Java转Python：x509 / dsa / sha1withdsa加密怎么做？

Question

我有一段Java代码，想把它转换成Python，但我不太确定该怎么做：

import java.security.spec.X509EncodedKeySpec;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.Signature;

byte[] key = KeyReader.read(filestream) 
  //KeyReader.read(inputstream) just reads in the bytes 1 at a time from the filestream
X509EncodedKeySpec pubKey = new X509EncodedKeySpec(key);
KeyFactory keyFactory = KeyFactory.getInstance("DSA");

PublicKey pub = keyFactory.generatePublic(pubKey);

Signature signature = Signature.getInstance("SHA1withDSA");
signature.initVerify(pub)
signature.update(a_byte_string) //doesn't matter

我对怎么在Python中实现这个有点迷茫，特别是SHA1withDSA这一部分。我对Python的加密库（具体来说是m2crypto）了解得不够多，所以不知道怎么对应这些函数（而且我也找不到什么好的教程来帮助我）。

Answer 1

我不太明白这段Java代码，不过你是不是想要做这个呢？

from M2Crypto import X509

x509 = X509.load_cert(filename)
assert x509.verify() == 1