Pycrypto不一致地无法验证从文件加载的签名

Question

我试图有一个程序签名，然后稍后验证文件的内容。然而，虽然第一次验证总是返回true，但一旦数据被写入文件然后再次加载，验证通常会失败，但有时会成功。

即使代码失败，两个print signature和print hash.hexdigest()调用的输出在视觉上是相同的。

我的测试代码是:

from Crypto.Hash import SHA256
from Crypto.PublicKey import RSA
from Crypto.Signature import PKCS1_PSS
def generate():
    key_file = open("TestPrivateKey")
    private_key = RSA.importKey(key_file)
    public_key = private_key.publickey()
    seed_file = open("Seed")
    plaintext = seed_file.read()
    hash = SHA256.new(plaintext)
    signer = PKCS1_PSS.new(private_key)
    signature =  signer.sign(hash)
    plaintext_file = open("plaintext", 'w')
    plaintext_file.write(plaintext)
    signature_file = open("signature", 'w')
    signature_file.write(signature)
    print signature
    print hash.hexdigest()
    verifier = PKCS1_PSS.new(public_key)
    print verifier.verify(hash, signature)
def verification_test():
    plaintext_file = open("plaintext")
    signature_file = open("signature", 'rb')
    plaintext = plaintext_file.read()
    public_key = RSA.importKey(open("TestPublicKey"))
    signature = signature_file.read()
    print signature
    hash = SHA256.new(plaintext)
    print hash.hexdigest()
    verifier = PKCS1_PSS.new(public_key)
    return verifier.verify(hash, signature)

if __name__ == '__main__':
    generate()
    print verification_test()

有谁知道我犯了什么错误吗?当签名被写入文件，然后再读回来时，一定发生了什么，但我不知道是什么。 编辑:在我运行这个脚本之前，我运行初始化函数:

from Crypto.PublicKey import RSA
def create_keys():
    private_key = RSA.generate(4096)
    file = open("TestPrivateKey", 'w')
    file.write(private_key.exportKey())
    file = open("TestPublicKey", 'w')
    file.write(private_key.publickey().exportKey())
def create_seed():
    file = open("Seed", 'w')
    file.write("Test")

Answer 1

我注意到你的代码有两个问题。

首先，将任意二进制数据写入为文本打开的文件:

signature_file = open("signature", 'w')  #bad
signature_file.write(signature)

应:

signature_file = open("signature", 'wb')  #good
signature_file.write(signature)

第二，你从不关闭你的文件。试试这个:

with open("signature", 'wb') as signature_file:
    signature_file.write(signature)

，对于所有其他打开的文件也是如此。

---

from Crypto.Hash import SHA256
from Crypto.PublicKey import RSA
from Crypto.Signature import PKCS1_PSS
def generate():
    with open("TestPrivateKey") as key_file:
        private_key = RSA.importKey(key_file)
    public_key = private_key.publickey()
    with open("Seed") as seed_file:
        plaintext = seed_file.read()
    hash = SHA256.new(plaintext)
    signer = PKCS1_PSS.new(private_key)
    signature =  signer.sign(hash)
    with open("plaintext", 'w') as plaintext_file:
        plaintext_file.write(plaintext)
    with open("signature", 'wb') as signature_file:
        signature_file.write(signature)
    #print signature
    print hash.hexdigest()
    verifier = PKCS1_PSS.new(public_key)
    print verifier.verify(hash, signature)
def verification_test():
    with open("plaintext") as plaintext_file:
        plaintext = plaintext_file.read()
    with open("signature", 'rb') as signature_file:
        signature = signature_file.read()
    with open("TestPublicKey") as public_key_file:
        public_key = RSA.importKey(public_key_file)
    #print signature
    hash = SHA256.new(plaintext)
    print hash.hexdigest()
    verifier = PKCS1_PSS.new(public_key)
    return verifier.verify(hash, signature)

if __name__ == '__main__':
    generate()
    print verification_test()