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mamadou
Asked: 2019-05-07 05:26:26 +0800 CST

唯一标识一个SSL证书

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我想知道如何确定给定文件是 SSL 证书。文件扩展名是否足以确定文件是否为证书？

tls certificate

1 个回答

  1. Best Answer

    SSL 证书只不过是X.509 版本 3 证书，带有一些针对常见用途的附加限制。

    主要限制当然是 X500 Common Name (CN)，它需要设置为服务器的名称。顺便说一下，Subject Alternative Name 字段可能包含更多名称。

    此外，对于大多数证书，Extended Key Usage 需要设置为 Server Authentication（对应于 OID：1.3.6.1.5.5.7.3.1）。服务器还可以设置客户端身份验证（OID：1.3.6.1.5.5.7.3.2）。

    请注意，至少对于 TLS 1.2，这些限制并未在规范中明确提及（呃），但您最好确保它们存在，除非您的浏览器/客户端开始尖叫谋杀。

    要验证文件是否为 (TLS) 证书，最简单的方法可能是使用 Windows 打开它并检查一些额外的限制。但是我个人更喜欢使用例如 OpenSSL 命令行，这样您就可以简单地输出到文本：

    openssl x509 -text -noout -in stackexchangecom.pem

    例如会输出以下内容：

    Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number:
            07:65:c6:4e:74:e5:91:d6:80:39:ca:2a:84:75:63:f0
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: C=US, O=DigiCert Inc, OU=www.digicert.com, CN=DigiCert SHA2 High Assurance Server CA
        Validity
            Not Before: Oct  5 00:00:00 2018 GMT
            Not After : Aug 14 12:00:00 2019 GMT
        Subject: C=US, ST=NY, L=New York, O=Stack Exchange, Inc., CN=*.stackexchange.com
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:f4:a9:3a:35:75:0f:d6:87:17:b7:cf:66:4f:57:
                    08:c5:a7:41:87:30:8b:d1:84:ea:3f:4d:7f:0d:2a:
                    2d:50:74:73:57:bd:2a:38:24:fb:01:d3:13:d0:ad:
                    49:8b:aa:c5:c9:aa:73:46:2a:94:22:10:24:84:4b:
                    1e:5d:1a:74:30:da:f6:d5:f4:94:c3:85:68:09:bf:
                    88:98:ee:a0:9c:89:73:a2:59:21:ae:92:ba:23:2d:
                    f8:2b:25:37:cf:2b:7c:5d:80:fe:99:8d:e2:f0:68:
                    cf:64:ec:ac:44:93:4b:cb:7a:2e:40:19:b3:b8:e9:
                    94:ff:61:68:9a:79:a2:10:61:74:da:65:60:6f:77:
                    af:f0:fa:dc:9e:de:dd:0a:21:7b:96:20:48:b1:dd:
                    f3:90:f7:97:bd:35:58:71:57:1b:fc:c0:6b:14:4c:
                    dc:e0:5b:88:ba:98:53:88:96:e8:37:3f:30:1e:ff:
                    7e:3d:70:17:51:41:fc:4c:44:ab:51:f1:4f:08:a2:
                    47:c1:df:44:02:83:57:f2:33:d4:d5:32:31:88:2a:
                    1e:e9:73:79:13:59:8f:c8:68:32:bc:49:da:70:7f:
                    c7:7a:b2:bf:78:b7:38:e8:be:d8:59:51:91:ca:31:
                    d6:69:a4:ca:d2:b2:61:2a:09:21:e7:da:ac:58:17:
                    67:e7
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Authority Key Identifier:
                keyid:51:68:FF:90:AF:02:07:75:3C:CC:D9:65:64:62:A2:12:B8:59:72:3B

            X509v3 Subject Key Identifier:
                9A:8A:C1:6E:C1:F2:4D:FA:D9:7B:02:D4:8F:B3:03:AC:6A:3D:C6:58
            X509v3 Subject Alternative Name:
                DNS:*.stackexchange.com, DNS:stackexchange.com, DNS:stackoverflow.com, DNS:*.stackoverflow.com, DNS:stackauth.com, DNS:sstatic.net, DNS:*.sstatic.net, DNS:serverfault.com, DNS:*.serverfault.com, DNS:superuser.com, DNS:*.superuser.com, DNS:stackapps.com, DNS:openid.stackauth.com, DNS:*.meta.stackexchange.com, DNS:meta.stackexchange.com, DNS:mathoverflow.net, DNS:*.mathoverflow.net, DNS:askubuntu.com, DNS:*.askubuntu.com, DNS:stacksnippets.net, DNS:*.blogoverflow.com, DNS:blogoverflow.com, DNS:*.meta.stackoverflow.com, DNS:*.stackoverflow.email, DNS:stackoverflow.email, DNS:stackoverflow.blog
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Extended Key Usage:
                TLS Web Server Authentication, TLS Web Client Authentication
            X509v3 CRL Distribution Points:

