如何验证 python 中的签名文件

Question

背景

我已经使用 openssl SHA256 和私钥签署了一个文件，如下所示：

with subprocess.Popen(
        # Pipe the signature to openssl to convert it from raw binary encoding to base64 encoding.
        # This will prevent any potential corruption due to line ending conversions, and also allows 
        # a human to read and copy the signature (e.g. for manual verification).
        'openssl dgst -sha256 -sign private.key sign_me.zip | openssl base64 > signature.sha256',
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
        shell=True,
) as proc:
    out, _ = proc.communicate()

要求

我需要用signature.sha256和public_key.crt来验证sign_me.zip没有被修改
兼容 Python 3.2 - 3.4
需要在 Windows 和 Redhat 上工作，并且不能保证 OpenSSL 会在路径上或在已知位置。理想情况下，我想使用核心 Python 模块，但如果它能降低复杂性，我会考虑第 3 方模块。

我试过的

我进行了大量搜索，试图弄清楚如何做到这一点，但一直未能找到满意的答案。这是我尝试过 and/or 研究的事情列表：

我可以通过以下 shell 命令手动验证签名。由于要求 3，这不能作为永久解决方案。

openssl dgst -sha256 -verify <(openssl x509 -in public_key.crt -pubkey -noout) -signature signature.sha256 sign_me.zip
我找到了 this question, which is almost exactly what I want to do. It hasn't been answered or even commented on in nearly 2 years. It mentions the ssl python library，它主要处理 client/server 证书和套接字。
appears to use the crypto library to verify a "SHA256withRSA and PKCS1 padding" signature. Unfortunately it targets Python 2.7, and additionally I wasn't able to locate the verify() method documentation in the Python 2.7 crypto 问题引用的模块。
我还发现了一个名为 cryptography 的第三方模块。 Stack Overflow 上的共识似乎是，这是用于加密等的 latest/greatest 模块，但我找不到符合我要求的文档。

也许我遗漏了一些明显的东西？我没有用 security/encryption/hashing 做过很多工作，因此欢迎提供反馈。

Answer 1

感谢 Patrick Mevzek 为我指明了正确的方向。我最终使用 Cryptography 模块找到了以下解决我的问题的方法。我最终改变了我签署文件的方式以匹配我稍后验证它的方式。

密钥生成：

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa

# Generate the public/private key pair.
private_key = rsa.generate_private_key(
    public_exponent = 65537,
    key_size = 4096,
    backend = default_backend(),
)

# Save the private key to a file.
with open('private.key', 'wb') as f:
    f.write(
        private_key.private_bytes(
            encoding=serialization.Encoding.PEM,
            format=serialization.PrivateFormat.TraditionalOpenSSL,
            encryption_algorithm=serialization.NoEncryption(),
        )
    )

# Save the public key to a file.
with open('public.pem', 'wb') as f:
    f.write(
        private_key.public_key().public_bytes(
            encoding = serialization.Encoding.PEM,
            format = serialization.PublicFormat.SubjectPublicKeyInfo,
        )
    )

签名：

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

# Load the private key. 
with open('private.key', 'rb') as key_file: 
    private_key = serialization.load_pem_private_key(
        key_file.read(),
        password = None,
        backend = default_backend(),
    )

# Load the contents of the file to be signed.
with open('payload.dat', 'rb') as f:
    payload = f.read()

# Sign the payload file.
signature = base64.b64encode(
    private_key.sign(
        payload,
        padding.PSS(
            mgf = padding.MGF1(hashes.SHA256()),
            salt_length = padding.PSS.MAX_LENGTH,
        ),
        hashes.SHA256(),
    )
)
with open('signature.sig', 'wb') as f:
    f.write(signature)

验证：

import base64
import cryptography.exceptions
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import padding
from cryptography.hazmat.primitives.serialization import load_pem_public_key

# Load the public key.
with open('public.pem', 'rb') as f:
    public_key = load_pem_public_key(f.read(), default_backend())

# Load the payload contents and the signature.
with open('payload.dat', 'rb') as f:
    payload_contents = f.read()
with open('signature.sig', 'rb') as f:
    signature = base64.b64decode(f.read())

# Perform the verification.
try:
    public_key.verify(
        signature,
        payload_contents,
        padding.PSS(
            mgf = padding.MGF1(hashes.SHA256()),
            salt_length = padding.PSS.MAX_LENGTH,
        ),
        hashes.SHA256(),
    )
except cryptography.exceptions.InvalidSignature as e:
    print('ERROR: Payload and/or signature files failed verification!')

如何验证 python 中的签名文件

How to verify a signed file in python

ssl

openssl

cryptography

sha256

python-3.x

背景

要求

我试过的