Python TypeError：Unicode对象必须在散列之前进行编码答案

【问题标题】：Python TypeError: Unicode-objects must be encoded before hashingPython TypeError：Unicode对象必须在散列之前进行编码
【发布时间】：2018-11-10 06:45:51
【问题描述】：

我已经查看了此处的其他 4 个问题，但仍然无法弄清楚将 .encode() 或 .encode('utf-8') 放在哪里。我已将其注释掉以显示我尝试过的各个地方。

import hashlib as hasher

    class Block:
        def __init__(self, index, timestamp, data, previous_hash):
            self.index = index
            self.timestamp = timestamp
            self.data = data 
            self.previous_hash = previous_hash #these four items used to calculate crypHash of each block
            self.hash = self.hash_block() #helps ensure integrity throughout blockchain

        def hash_block(self):
            sha = hasher.sha256() #.encode('utf-8')
            sha.update(str(self.index)+
                str(self.timestamp)+
                str(self.data)+
                str(self.previous_hash)) #.encode() inside brackets
            return sha.hexdigest()

这是 Traceback（自下而上阅读）：

Traceback (most recent call last):
  File "blockchain.py", line 7, in <module>
    blockchain = [create_genesis_block()]
  File "/media/nobu/win10Files/Blockchain/SnakeCoin/genesis.py", line 8, in create_genesis_block
    return Block(0, date.datetime.now(), "Genesis Block", "0")
  File "/media/nobu/win10Files/Blockchain/SnakeCoin/block.py", line 9, in __init__
    self.hash = self.hash_block() #helps ensure integrity throughout blockchain
  File "/media/nobu/win10Files/Blockchain/SnakeCoin/block.py", line 16, in hash_block
    str(self.previous_hash))
TypeError: Unicode-objects must be encoded before hashing

这似乎表明str(self.previous_hash)) #.encode() inside brackets 应该是str(self.previous_hash).encode()) 但这给了我另一个错误：

Traceback (most recent call last):
  File "blockchain.py", line 7, in <module>
    blockchain = [create_genesis_block()]
  File "/media/nobu/win10Files/Blockchain/SnakeCoin/genesis.py", line 8, in create_genesis_block
    return Block(0, date.datetime.now(), "Genesis Block", "0")
  File "/media/nobu/win10Files/Blockchain/SnakeCoin/block.py", line 9, in __init__
    self.hash = self.hash_block() #helps ensure integrity throughout blockchain
  File "/media/nobu/win10Files/Blockchain/SnakeCoin/block.py", line 16, in hash_block
    str(self.previous_hash).encode())
TypeError: must be str, not bytes

所以我尝试了 encode() 和 decode() 与括号的各种组合，但这只会让我在错误之间交替。
因此，我很迷茫，希望得到一些指导。顺便说一句，这段代码来自这里的一篇 Medium 文章：Medium Snake Coin

【问题讨论】：

在编码前连接整个字符串：sha.update((str(self.index) + str(self.timestamp) + str(self.data) + str(self.previous_hash)).encode())。 update() 接受一个字符串。这可能会有所帮助：docs.python.org/2/library/hashlib.html

标签： python hash encoding typeerror

【解决方案1】：

只有bytes 字符串可以被散列。 str 是一个 Unicode 字符串。编码为字节，解码为 Unicode。

在您的.update() 中，所有四个项目都被转换为str。所以一旦你把它们连接在一起，.encode() 整个事情到bytes：

import hashlib as hasher

class Block:
    def __init__(self, index, timestamp, data, previous_hash):
        self.index = index
        self.timestamp = timestamp
        self.data = data 
        self.previous_hash = previous_hash #these four items used to calculate crypHash of each block
        self.hash = self.hash_block() #helps ensure integrity throughout blockchain

    def hash_block(self):
        sha = hasher.sha256()
        to_hash = str(self.index) + str(self.timestamp) + str(self.data) + str(self.previous_hash)
        sha.update(to_hash.encode())
        return sha.hexdigest()

【讨论】：