CSR 是否使用私钥加密？

Question

包含公钥和组织详细信息的 CSR（证书签名请求）是否使用私钥加密？

-如果是，证书颁发机构如何解密它，因为 CSR 中的公钥也被加密了？

-如果没有，CA 如何确定 CSR 颁发者拥有私钥？

Answer 1

CSR 的结构在 PKCS #10 中定义，重新发布为RFC 2986

CSR 包括请求者的公钥等。 CA 需要验证请求者是否持有相应的私钥。为确保私钥的所有权，请求者使用其私钥对 CSR 的数据进行签名。

当 CA 收到 CSR 时，它会提取请求者的公钥并验证签名。如果验证失败，则 CSR 被拒绝。

The Wikipedia page 包含一个具有逐字段分解的示例 CSR。该示例是一个使用 RSA 公钥的证书请求，并使用md5WithRSAEncryption 算法进行签名。

Answer 2

包含公钥和组织详细信息的 CSR（证书签名请求）是否使用私钥加密？

很容易检查它不是。

1) 创建私钥和关联的 CSR：

openssl req -new -sha256 -newkey rsa:2048 -nodes -keyout example.key -out example.csr

2) 我现在有 2 个文件，私钥和 CSR。 让我们展示删除私钥后CSR的内容，以确保不需要它，并与私钥进行比较。

私钥还在：

$ openssl req -noout -text -in example.csr
Certificate Request:
    Data:
        Version: 1 (0x0)
        Subject: C = AU, ST = Some-State, O = Internet Widgits Pty Ltd
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                RSA Public-Key: (2048 bit)
                Modulus:
                    00:e2:23:3c:4e:d8:39:ce:9a:16:2f:e2:ef:e7:9b:
                    5d:7f:20:a7:9a:4b:dd:54:ad:6b:b3:ff:33:78:65:
                    f2:b1:e1:e3:b5:eb:23:9d:da:b3:8d:3c:2f:1f:60:
                    9a:17:36:df:0f:4e:3a:bd:fb:9f:73:d5:00:c2:65:
                    04:a2:77:e6:5b:27:f2:30:8f:57:31:c8:bf:d1:0a:
                    cc:db:f5:95:8e:98:ff:34:c5:ed:68:57:f8:43:47:
                    41:ff:cb:6d:27:ae:de:33:95:cd:d6:0a:f8:0b:25:
                    27:99:4e:6b:7d:d8:c4:dd:83:97:57:7a:42:69:4c:
                    41:e2:d6:7f:86:d0:6f:1b:c2:30:b2:e7:a9:ee:5b:
                    9d:a1:ce:80:ec:45:a6:ad:a4:6e:b1:6a:b1:68:ef:
                    c4:7d:5b:6c:e5:24:fe:54:f9:bb:09:48:5c:49:ca:
                    fe:41:28:bc:48:e8:02:bf:ac:b0:5b:c6:3f:bb:0e:
                    17:d4:31:02:31:27:b1:a3:7a:ff:82:49:f0:11:10:
                    64:53:44:ca:61:82:fd:3a:82:5c:07:48:23:1f:db:
                    e5:0f:64:79:09:19:25:b4:a5:07:42:d3:b4:54:75:
                    61:13:43:63:34:a2:72:55:07:d6:d1:8c:74:31:cb:
                    5c:54:1e:6a:e7:04:86:35:4c:d9:a4:31:3f:fd:36:
                    9c:59
                Exponent: 65537 (0x10001)
        Attributes:
            a0:00
    Signature Algorithm: sha256WithRSAEncryption
         6d:fb:a6:e5:2b:89:5c:ef:5c:ca:cc:d3:9a:3d:b1:c1:41:9d:
         b5:55:ca:2c:17:ca:ea:74:1d:79:b9:16:ec:81:08:95:94:98:
         e1:2b:50:c7:46:eb:d4:97:09:25:cc:da:b4:bd:34:3c:5a:14:
         c8:88:ed:21:99:63:e9:c0:0e:fa:bb:5d:a7:27:11:22:61:a1:
         1f:d3:65:c8:cc:14:ff:d7:ce:19:29:14:67:ed:e5:b8:31:b5:
         25:55:8e:59:42:f1:2a:6d:f9:fe:4a:be:08:b9:23:c5:b6:3b:
         c8:7e:3f:0c:bd:bb:37:f6:fd:5a:0e:50:50:43:8e:59:f7:b6:
         77:06:50:b2:45:2a:17:f4:53:5a:7c:3c:50:6d:de:74:e3:0e:
         df:94:48:bc:a9:fa:b8:a1:9a:3e:dc:10:c8:50:cb:9b:a7:49:
         cc:ac:88:66:54:e6:d3:06:81:95:f4:ac:e1:61:d7:88:18:74:
         e8:8e:d2:8d:e9:71:7f:99:41:b9:b3:a1:ad:af:d6:0b:2f:46:
         8d:fa:c4:29:b4:40:38:fb:80:31:33:5c:62:67:62:dd:62:14:
         36:fe:8f:8d:36:dc:0c:52:7b:0b:46:1c:58:94:2f:84:a9:54:
         b0:a8:78:a0:9d:30:e9:0d:2f:a5:09:7d:3e:4e:75:16:56:f7:
         94:a7:09:8f

