android - pyOpenSSL 的 PKCS7 对象提供的信息非常少，如何在签名中获取公钥的 sha1 摘要

Question

我想用 Python 解析 android apk 的 CERT.RSA。我知道它可以用 pyOpenSSL 解析

import OpenSSL

cert = OpenSSL.crypto.load_certificate(OpenSSL.crypto.FILETYPE_ASN1, open('CERT.RSA', 'rb').read())

cert = OpenSSL.crypto.load_pkcs7_data(type, buffer)

证书的类型为“OpenSSL.crypto.PKCS7”。

但是现在 PKCS7 对象不完整，我无法获得我需要的属性，是否有其他方法来解析该文件？

Answer 1

Comments: I don't know if there's a way to convert it to another format so it can be parsed

您可以使用 openssl 将 PKCS#7 转换为 PEM，使用 PyOpenSSL 可以读取 PEM

openssl pkcs7 -print_certs -in sample.p7b -out sample.cer

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Question: ... how can I get the sha1 digest of the public key in the signature

它没有实现，Pull Request 自 2015 年以来就停滞了。
使用 Pull Request 中的代码，您可以做到这一点。

From: GitHub pyca/pyopenssl: implement getters for pkcs#7 certificates, crl's, and data #367

    def get_certificates(self):
        from OpenSSL.crypto import _lib, _ffi, X509
        """
        https://github.com/pyca/pyopenssl/pull/367/files#r67300900

        Returns all certificates for the PKCS7 structure, if present. Only
        objects of type ``signedData`` or ``signedAndEnvelopedData`` can embed
        certificates.

        :return: The certificates in the PKCS7, or :const:`None` if
            there are none.
        :rtype: :class:`tuple` of :class:`X509` or :const:`None`
        """
        certs = _ffi.NULL
        if self.type_is_signed():
            certs = self._pkcs7.d.sign.cert
        elif self.type_is_signedAndEnveloped():
            certs = self._pkcs7.d.signed_and_enveloped.cert

        pycerts = []
        for i in range(_lib.sk_X509_num(certs)):
            pycert = X509.__new__(X509)
            # pycert._x509 = _lib.sk_X509_value(certs, i)
            # According to comment from @ Jari Turkia
            # to prevent segfaults use '_lib.X509_dup('
            pycert._x509 = _lib.X509_dup(_lib.sk_X509_value(certs, i))
            pycerts.append(pycert)

        if not pycerts:
            return None
        return tuple(pycerts)

用法:

pkcs7 = crypto.load_pkcs7_data(crypto.FILETYPE_ASN1, open('signature.der', 'rb').read())
certs = get_certificates(pkcs7)
print(certs)
for cert in certs:
    print('digest:{}'.format(cert.digest('sha256')))

Output:

(<OpenSSL.crypto.X509 object at 0xf671b62c>, <OpenSSL.crypto.X509 object at 0xf671b86c>)
digest:b'48:19:A4:2A:56:94:22:14:73:EC:2B:01:45:9E:0B:87:92:44:26:5E:57:AF:59:F5:4C:89:F3:79:83:14:11:A3'
digest:b'25:BC:AC:86:8F:51:8B:EE:47:CC:8B:A7:78:91:7E:86:09:56:19:4B:B9:C4:10:1B:DF:13:CA:A6:54:E1:F7:4C'

使用 Python:3.4.2 - OpenSSL:17.1.0 - cryptography:1.9 - cffi:1.10.0 测试

---

使用

OpenSSL.crypto.load_pkcs7_data(type, buffer)

Load pkcs7 data from the string buffer encoded with the type type.
The type type must either FILETYPE_PEM or FILETYPE_ASN1).