diff --git a/electrum/bitcoin.py b/electrum/bitcoin.py
index 3066692c9..41e83c53d 100644
--- a/electrum/bitcoin.py
+++ b/electrum/bitcoin.py
@@ -31,7 +31,7 @@ from . import version
 from . import segwit_addr
 from . import constants
 from . import ecc
-from .crypto import Hash, sha256, hash_160, hmac_oneshot
+from .crypto import sha256d, sha256, hash_160, hmac_oneshot
 
 
 ################################## transactions
@@ -199,7 +199,7 @@ is_seed = lambda x: bool(seed_type(x))
 def hash160_to_b58_address(h160: bytes, addrtype):
     s = bytes([addrtype])
     s += h160
-    return base_encode(s+Hash(s)[0:4], base=58)
+    return base_encode(s+sha256d(s)[0:4], base=58)
 
 
 def b58_address_to_hash160(addr):
@@ -382,7 +382,7 @@ class InvalidChecksum(Exception):
 
 
 def EncodeBase58Check(vchIn):
-    hash = Hash(vchIn)
+    hash = sha256d(vchIn)
     return base_encode(vchIn + hash[0:4], base=58)
 
 
@@ -390,7 +390,7 @@ def DecodeBase58Check(psz):
     vchRet = base_decode(psz, None, base=58)
     key = vchRet[0:-4]
     csum = vchRet[-4:]
-    hash = Hash(key)
+    hash = sha256d(key)
     cs32 = hash[0:4]
     if cs32 != csum:
         raise InvalidChecksum('expected {}, actual {}'.format(bh2u(cs32), bh2u(csum)))
diff --git a/electrum/blockchain.py b/electrum/blockchain.py
index ccc04138b..0f8749056 100644
--- a/electrum/blockchain.py
+++ b/electrum/blockchain.py
@@ -25,7 +25,8 @@ import threading
 from typing import Optional, Dict
 
 from . import util
-from .bitcoin import Hash, hash_encode, int_to_hex, rev_hex
+from .bitcoin import hash_encode, int_to_hex, rev_hex
+from .crypto import sha256d
 from . import constants
 from .util import bfh, bh2u
 from .simple_config import SimpleConfig
@@ -71,7 +72,7 @@ def hash_header(header: dict) -> str:
         return '0' * 64
     if header.get('prev_block_hash') is None:
         header['prev_block_hash'] = '00'*32
-    return hash_encode(Hash(bfh(serialize_header(header))))
+    return hash_encode(sha256d(bfh(serialize_header(header))))
 
 
 blockchains = {}  # type: Dict[int, Blockchain]
diff --git a/electrum/crypto.py b/electrum/crypto.py
index de8b6b5d7..417a433bc 100644
--- a/electrum/crypto.py
+++ b/electrum/crypto.py
@@ -27,6 +27,7 @@ import base64
 import os
 import hashlib
 import hmac
+from typing import Union
 
 import pyaes
 
@@ -104,14 +105,14 @@ def DecodeAES(secret, e):
 
 def pw_encode(s, password):
     if password:
-        secret = Hash(password)
+        secret = sha256d(password)
         return EncodeAES(secret, to_bytes(s, "utf8")).decode('utf8')
     else:
         return s
 
 def pw_decode(s, password):
     if password is not None:
-        secret = Hash(password)
+        secret = sha256d(password)
         try:
             d = to_string(DecodeAES(secret, s), "utf8")
         except Exception:
@@ -121,12 +122,12 @@ def pw_decode(s, password):
         return s
 
 
-def sha256(x: bytes) -> bytes:
+def sha256(x: Union[bytes, str]) -> bytes:
     x = to_bytes(x, 'utf8')
     return bytes(hashlib.sha256(x).digest())
 
 
-def Hash(x: bytes) -> bytes:
+def sha256d(x: Union[bytes, str]) -> bytes:
     x = to_bytes(x, 'utf8')
     out = bytes(sha256(sha256(x)))
     return out
diff --git a/electrum/ecc.py b/electrum/ecc.py
index c5e77278f..4a3cd2e97 100644
--- a/electrum/ecc.py
+++ b/electrum/ecc.py
@@ -34,7 +34,7 @@ from ecdsa.ellipticcurve import Point
 from ecdsa.util import string_to_number, number_to_string
 
 from .util import bfh, bh2u, assert_bytes, print_error, to_bytes, InvalidPassword, profiler
-from .crypto import (Hash, aes_encrypt_with_iv, aes_decrypt_with_iv, hmac_oneshot)
+from .crypto import (sha256d, aes_encrypt_with_iv, aes_decrypt_with_iv, hmac_oneshot)
 from .ecc_fast import do_monkey_patching_of_python_ecdsa_internals_with_libsecp256k1
 from . import msqr
 
