我在 Java 中使用 Apache 的 HTTPClient 并尝试连接到 graph.facebook.com。我收到“SSLPeerUnverifiedException:没有对等证书”错误，所以我猜 Facebook 的 CA 不在默认 keystore 中。所以我需要用我想要信任的所有证书创建自己的 keystore ，是吗？所以我找到了以下获取证书的命令:
echo | openssl s_client -connect graph.facebook.com:443 2>&1 | \
sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > mycert.pem
不知道那里发生了什么，但它似乎奏效了。我将证书添加到 Bouncy CaSTLe 格式的 keystore 中。我使用新的 keystore 创建了一个 SSLSocketFactory，但它仍然不起作用。
我的第一个猜测是，也许我没有链中的所有证书(显然这些东西是链式的)。那么我怎么知道是否涉及所谓的“中间”CA？我如何获取这些证书？我走在正确的轨道上吗？
最佳答案
我终于有时间研究这个了，事实证明这 super 简单!我只缺少 openssl 命令的一个选项:showcerts 选项。以下是获取适用于连接到 Facebook 图片服务器的证书的示例。
注意:我还发现，要对 SSL 连接进行身份验证，您不想在 keystore 中添加要连接的端点的证书。您只需要中间和根证书颁发机构。在某些情况下，只有根 CA，否则您将获得异常。参见 this great blog post了解更多信息。
$ openssl s_client -connect graph.facebook.com:443 -showcerts
CONNECTED(00000003)
depth=2 /C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance EV Root CA
verify error:num=20:unable to get local issuer certificate
verify return:0
---
Certificate chain
0 s:/C=US/ST=California/L=Palo Alto/O=Facebook, Inc./CN=*.facebook.com
i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance CA-3
-----BEGIN CERTIFICATE-----
MIIFgjCCBGqgAwIBAgIQDKKbZcnESGaLDuEaVk6fQjANBgkqhkiG9w0BAQUFADBm
MQswCQYDVQQGEwJVUzEVMBMGA1UEChMMRGlnaUNlcnQgSW5jMRkwFwYDVQQLExB3
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aQBhAGIAaQBsAGkAdAB5ACAAYQBuAGQAIABhAHIAZQAgAGkAbgBjAG8AcgBwAG8A
cgBhAHQAZQBkACAAaABlAHIAZQBpAG4AIABiAHkAIAByAGUAZgBlAHIAZQBuAGMA
ZQAuMB0GA1UdJQQWMBQGCCsGAQUFBwMBBggrBgEFBQcDAjANBgkqhkiG9w0BAQUF
AAOCAQEACOkTIdxMy11+CKrbGNLBSg5xHaTvu/v1wbyn3dO/mf68pPfJnX6ShPYy
4XM4Vk0x4uaFaU4wAGke+nCKGi5dyg0Esg7nemLNKEJaFAJZ9enxZm334lSCeARy
wlDtxULGOFRyGIZZPmbV2eNq5xdU/g3IuBEhL722mTpAye9FU/J8Wsnw54/gANyO
Gzkewigua8ip8Lbs9Cht399yAfbfhUP1DrAm/xEcnHrzPr3cdCtOyJaM6SRPpRqH
ITK5Nc06tat9lXVosSinT3KqydzxBYua9gCFFiR3x3DgZfvXkC6KDdUlDrNcJUub
a1BHnLLP4mxTHL6faAXYd05IxNn/IA==
-----END CERTIFICATE-----
1 s:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance CA-3
i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance EV Root CA
-----BEGIN CERTIFICATE-----
MIIGVTCCBT2gAwIBAgIQCFH5WYFBRcq94CTiEsnCDjANBgkqhkiG9w0BAQUFADBs
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-----END CERTIFICATE-----
2 s:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance EV Root CA
i:/C=US/O=Entrust.net/OU=www.entrust.net/CPS incorp. by ref. (limits liab.)/OU=(c) 1999 Entrust.net Limited/CN=Entrust.net Secure Server Certification Authority
-----BEGIN CERTIFICATE-----
MIIEQjCCA6ugAwIBAgIEQodApTANBgkqhkiG9w0BAQUFADCBwzELMAkGA1UEBhMC
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nXZwC99CcvhPQRFkpdLq/NWvEfQVOGecIKhLd1qRMkIy54Wz3zY=
-----END CERTIFICATE-----
---
Server certificate
subject=/C=US/ST=California/L=Palo Alto/O=Facebook, Inc./CN=*.facebook.com
issuer=/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance CA-3
---
No client certificate CA names sent
---
SSL handshake has read 4285 bytes and written 309 bytes
---
New, TLSv1/SSLv3, Cipher is RC4-MD5
Server public key is 1024 bit
Compression: NONE
Expansion: NONE
SSL-Session:
Protocol : TLSv1
Cipher : RC4-MD5
Session-ID: A2AD56513E9EB36D5E4EC193977882BEEC5EC64D07D8E4310C562CC3A4571913
Session-ID-ctx:
Master-Key: 3AC56DD593C864A17D00B08CEFEDB299607491C5E2ABAFE14E2AABADDC8A734B888CC6389BDBE40782EA5ED6E3EAFE4A
Key-Arg : None
Start Time: 1300747299
Timeout : 300 (sec)
Verify return code: 0 (ok)
---
关于java - 获取链中的所有证书；中间和根，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/5188371/