62ef2e 100755
--- a/qa/rpc-tests/zmq_test.py
+++ b/qa/rpc-tests/zmq_test.py
@@ -28,8 +28,8 @@ class ZMQTest (BitcoinTestFramework):
     def setup_nodes(self):
         self.zmqContext = zmq.Context()
         self.zmqSubSocket = self.zmqContext.socket(zmq.SUB)
-        self.zmqSubSocket.setsockopt(zmq.SUBSCRIBE, "hashblock")
-        self.zmqSubSocket.setsockopt(zmq.SUBSCRIBE, "hashtx")
+        self.zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"hashblock")
+        self.zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"hashtx")
         self.zmqSubSocket.connect("tcp://127.0.0.1:%i" % self.port)
         return start_nodes(4, self.options.tmpdir, extra_args=[
             ['-zmqpubhashtx=tcp://127.0.0.1:'+str(self.port), '-zmqpubhashblock=tcp://127.0.0.1:'+str(self.port)],
@@ -46,13 +46,13 @@ class ZMQTest (BitcoinTestFramework):
 
         print "listen..."
         msg = self.zmqSubSocket.recv_multipart()
-        topic = str(msg[0])
+        topic = msg[0]
         body = msg[1]
 
         msg = self.zmqSubSocket.recv_multipart()
-        topic = str(msg[0])
+        topic = msg[0]
         body = msg[1]
-        blkhash = binascii.hexlify(body)
+        blkhash = bytes_to_hex_str(body)
 
         assert_equal(genhashes[0], blkhash) #blockhash from generate must be equal to the hash received over zmq
 
@@ -63,10 +63,10 @@ class ZMQTest (BitcoinTestFramework):
         zmqHashes = []
         for x in range(0,n*2):
             msg = self.zmqSubSocket.recv_multipart()
-            topic = str(msg[0])
+            topic = msg[0]
             body = msg[1]
-            if topic == "hashblock":
-                zmqHashes.append(binascii.hexlify(body))
+            if topic == b"hashblock":
+                zmqHashes.append(bytes_to_hex_str(body))
 
         for x in range(0,n):
             assert_equal(genhashes[x], zmqHashes[x]) #blockhash from generate must be equal to the hash received over zmq
@@ -77,11 +77,11 @@ class ZMQTest (BitcoinTestFramework):
 
         # now we should receive a zmq msg because the tx was broadcast
         msg = self.zmqSubSocket.recv_multipart()
-        topic = str(msg[0])
+        topic = msg[0]
         body = msg[1]
         hashZMQ = ""
-        if topic == "hashtx":
-            hashZMQ = binascii.hexlify(body)
+        if topic == b"hashtx":
+            hashZMQ = bytes_to_hex_str(body)
 
         assert_equal(hashRPC, hashZMQ) #blockhash from generate must be equal to the hash received over zmq