                Full Name:
                  URI:http://crl3.digicert.com/sha2-ha-server-g6.crl

                Full Name:
                  URI:http://crl4.digicert.com/sha2-ha-server-g6.crl

            X509v3 Certificate Policies:
                Policy: 2.16.840.1.114412.1.1
                  CPS: https://www.digicert.com/CPS
                Policy: 2.23.140.1.2.2

            Authority Information Access:
                OCSP - URI:http://ocsp.digicert.com
                CA Issuers - URI:http://cacerts.digicert.com/DigiCertSHA2HighAssuranceServerCA.crt

            X509v3 Basic Constraints: critical
                CA:FALSE
            CT Precertificate SCTs:
                Signed Certificate Timestamp:
                    Version   : v1(0)
                    Log ID    : A4:B9:09:90:B4:18:58:14:87:BB:13:A2:CC:67:70:0A:
                                3C:35:98:04:F9:1B:DF:B8:E3:77:CD:0E:C8:0D:DC:10
                    Timestamp : Oct  5 02:24:01.827 2018 GMT
                    Extensions: none
                    Signature : ecdsa-with-SHA256
                                30:46:02:21:00:F0:9A:77:1B:F8:ED:C0:78:40:E3:AF:
                                37:DB:3F:47:6D:C4:7A:91:1B:48:8E:3F:32:E0:1D:7F:
                                9B:CA:79:4E:FD:02:21:00:DA:06:77:3B:C9:F3:B9:45:
                                5A:9D:15:BD:7E:0E:A6:81:FB:0B:D3:C3:67:FD:91:A6:
                                EF:73:BF:17:72:06:5F:65
                Signed Certificate Timestamp:
                    Version   : v1(0)
                    Log ID    : 87:75:BF:E7:59:7C:F8:8C:43:99:5F:BD:F3:6E:FF:56:
                                8D:47:56:36:FF:4A:B5:60:C1:B4:EA:FF:5E:A0:83:0F
                    Timestamp : Oct  5 02:24:02.054 2018 GMT
                    Extensions: none
                    Signature : ecdsa-with-SHA256
                                30:46:02:21:00:D0:8D:F9:95:06:AF:BF:CB:68:01:2B:
                                F7:84:F7:1E:A3:CF:D8:53:67:9B:48:7E:19:12:B5:2F:
                                39:7C:C0:31:7A:02:21:00:C0:2E:36:4C:AE:3B:8B:74:
                                E8:48:84:80:C5:A2:6A:52:59:B8:09:E4:43:0D:BD:19:
                                C7:88:04:6F:2B:D4:0A:77
    Signature Algorithm: sha256WithRSAEncryption
         00:93:ce:f7:ff:ed:90:b3:02:9f:25:24:27:fa:26:5e:65:cf:
         2e:88:68:3d:f6:99:9d:d3:4f:04:d9:c9:86:12:ba:8d:cc:f7:
         25:2b:d2:0d:6c:f8:f0:c6:5f:73:22:04:dc:5e:91:7f:52:d0:
         55:55:2d:59:ed:7a:3c:de:a7:ec:18:c3:dd:33:36:2d:dc:5f:
         a1:42:94:18:2e:19:46:17:ee:49:7f:6c:7a:65:bd:73:8d:3f:
         da:33:71:8c:74:68:be:e8:e3:d5:f9:81:e5:ff:08:14:7b:8e:
         4d:ea:44:6e:0d:99:d5:2f:5e:bb:f9:6d:e5:da:70:fe:99:28:
         4e:ff:bc:6a:c0:78:99:bb:3d:06:1f:20:47:46:9e:62:e3:76:
         e5:1f:4b:e0:eb:bb:09:f2:0b:8d:f3:5a:5a:a6:ea:58:da:fe:
         fc:15:cb:d1:f2:3d:04:2d:f8:32:7a:1b:56:a6:31:77:bf:32:
         92:ab:fa:d8:da:c3:17:4d:8c:d2:3e:a3:1e:92:cb:1e:1c:d8:
         52:31:85:3a:5b:0f:61:f6:9c:8c:69:59:f0:f6:f6:a1:a9:fe:
         e7:28:71:dc:0b:65:51:4d:48:24:41:f9:fd:c8:39:a6:04:ea:
         34:9d:0f:17:81:fa:5d:eb:9f:cf:6b:15:5f:06:7b:8a:7c:49:
         17:05:fa:4c

    这是假设一个 PEM 格式的证书，对于二进制格式，您可以添加-inform DER，检查使用哪个可以使用file命令执行，通常存在于 Linux 和 Cygwin（如果安装正确）。

    我个人不一定信任文件扩展名。文件扩展名错误太容易了，文件扩展名是一种非常宽松的打字系统。

    好的，现在您已经验证该文件是关于结构的 X.509 证书。但是，您可能还想验证证书链直至可信证书。您可能还想执行其他验证，例如检查证书在正确的日期是否仍然有效。这是有关如何执行此操作的指南。

    为了完全完整，您可能还想检查 OCSP 状态，看看证书颁发机构 (CA) 是否吊销了证书。

    如果证书可以由对手生成，或者因为它是由公司中的一位开发人员生成的（自签名）测试证书，那么您肯定需要这个。

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