#9 转载：剖析 SSL 证书
TLS 2024-02-27Hello! In my networking zine (which everyone will be able to see soon), there is a page about TLS/SSL (basically this tweet). But as happens when you write 200 words about a thing on a page, there is a lot more interesting stuff to say. So in this post we will dissect an SSL certificates and try to understand it!
你好！ 在我的网络杂志（每个人很快就能看到）中，有一个关于 TLS/SSL 的页面（基本上是这条推文）。 但当你在一页上写下 200 个关于某件事的字时，就会发现有很多更有趣的东西要说。 因此，在这篇文章中，我们将剖析 SSL 证书并尝试理解它！
I am not a security person and I am not going to give you security advice for your website (want to know what TLS ciphers you should use? I have no idea!!!). But! I think it’s interesting to know what it means to “issue a SSL certificate” and I can talk about that a little.
我不是安全人员，我不会为您的网站提供安全建议（想知道您应该使用什么 TLS 密码？我不知道！！！）。 但！ 我认为了解“颁发 SSL 证书”的含义很有趣，我可以稍微讨论一下。
TLS: newer version of SSL
I was confused about what this “TLS” thing was for a long time. Basically newer versions of SSL are called TLS (the version after SSL 3.0 is TLS 1.0). I’m going to just call it “SSL” throughout because that is less confusing to me.
很长一段时间我都对“TLS”这个东西感到困惑。 基本上较新版本的 SSL 称为 TLS（SSL 3.0 之后的版本是 TLS 1.0）。 我将自始至终将其称为“SSL”，因为这对我来说不那么令人困惑。
What’s a certificate?
Suppose I’m checking my email at https://mail.google.com
假设我正在 https://mail.google.com 检查我的电子邮件
mail.google.com is running a HTTPS server on port 443. I want to make sure that I’m actually talking to mail.google.com and not some other random server on the internet owned by EVIL PEOPLE.
“mail.google.com”正在端口 443 上运行 HTTPS 服务器。我想确保我实际上与 mail.google.com 进行通信，而不是与 EVIL PEOPLE 拥有的互联网上的其他随机服务器进行通信 。
This “certificate” business was kind of mysterious to me for a very long time. One day my cool coworker Ray told me that I could connect to a server on the command line and download its certificate!
很长一段时间以来，这个“证书”业务对我来说有点神秘。 有一天，我的酷同事 Ray 告诉我，我可以通过命令行连接到服务器并下载其证书！
(If you want to just look at an SSL certificate, you can click on the green lock in your browser and reliably get all the information you need. But this is more fun.)
（如果您只想查看 SSL 证书，您可以单击浏览器中的绿色锁，可靠地获取您需要的所有信息。但这更有趣。）
So, let’s start by looking at mail.google.com’s certificate and deconstruct it a bit.
那么，让我们首先查看 mail.google.com 的证书并对其进行一些解构。
First, we run openssl s_client -connect mail.google.com:443
首先，我们运行“openssl s_client -connect mail.google.com:443”
This is going to print a bunch of stuff, but we’ll just focus on the certificate. Here, it’s this thing:
这将打印一堆东西，但我们只关注证书。 在这里，就是这个东西：
$ openssl s_client -connect mail.google.com:443
...
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
So far, this is unintelligible nonsense. “MIIElDcca… WHAT?!”
It turns out that this nonsense is a format called “X509”, and the openssl command knows how to decode it.
So I saved this blob of text to a file called cert.pem. You can save it to your computer from this gist if you want to follow along.
