使用pyopenssl创建自签名证书

Question

我正在尝试使用pyopenssl生成自签名的X509v3 CA证书，并想要添加扩展的主体密钥标识符（SKID）到含有密钥标识符（AKID）的授权密钥标识符。

但是我以下的代码块没有将SKID复制到AKID，而是抛出了异常。

代码如下

import OpenSSL

key = OpenSSL.crypto.PKey()
key.generate_key(OpenSSL.crypto.TYPE_RSA, 2048)

ca = OpenSSL.crypto.X509()
ca.set_version(2)
ca.set_serial_number(1)
ca.get_subject().CN = "ca.example.com"
ca.gmtime_adj_notBefore(0)
ca.gmtime_adj_notAfter(24 * 60 * 60)
ca.set_issuer(ca.get_subject())
ca.set_pubkey(key)
ca.add_extensions([
  OpenSSL.crypto.X509Extension("basicConstraints", True,
                               "CA:TRUE, pathlen:0"),
  OpenSSL.crypto.X509Extension("keyUsage", True,
                               "keyCertSign, cRLSign"),
  OpenSSL.crypto.X509Extension("subjectKeyIdentifier", False, "hash",
                               subject=ca),
  OpenSSL.crypto.X509Extension("authorityKeyIdentifier", False, "keyid:always",issuer=ca)
  ])
ca.sign(key, "sha1")
open("MyCertificate.crt.bin", "wb").write(
            OpenSSL.crypto.dump_certificate(OpenSSL.crypto.FILETYPE_ASN1, ca))

抛出的异常如下

Traceback (most recent call last):
  File "C:\Documents and Settings\Administrator\Desktop\Certificate\certi.py", line 21, in <module>
    OpenSSL.crypto.X509Extension("authorityKeyIdentifier", False, "keyid:always",issuer=ca)
Error: [('X509 V3 routines', 'V2I_AUTHORITY_KEYID', 'unable to get issuer keyid'), ('X509 V3 routines', 'X509V3_EXT_nconf', 'error in extension')]

现在，如果我从下面的代码行中的keyid参数中删除“always”，

OpenSSL.crypto.X509Extension("authorityKeyIdentifier", False, "keyid",issuer=ca)

那么我得到的AKID keyid字段将是空的，并且它不包含如下所示的SKID。

          00:84:13:70:73:fe:29:61:5f:33:7d:b3:74:97:3b:
            3a:f3:11:01:7c:b8:37:a8:8c:72:81:ee:92:fd:91:
            8a:11:b3:b3:02:b4:97:d5:f8:1b:91:54:7e:15:49:
            26:6d
        Exponent: 65537 (0x10001)
X509v3 extensions:
    X509v3 Basic Constraints: critical
        CA:TRUE, pathlen:0
    X509v3 Key Usage: critical
        Certificate Sign, CRL Sign
    X509v3 Subject Key Identifier: 
        CE:D1:31:DE:CF:E3:E2:BC:6C:73:3D:55:F0:88:53:0A:F1:DC:31:14
    X509v3 Authority Key Identifier: 
        0.
Signature Algorithm: sha1WithRSAEncryption
     0b:7b:28:f6:b9:1e:6e:ec:53:6a:c5:77:db:c5:3f:5e:1d:ab:
     e5:43:73:eb:52:24:af:39:2b:aa:a3:f6:34:e1:92:4b:3b:5e:
     b6:1

- Britto

Answer 1

这意味着您使用的CA密钥没有设置subjectKeyIdentifier。

在您的示例中，您正在使用对尚未设置subjectKeyIdentifier 的ca的引用来创建authorityKeyIdentifier。

如果您将代码更改为：

ca.add_extensions([
  OpenSSL.crypto.X509Extension("basicConstraints", True,
                               "CA:TRUE, pathlen:0"),
  OpenSSL.crypto.X509Extension("keyUsage", True,
                               "keyCertSign, cRLSign"),
  OpenSSL.crypto.X509Extension("subjectKeyIdentifier", False, "hash",
                               subject=ca),
  ])
ca.add_extensions([
  OpenSSL.crypto.X509Extension("authorityKeyIdentifier", False, "keyid:always",issuer=ca)
  ])

那么它就有效了。

- V13