@@ -252,7 +252,7 @@ class ECPubkey(object):
 
     def verify_message_for_address(self, sig65: bytes, message: bytes) -> None:
         assert_bytes(message)
-        h = Hash(msg_magic(message))
+        h = sha256d(msg_magic(message))
         public_key, compressed = self.from_signature65(sig65, h)
         # check public key
         if public_key != self:
@@ -313,7 +313,7 @@ def verify_message_with_address(address: str, sig65: bytes, message: bytes):
     from .bitcoin import pubkey_to_address
     assert_bytes(sig65, message)
     try:
-        h = Hash(msg_magic(message))
+        h = sha256d(msg_magic(message))
         public_key, compressed = ECPubkey.from_signature65(sig65, h)
         # check public key using the address
         pubkey_hex = public_key.get_public_key_hex(compressed)
@@ -403,7 +403,7 @@ class ECPrivkey(ECPubkey):
                 raise Exception("error: cannot sign message. no recid fits..")
 
         message = to_bytes(message, 'utf8')
-        msg_hash = Hash(msg_magic(message))
+        msg_hash = sha256d(msg_magic(message))
         sig_string = self.sign(msg_hash,
                                sigencode=sig_string_from_r_and_s,
                                sigdecode=get_r_and_s_from_sig_string)
diff --git a/electrum/keystore.py b/electrum/keystore.py
index f991a4f5d..a942d0751 100644
--- a/electrum/keystore.py
+++ b/electrum/keystore.py
@@ -35,7 +35,7 @@ from .bip32 import (bip32_public_derivation, deserialize_xpub, CKD_pub,
                     bip32_private_key, bip32_derivation, BIP32_PRIME,
                     is_xpub, is_xprv)
 from .ecc import string_to_number, number_to_string
-from .crypto import pw_decode, pw_encode, Hash
+from .crypto import pw_decode, pw_encode, sha256d
 from .util import (PrintError, InvalidPassword, hfu, WalletFileException,
                    BitcoinException, bh2u, bfh, print_error, inv_dict)
 from .mnemonic import Mnemonic, load_wordlist
@@ -413,7 +413,7 @@ class Old_KeyStore(Deterministic_KeyStore):
 
     @classmethod
     def get_sequence(self, mpk, for_change, n):
-        return string_to_number(Hash(("%d:%d:"%(n, for_change)).encode('ascii') + bfh(mpk)))
+        return string_to_number(sha256d(("%d:%d:"%(n, for_change)).encode('ascii') + bfh(mpk)))
 
     @classmethod
     def get_pubkey_from_mpk(self, mpk, for_change, n):
diff --git a/electrum/plugins/cosigner_pool/qt.py b/electrum/plugins/cosigner_pool/qt.py
index 0f9d4fb37..175e469cc 100644
--- a/electrum/plugins/cosigner_pool/qt.py
+++ b/electrum/plugins/cosigner_pool/qt.py
@@ -133,7 +133,7 @@ class Plugin(BasePlugin):
         for key, keystore in wallet.keystores.items():
             xpub = keystore.get_master_public_key()
             K = bip32.deserialize_xpub(xpub)[-1]
-            _hash = bh2u(crypto.Hash(K))
+            _hash = bh2u(crypto.sha256d(K))
             if not keystore.is_watching_only():
                 self.keys.append((key, _hash, window))
             else:
diff --git a/electrum/plugins/digitalbitbox/digitalbitbox.py b/electrum/plugins/digitalbitbox/digitalbitbox.py
index 24f676e0e..bb9131c3d 100644
--- a/electrum/plugins/digitalbitbox/digitalbitbox.py
+++ b/electrum/plugins/digitalbitbox/digitalbitbox.py
@@ -4,7 +4,7 @@
 #
 
