python blockchain note-3 SHA-256 hash

ハッシュ計算

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@staticmethod
    def hash(block):
        """
        Creates a SHA-256 hash of a Block
        :param block: Block
        """

        # We must make sure that the Dictionary is Ordered, or we'll have inconsistent hashes
        block_string = json.dumps(block, sort_keys=True).encode()
        return hashlib.sha256(block_string).hexdigest()
    def proof_of_work(self, last_block):
        """
        Simple Proof of Work Algorithm:
         - Find a number p' such that hash(pp') contains leading 4 zeroes
         - Where p is the previous proof, and p' is the new proof
         
        :param last_block: <dict> last Block
        :return: <int>
        """

        last_proof = last_block['proof']
        last_hash = self.hash(last_block)

        proof = 0
        while self.valid_proof(last_proof, proof, last_hash) is False:
            proof += 1

        return proof

    @staticmethod
    def valid_proof(last_proof, proof, last_hash):
        """
        Validates the Proof
        :param last_proof: <int> Previous Proof
        :param proof: <int> Current Proof
        :param last_hash: <str> The hash of the Previous Block
        :return: <bool> True if correct, False if not.
        """

        guess = f'{last_proof}{proof}{last_hash}'.encode()
        guess_hash = hashlib.sha256(guess).hexdigest()
        return guess_hash[:4] == "0000"
obj を JSON 形式の str オブジェクトに直列化する。

json.dumps(obj, *, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, default=None, sort_keys=False, **kw)


hashlib：セキュアハッシュモジュール

常に使用できるハッシュアルゴリズムのコンストラクタは sha1()、 sha224()、 sha256()、 sha384()、 sha512()、 blake2b()、 blake2s()

hash.hexdigest()：16進形式文字列を返します。
ハッシュ値 = hashlib.sha256(文字列).hexdigest()