[英]AttributeError: '_hashlib.HASH' object has no attribute 'startswith'
class Block:
def __init__(self):
self.verified_transactions = []
self.previous_block_hash = ""
self.Nonce = ""
def mine(message, difficulty=1):
assert difficulty >= 1
prefix = '1' * difficulty
for i in range(1000):
digest = hashlib.sha256(str(hash(message)).encode('utf-8') + str(i).encode('utf-8'))
if digest.startswith(prefix):
print ("after " + str(i) + " iterations found nonce: "+ digest)
return digest
error: Traceback (most recent call last):
File "c:/Users/thoma/Desktop/Client.py", line 113, in <module>
Block.mine ("test message", 2)
File "c:/Users/thoma/Desktop/Client.py", line 94, in mine
if str(digest.startswith(prefix)):
AttributeError: '_hashlib.HASH' object has no attribute 'startswith'
---- complete code----- ---- 完整代码-----
# import libraries
import hashlib
import random
import string
import json
import binascii
import numpy as np
import pandas as pd
import pylab as pl
import logging
import datetime
import collections
# following imports are required by PKI
import Cryptodome
import Cryptodome.Random
from Cryptodome.Hash import SHA
from Cryptodome.PublicKey import RSA
from Cryptodome.Signature import PKCS1_v1_5
transactions = []
last_block_hash = ""
TPCoins = []
def sha256(message):
return hashlib.sha256(message.encode('ascii')).hexdigest()
class Client:
def __init__(self):
random = Cryptodome.Random.new().read
self._private_key = RSA.generate(1024, random)
self._public_key = self._private_key.publickey()
self._signer = PKCS1_v1_5.new(self._private_key)
@property
def identity(self):
return binascii.hexlify(self._public_key.exportKey(format='DER')).decode('ascii')
class Transaction:
def __init__(self, sender, recipient, value):
self.sender = sender
self.recipient = recipient
self.value = value
self.time = datetime.datetime.now()
def to_dict(self):
if self.sender == "Genesis":
identity = "Genesis"
else:
identity = self.sender.identity
return collections.OrderedDict({
'sender': identity,
'recipient': self.recipient,
'value': self.value,
'time' : self.time})
def sign_transaction(self):
private_key = self.sender._private_key
signer = PKCS1_v1_5.new(private_key)
h = SHA.new(str(self.to_dict()).encode('utf8'))
return binascii.hexlify(signer.sign(h)).decode('ascii')
def display_transaction(transaction):
#for transaction in transactions:
dict = transaction.to_dict()
print ("sender: " + dict['sender'])
print ('-----')
print ("recipient: " + dict['recipient'])
print ('-----')
print ("value: " + str(dict['value']))
print ('-----')
print ("time: " + str(dict['time']))
print ('-----')
def dump_blockchain (self):
print ("Number of blocks in the chain: " + str(len (self)))
for x in range (len(TPCoins)):
block_temp = TPCoins[x]
print ("block # " + str(x))
for transaction in block_temp.verified_transactions:
Transaction.display_transaction (transaction)
print ('--------------')
print ('=====================================')
class Block:
def __init__(self):
self.verified_transactions = []
self.previous_block_hash = ""
self.Nonce = ""
def mine(message, difficulty=1):
assert difficulty >= 1
prefix = '1' * difficulty
for i in range(1000):
digest = hashlib.sha256(str(hash(message)).encode('utf-8') + str(i).encode('utf-8'))
if digest.startswith(prefix):
print ("after " + str(i) + " iterations found nonce: "+ digest)
return digest
#genesis block & users initialisation
Thomas = Client()
IoT_Sensor = Client()
Node = Client()
IoT_Device = Client()
t0 = Transaction("Genesis",Thomas.identity,200.0)
block0 = Block()
block0.previous_block_hash = None
Nonce = None
block0.verified_transactions.append (t0)
digest = hash (block0)
last_block_hash = digest
TPCoins.append (block0)
Transaction.dump_blockchain(TPCoins)
Block.mine ("test message", 2)
Any thoughts?有什么想法吗? I am working off a tutorial @ python blockchain tutorial我正在写一个教程@ python 区块链教程
I believe the issue is the variable digest is not a str but rather a hashlib.sha256 object and thus.startswith() is not recognised.我认为问题在于变量摘要不是 str 而是 hashlib.sha256 object 并且因此.startswith() 未被识别。 I have tried casting to str() without any luck.我尝试过强制转换为 str() ,但没有任何运气。
Thanks for any help everyone.感谢大家的帮助。
Solution thanks to furas:)感谢 furas 的解决方案:)
def mine(message, difficulty=1):
assert difficulty >= 1
prefix = '1' * difficulty
for i in range(1000):
digest = sha256(str(hash(message)) + str(i))
if digest.startswith(prefix):
print ("after " + str(i) + " iterations found nonce: "+ digest)
return digest
output: output:
after 303 iterations found nonce: 11337d455c3d425b33cbeeb23fc87d6a3e7c05bf0d27f648e6c9df2f87eea2fb
See tutorial again.再看教程。
It uses own function sha256()
instead of standard hashlib.sha256()
and this sha256()
has .hexdigest()
at the end:它使用自己的 function sha256()
而不是标准的hashlib.sha256()
并且这个sha256()
最后有.hexdigest()
:
def sha256(message):
return hashlib.sha256(message.encode('ascii')).hexdigest()
And later it uses this sha256()
before digest.startswith()
后来它在digest.startswith()
sha256()
)
digest = sha256(...)
if digest.startswith(prefix):
# ... code ...
And your forgot .hexdigest()
in your code.并且您在代码中忘记了.hexdigest()
。
digest = hashlib.sha256(...).hexdigest()
if digest.startswith(prefix):
# ... code ...
By the way: I think return digest
in tutorial is in wrong place - it will return digest
in first loop but it should do this inside if digest.startswith(prefix):
顺便说一句:我认为教程中的return digest
在错误的位置 - 它会在第一个循环中返回digest
,但if digest.startswith(prefix):
digest = hashlib.sha256(str(hash(message)).encode('utf-8') + str(i).encode('utf-8')).hexdigest()
if digest.startswith(prefix):
print("after", i, "iterations found nonce:", digest)
return digest
If after 1000 iterations it will not find digest with prefix then it will return None
如果在 1000 次迭代后找不到带有前缀的摘要,那么它将返回None
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