Our next mission is to parse this certificate. We do that like this:
到目前为止，这都是难以理解的废话。 “MIIElDcca……什么？！”
原来这个废话是一种叫做“X509”的格式，而openssl命令知道如何解码它。
因此，我将这段文本保存到名为“cert.pem”的文件中。 如果您想继续操作，可以根据此要点将其保存到您的计算机上。
我们的下一个任务是解析此证书。 我们这样做：
$ openssl x509 -in cert.pem -text
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 3633524695565792915 (0x326cdf7599cef693)
Signature Algorithm: sha256WithRSAEncryption
Issuer: C=US, O=Google Inc, CN=Google Internet Authority G2
Validity
Not Before: Jan 18 18:52:11 2017 GMT
Not After : Apr 12 18:50:00 2017 GMT
Subject: C=US, ST=California, L=Mountain View, O=Google Inc, CN=mail.google.com
Subject Public Key Info:
Public Key Algorithm: rsaEncryption
Public-Key: (2048 bit)
Modulus:
00:89:87:2b:0b:d4:67:ee:0f:71:8e:c8:3b:92:1a:
9f:44:fc:54:9e:fa:60:1b:20:87:a8:93:17:c5:91:
.... blah blah blah ............
c2:4e:f8:9d:5f:ff:cf:ba:e3:65:45:95:60:dc:d8:
ca:ff
Exponent: 65537 (0x10001)
X509v3 extensions:
X509v3 Subject Alternative Name:
DNS:mail.google.com, DNS:inbox.google.com
X509v3 Subject Key Identifier:
8E:BD:69:80:84:B5:BD:AC:C1:B2:49:47:77:0C:39:37:5C:7E:F6:78
Signature Algorithm: sha256WithRSAEncryption
21:8a:a4:08:c2:41:a9:d4:d9:a5:2e:af:3d:82:3a:00:7e:9c:
1a:6a:91:ee:46:2c:71:97:64:b9:e1:fc:ae:ff:85:8e:1c:92:
......... blah blah blah more goes here ...........
This is a lot of stuff. Here are the parts of this that I understand
CN=mail.google.comis the “common name”. Counterintuitively you should ignore this field and look at the “subject alternative name” field instead- an expiry date: Apr 12 18:50:00 2017 GMT
- The
X509v3 Subject Alternative Name:section has the list of domains that this certificate works for. This is mail.google.com and inbox.google.com, which makes sense – they’re both email domains. - The
Public Key Infosection tells us the public key that we’re going to use to communicate with mail.google.com. We do not have time to explain public key cryptography right now, but this is basically the encryption key we’re going to use to talk secretly. - Lastly, the signature is a really important thing. Basically anyone could make a certificate for mail.google.com. I could make one right now! But if I gave you that certificate, you would have no reason to believe that it is a real certificate
So let’s talk about certificate signing.
这是很多东西。 这是我理解的部分
CN=mail.google.com是“通用名称”。 与直觉相反，您应该忽略此字段并查看“主题备用名称”字段- 到期日期：2017 年 4 月 12 日 18:50:00 GMT
- “X509v3 使用者备用名称：”部分包含此证书适用的域列表。 这是 mail.google.com 和 inbox.google.com，这是有道理的 – 它们都是电子邮件域。
- “公钥信息”部分告诉我们将用来与 mail.google.com 进行通信的公钥。 我们现在没有时间解释公钥密码学，但这基本上是我们将用来秘密交谈的加密密钥。
- 最后，签名是一件非常重要的事情。 基本上任何人都可以为 mail.google.com 制作证书。 我现在就可以做一个！ 但如果我给你那个证书，你就没有理由相信这是一个真正的证书
那么我们来谈谈证书签名。
certificate signing
Every certificate on the internet is basically two parts put together
- A certificate (the domain name it’s valid for and public key and other stuff)
- A signature by someone else. This basically says, “hey, this is okay, Visa says so”
I have a bunch of certificates on my computer in /etc/ssl/certs. Those are the certificates my computer trusts to sign other certificates. For example, I have /etc/ssl/certs/Staat_der_Nederlanden_EV_Root_CA.pem on my laptop. Some certificate from the Netherlands! Who knows! If they signed a mail.google.com certificate, my computer would be like “yep, looks great, sounds awesome”.
