在文本文件中使用私钥编写带符号散列的字节数组并以相同格式取回它时出现问题

import base64
import hashlib
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import padding
from cryptography.hazmat.backends import default_backend

# 读取私钥
with open("private_key.pem", "rb") as key_file:
    private_key = serialization.load_pem_private_key(
        key_file.read(),
        password=None,
        backend=default_backend()
    )

# 要签名的数据
data = b"example data"

# 计算散列值
hasher = hashlib.sha256()
hasher.update(data)
digest = hasher.digest()

# 签名
signature = private_key.sign(
    digest,
    padding.PSS(
        mgf=padding.MGF1(hashes.SHA256()),
        salt_length=padding.PSS.MAX_LENGTH
    ),
    hashes.SHA256()
)

# 将签名和散列值编码为Base64并写入文件
with open("signed_hash.txt", "w") as file:
    file.write(base64.b64encode(digest).decode('utf-8'))
    file.write("\n")
    file.write(base64.b64encode(signature).decode('utf-8'))

import base64
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import padding
from cryptography.exceptions import InvalidSignature

# 读取私钥
with open("private_key.pem", "rb") as key_file:
    private_key = serialization.load_pem_private_key(
        key_file.read(),
        password=None,
        backend=default_backend()
    )

# 从文件中读取签名和散列值
with open("signed_hash.txt", "r") as file:
    digest_base64 = file.readline().strip()
    signature_base64 = file.readline().strip()

# 解码Base64
digest = base64.b64decode(digest_base64)
signature = base64.b64decode(signature_base64)

# 验证签名
try:
    public_key = private_key.public_key()
    public_key.verify(
        signature,
        digest,
        padding.PSS(
            mgf=padding.MGF1(hashes.SHA256()),
            salt_length=padding.PSS.MAX_LENGTH
        ),
        hashes.SHA256()
    )
    print("签名验证成功")
except InvalidSignature:
    print("签名验证失败")