现在删除私钥：

rm example.key

并再次解码 CSR：

$ openssl req -noout -text -in example.csr
Certificate Request:
    Data:
        Version: 1 (0x0)
        Subject: C = AU, ST = Some-State, O = Internet Widgits Pty Ltd
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                RSA Public-Key: (2048 bit)
                Modulus:
                    00:e2:23:3c:4e:d8:39:ce:9a:16:2f:e2:ef:e7:9b:
                    5d:7f:20:a7:9a:4b:dd:54:ad:6b:b3:ff:33:78:65:
                    f2:b1:e1:e3:b5:eb:23:9d:da:b3:8d:3c:2f:1f:60:
                    9a:17:36:df:0f:4e:3a:bd:fb:9f:73:d5:00:c2:65:
                    04:a2:77:e6:5b:27:f2:30:8f:57:31:c8:bf:d1:0a:
                    cc:db:f5:95:8e:98:ff:34:c5:ed:68:57:f8:43:47:
                    41:ff:cb:6d:27:ae:de:33:95:cd:d6:0a:f8:0b:25:
                    27:99:4e:6b:7d:d8:c4:dd:83:97:57:7a:42:69:4c:
                    41:e2:d6:7f:86:d0:6f:1b:c2:30:b2:e7:a9:ee:5b:
                    9d:a1:ce:80:ec:45:a6:ad:a4:6e:b1:6a:b1:68:ef:
                    c4:7d:5b:6c:e5:24:fe:54:f9:bb:09:48:5c:49:ca:
                    fe:41:28:bc:48:e8:02:bf:ac:b0:5b:c6:3f:bb:0e:
                    17:d4:31:02:31:27:b1:a3:7a:ff:82:49:f0:11:10:
                    64:53:44:ca:61:82:fd:3a:82:5c:07:48:23:1f:db:
                    e5:0f:64:79:09:19:25:b4:a5:07:42:d3:b4:54:75:
                    61:13:43:63:34:a2:72:55:07:d6:d1:8c:74:31:cb:
                    5c:54:1e:6a:e7:04:86:35:4c:d9:a4:31:3f:fd:36:
                    9c:59
                Exponent: 65537 (0x10001)
        Attributes:
            a0:00
    Signature Algorithm: sha256WithRSAEncryption
         6d:fb:a6:e5:2b:89:5c:ef:5c:ca:cc:d3:9a:3d:b1:c1:41:9d:
         b5:55:ca:2c:17:ca:ea:74:1d:79:b9:16:ec:81:08:95:94:98:
         e1:2b:50:c7:46:eb:d4:97:09:25:cc:da:b4:bd:34:3c:5a:14:
         c8:88:ed:21:99:63:e9:c0:0e:fa:bb:5d:a7:27:11:22:61:a1:
         1f:d3:65:c8:cc:14:ff:d7:ce:19:29:14:67:ed:e5:b8:31:b5:
         25:55:8e:59:42:f1:2a:6d:f9:fe:4a:be:08:b9:23:c5:b6:3b:
         c8:7e:3f:0c:bd:bb:37:f6:fd:5a:0e:50:50:43:8e:59:f7:b6:
         77:06:50:b2:45:2a:17:f4:53:5a:7c:3c:50:6d:de:74:e3:0e:
         df:94:48:bc:a9:fa:b8:a1:9a:3e:dc:10:c8:50:cb:9b:a7:49:
         cc:ac:88:66:54:e6:d3:06:81:95:f4:ac:e1:61:d7:88:18:74:
         e8:8e:d2:8d:e9:71:7f:99:41:b9:b3:a1:ad:af:d6:0b:2f:46:
         8d:fa:c4:29:b4:40:38:fb:80:31:33:5c:62:67:62:dd:62:14:
         36:fe:8f:8d:36:dc:0c:52:7b:0b:46:1c:58:94:2f:84:a9:54:
         b0:a8:78:a0:9d:30:e9:0d:2f:a5:09:7d:3e:4e:75:16:56:f7:
         94:a7:09:8f

结论：结果相同，证明不需要密钥。

当然：

1) 立即看到这一点很简单，因为如果在解码 CSR 时需要密钥，则需要在 openssl 的命令行上指定它（它不会在文件中随机插入）

2) 删除私钥当然是愚蠢的，因为现在如果确实从这个 CSR 中创建了一些证书，那么它是无用的，因为附加的私钥不再存在。