If some random person across the street signed a certificate, my computer would be like “I have no idea who you are”, and reject the certificate.
The mail.google certificate is
- s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=mail.google.com
- which is signed by a “Google Internet Authority G2” certificate
- which is signed by a “GeoTrust Global CA” certificate
- which is signed by an “Equifax Secure Certificate Authority” certificate
I have an /etc/ssl/certs/GeoTrust_Global_CA.pem file on my computer, which I think is why I trust this mail.google.com certificate. (Geotrust signed Google’s certificate, and Google signed mail.google.com)
互联网上的每个证书基本上都是由两部分组合而成
- 证书（有效的域名和公钥等）
- 其他人的签名。 这基本上是在说，“嘿，没关系，Visa 是这么说的”
我的计算机上的 /etc/ssl/certs 中有一堆证书。 这些是我的计算机信任的用于签署其他证书的证书。 例如，我的笔记本电脑上有“/etc/ssl/certs/Staat_der_Nederlanden_EV_Root_CA.pem”。 荷兰的一些证书！ 谁知道！ 如果他们签署了“mail.google.com”证书，我的计算机就会说“是的，看起来很棒，听起来很棒”。
如果街对面的某个随机人签署了证书，我的计算机就会像“我不知道你是谁”一样，并拒绝该证书。
mail.google 证书是
- s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=mail.google.com
- 由“Google Internet Authority G2”证书签名
- 由“GeoTrust Global CA”证书签名
- 由“Equifax 安全证书颁发机构”证书签名
我的计算机上有一个 /etc/ssl/certs/GeoTrust_Global_CA.pem 文件，我认为这就是我信任此 mail.google.com 证书的原因。 （Geotrust 签署了 Google 的证书，Google 签署了 mail.google.com）
what does getting a certificate issued look like?
So when you get a certificate issued, basically how it works is:
- You generate the first half of the certificate (“jvns.ca! expires on X date! This is my public key!”). This part is public.
- At the same time, you generate a private key for you certificate. You keep this very secret and safe and do not show it to anybody. You’ll use this key every time you establish an SSL connection.
- You pay a certificate authority (CA) that other computers trust to sign your certificate for you. Certificate authorities are supposed to have integrity, so they are supposed to actually make sure that when they sign certificates, the person they give the cert to actually owns the domain.
- You configure your website with your signed certificate and use it to prove that you are really you! Success!
This “certificate authorities are supposed to have integrity thing” I think is why people get so mad when there are issues like this with Symantec where they generated test certificates “to unregistered domains and domains for which Symantec did not have authorization from the domain owner”
因此，当您获得颁发的证书时，其工作原理基本上是：
- 您生成证书的前半部分（“jvns.ca！在 X 日期到期！这是我的公钥！”）。 这部分是公开的。
- 同时，您为证书生成私钥。 您将其保密且安全，并且不向任何人展示。 每次建立 SSL 连接时都将使用此密钥。
- 您向其他计算机信任的证书颁发机构 (CA) 付费，由其为您签署证书。 证书颁发机构应该具有完整性，因此他们应该真正确保在签署证书时，他们向其提供证书的人实际上拥有该域。
- 您使用您的签名证书配置您的网站，并用它来证明您确实是您！ 成功！
我认为“证书颁发机构应该保持诚信”，这就是为什么人们在出现[赛门铁克的此类问题](https://www.symantec.com/page.jsp?id=test-certs- 更新），他们为“未注册的域以及赛门铁克未获得域所有者授权的域”生成了测试证书
certificate transparency
The last thing we are going to talk about is certificate transparency. This is a super interesting thing and has a good website and I am almost certainly going to mangle it.
I will try anyway!
So, we said that certificate authorities are “supposed to have integrity”. But there are SO MANY certificate authorities that my computer trusts! And at any time one of them could sign a rogue certificate for mail.google.com. That’s no good.