 try:
-    from electrum.crypto import Hash, EncodeAES, DecodeAES
+    from electrum.crypto import sha256d, EncodeAES, DecodeAES
     from electrum.bitcoin import (TYPE_ADDRESS, push_script, var_int, public_key_to_p2pkh,
                                   is_address)
     from electrum.bip32 import serialize_xpub, deserialize_xpub
@@ -395,7 +395,7 @@ class DigitalBitbox_Client():
     def hid_send_encrypt(self, msg):
         reply = ""
         try:
-            secret = Hash(self.password)
+            secret = sha256d(self.password)
             msg = EncodeAES(secret, msg)
             reply = self.hid_send_plain(msg)
             if 'ciphertext' in reply:
@@ -448,7 +448,7 @@ class DigitalBitbox_KeyStore(Hardware_KeyStore):
         try:
             message = message.encode('utf8')
             inputPath = self.get_derivation() + "/%d/%d" % sequence
-            msg_hash = Hash(msg_magic(message))
+            msg_hash = sha256d(msg_magic(message))
             inputHash = to_hexstr(msg_hash)
             hasharray = []
             hasharray.append({'hash': inputHash, 'keypath': inputPath})
@@ -526,7 +526,7 @@ class DigitalBitbox_KeyStore(Hardware_KeyStore):
                     if x_pubkey in derivations:
                         index = derivations.get(x_pubkey)
                         inputPath = "%s/%d/%d" % (self.get_derivation(), index[0], index[1])
-                        inputHash = Hash(binascii.unhexlify(tx.serialize_preimage(i)))
+                        inputHash = sha256d(binascii.unhexlify(tx.serialize_preimage(i)))
                         hasharray_i = {'hash': to_hexstr(inputHash), 'keypath': inputPath}
                         hasharray.append(hasharray_i)
                         inputhasharray.append(inputHash)
@@ -577,7 +577,7 @@ class DigitalBitbox_KeyStore(Hardware_KeyStore):
                     },
                 }
                 if tx_dbb_serialized is not None:
-                    msg["sign"]["meta"] = to_hexstr(Hash(tx_dbb_serialized))
+                    msg["sign"]["meta"] = to_hexstr(sha256d(tx_dbb_serialized))
                 msg = json.dumps(msg).encode('ascii')
                 dbb_client = self.plugin.get_client(self)
 
diff --git a/electrum/tests/test_bitcoin.py b/electrum/tests/test_bitcoin.py
index 399ffc2e2..e11cee4ec 100644
--- a/electrum/tests/test_bitcoin.py
+++ b/electrum/tests/test_bitcoin.py
@@ -11,7 +11,7 @@ from electrum.bitcoin import (public_key_to_p2pkh, address_from_private_key,
 from electrum.bip32 import (bip32_root, bip32_public_derivation, bip32_private_derivation,
                             xpub_from_xprv, xpub_type, is_xprv, is_bip32_derivation,
                             is_xpub, convert_bip32_path_to_list_of_uint32)
-from electrum.crypto import Hash
+from electrum.crypto import sha256d
 from electrum import ecc, crypto, constants
 from electrum.ecc import number_to_string, string_to_number
 from electrum.transaction import opcodes
@@ -246,13 +246,9 @@ class Test_bitcoin(SequentialTestCase):
         enc = crypto.pw_encode(payload, password)
         self.assertRaises(Exception, crypto.pw_decode, enc, wrong_password)
 
-    def test_hash(self):
-        """Make sure the Hash function does sha256 twice"""
-        payload = u"test"
-        expected = b'\x95MZI\xfdp\xd9\xb8\xbc\xdb5\xd2R&x)\x95\x7f~\xf7\xfalt\xf8\x84\x19\xbd\xc5\xe8"\t\xf4'
-
-        result = Hash(payload)
-        self.assertEqual(expected, result)
+    def test_sha256d(self):
+        self.assertEqual(b'\x95MZI\xfdp\xd9\xb8\xbc\xdb5\xd2R&x)\x95\x7f~\xf7\xfalt\xf8\x84\x19\xbd\xc5\xe8"\t\xf4',
+                         sha256d(u"test"))
 
     def test_int_to_hex(self):
         self.assertEqual('00', int_to_hex(0, 1))
diff --git a/electrum/transaction.py b/electrum/transaction.py
index 96bf6f991..b9134eaab 100644
--- a/electrum/transaction.py
+++ b/electrum/transaction.py
@@ -39,7 +39,7 @@ from .bitcoin import (TYPE_ADDRESS, TYPE_PUBKEY, TYPE_SCRIPT, hash_160,
                       hash160_to_p2sh, hash160_to_p2pkh, hash_to_segwit_addr,
                       hash_encode, var_int, TOTAL_COIN_SUPPLY_LIMIT_IN_BTC, COIN,
                       op_push, int_to_hex, push_script, b58_address_to_hash160)
-from .crypto import Hash
+from .crypto import sha256d
 from .keystore import xpubkey_to_address, xpubkey_to_pubkey
 
 
@@ -728,7 +728,7 @@ class Transaction:
             sig = signatures[i]
             if sig in txin.get('signatures'):
                 continue
-            pre_hash = Hash(bfh(self.serialize_preimage(i)))
+            pre_hash = sha256d(bfh(self.serialize_preimage(i)))
             sig_string = ecc.sig_string_from_der_sig(bfh(sig[:-2]))
             for recid in range(4):
                 try:
@@ -1036,9 +1036,9 @@ class Transaction:
         txin = inputs[i]
         # TODO: py3 hex
         if self.is_segwit_input(txin):
-            hashPrevouts = bh2u(Hash(bfh(''.join(self.serialize_outpoint(txin) for txin in inputs))))
-            hashSequence = bh2u(Hash(bfh(''.join(int_to_hex(txin.get('sequence', 0xffffffff - 1), 4) for txin in inputs))))
-            hashOutputs = bh2u(Hash(bfh(''.join(self.serialize_output(o) for o in outputs))))
+            hashPrevouts = bh2u(sha256d(bfh(''.join(self.serialize_outpoint(txin) for txin in inputs))))
+            hashSequence = bh2u(sha256d(bfh(''.join(int_to_hex(txin.get('sequence', 0xffffffff - 1), 4) for txin in inputs))))
+            hashOutputs = bh2u(sha256d(bfh(''.join(self.serialize_output(o) for o in outputs))))
             outpoint = self.serialize_outpoint(txin)
             preimage_script = self.get_preimage_script(txin)
             scriptCode = var_int(len(preimage_script) // 2) + preimage_script
@@ -1091,14 +1091,14 @@ class Transaction:
         if not all_segwit and not self.is_complete():
             return None
         ser = self.serialize_to_network(witness=False)
-        return bh2u(Hash(bfh(ser))[::-1])
+        return bh2u(sha256d(bfh(ser))[::-1])
 
     def wtxid(self):
         self.deserialize()
         if not self.is_complete():
             return None
         ser = self.serialize_to_network(witness=True)
-        return bh2u(Hash(bfh(ser))[::-1])
+        return bh2u(sha256d(bfh(ser))[::-1])
 
     def add_inputs(self, inputs):
         self._inputs.extend(inputs)
@@ -1219,7 +1219,7 @@ class Transaction:
         self.raw = self.serialize()
 
     def sign_txin(self, txin_index, privkey_bytes) -> str:
-        pre_hash = Hash(bfh(self.serialize_preimage(txin_index)))
+        pre_hash = sha256d(bfh(self.serialize_preimage(txin_index)))
         privkey = ecc.ECPrivkey(privkey_bytes)
         sig = privkey.sign_transaction(pre_hash)
         sig = bh2u(sig) + '01'
diff --git a/electrum/verifier.py b/electrum/verifier.py
index 32ea4aa41..27913ce13 100644
--- a/electrum/verifier.py
+++ b/electrum/verifier.py
@@ -27,7 +27,7 @@ from typing import Sequence, Optional, TYPE_CHECKING
 import aiorpcx
 
 from .util import bh2u, VerifiedTxInfo, NetworkJobOnDefaultServer
-from .crypto import Hash
+from .crypto import sha256d
 from .bitcoin import hash_decode, hash_encode
 from .transaction import Transaction
 from .blockchain import hash_header
@@ -140,7 +140,7 @@ class SPV(NetworkJobOnDefaultServer):
             raise MerkleVerificationFailure(e)
 
         for i, item in enumerate(merkle_branch_bytes):
-            h = Hash(item + h) if ((leaf_pos_in_tree >> i) & 1) else Hash(h + item)
+            h = sha256d(item + h) if ((leaf_pos_in_tree >> i) & 1) else sha256d(h + item)
             cls._raise_if_valid_tx(bh2u(h))
         return hash_encode(h)
 
diff --git a/electrum/wallet.py b/electrum/wallet.py
index 6379ef43c..94486eb21 100644
--- a/electrum/wallet.py
+++ b/electrum/wallet.py
@@ -48,7 +48,7 @@ from .util import (NotEnoughFunds, PrintError, UserCancelled, profiler,
 from .bitcoin import (COIN, TYPE_ADDRESS, is_address, address_to_script,
                       is_minikey)
 from .version import *
-from .crypto import Hash
+from .crypto import sha256d
 from .keystore import load_keystore, Hardware_KeyStore
 from .storage import multisig_type, STO_EV_PLAINTEXT, STO_EV_USER_PW, STO_EV_XPUB_PW, WalletStorage
 from . import transaction, bitcoin, coinchooser, paymentrequest, ecc, bip32
@@ -931,7 +931,7 @@ class Abstract_Wallet(AddressSynchronizer):
 
     def make_payment_request(self, addr, amount, message, expiration):
         timestamp = int(time.time())
-        _id = bh2u(Hash(addr + "%d"%timestamp))[0:10]
+        _id = bh2u(sha256d(addr + "%d"%timestamp))[0:10]
         r = {'time':timestamp, 'amount':amount, 'exp':expiration, 'address':addr, 'memo':message, 'id':_id}
         return r