This isn’t a hypothetical issue – the certificate transparency website talks about more than one instance where a CA has been compromised or otherwise has made a mistake.
So, here’s the deal. At any given time, Google knows all the valid certificates that are supposed to exist for mail.google.com (there is probably only one or something). So certificate transparency is basically a way to make sure that if there is a certificate in circulation for mail.google.com that they DON’T know about, that they can find out.
Here are the steps, as I understand them
- Every time any CA signs a certificate, they are supposed to put into a global public “certificate log”
- Also the Googlebot puts every certificate it finds on the internet into the certificate log
- If a certificate isn’t in the log, then my browser will not accept it (or will stop accepting it in the future or something)
- Anyone can look at the log at any time to find out if there are rogue certificates in there
So if that CA in the Netherlands signs an evil mail.google.com certificate, they either have to put it in the public log (and Google will find out about their evil ways) or leave it out of the public log (and browsers will reject it).
我们要讨论的最后一件事是证书透明度。 这是一件非常有趣的事情，并且有一个很好的网站，我几乎肯定会破坏它。
无论如何我都会尝试！
因此，我们说证书颁发机构“应该具有完整性”。 但是我的计算机信任很多证书颁发机构！ 他们中的任何一个人都可以随时为 mail.google.com 签署一份流氓证书。 那可不行。
这不是一个假设的问题 - 证书透明度 网站讨论了不止一个 CA 已被泄露或以其他方式做出了 错误。
所以，这就是交易。 在任何给定时间，Google 知道“mail.google.com”应存在的所有有效证书（可能只有一个或某项）。 因此，证书透明度基本上是一种确保 mail.google.com 是否有他们不知道的证书在流通的方法，他们可以找到。
据我了解，这是步骤
- 每次任何 CA 签署证书时，他们都应该放入全球公共“证书日志”中
- Googlebot 还将它在互联网上找到的每个证书放入证书日志中
- 如果证书不在中，那么我的浏览器将不会接受它（或者将来会停止接受它或其他什么）
- 任何人都可以随时查看日志，了解其中是否存在流氓证书
因此，如果荷兰的 CA 签署了邪恶的 mail.google.com 证书，他们要么必须将其放入公共日志中（Google 会发现他们的邪恶方式），要么将其从公共日志中删除（浏览器将 拒绝它）。
setting up SSL stuff is hard
Okay! We have downloaded a SSL certificate and dissected it and learned a few things about it. Hopefully some of you have learned something!
Picking the right settings for your SSL certificates and SSL configuration on your webserver is confusing. As far as I understand it there are about 3 billion settings. Here is an example of an SSL Labs result for mail.google.com. There is all this stuff like OLD_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 on that page (for real, that is a real thing.). I’m happy there are tools like SSL Labs that help mortals make sense of all of it.
Someone told me https://cipherli.st/ is a way to pick secure SSL configuration if you’re not sure what to do. I don’t know if it’s good or not.
好的！ 我们已经下载了 SSL 证书并对其进行了剖析并了解了一些有关它的信息。 希望你们中的一些人学到了一些东西！
为 Web 服务器上的 SSL 证书和 SSL 配置选择正确的设置是令人困惑的。 据我了解，大约有 30 亿个设置。 以下是 mail.google.com 的 SSL 实验室结果示例。 该页面上有诸如“OLD_TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256”之类的所有内容（实际上，这是真实的东西。）。 我很高兴有像 SSL Labs 这样的工具可以帮助普通人理解这一切。
有人告诉我，如果您不确定该怎么做，https://cipherli.st/ 是选择安全 SSL 配置的一种方法。 我不知道这好不好。
let’s encrypt is amazing
Also let’s encrypt is really cool! They let you have a certificate for your site and make it secure, and you don’t even need to understand all this stuff about how certificates work on the inside! And it’s FREE.
另外，let’s encrypt 真的很酷！ 它们让您拥有网站的证书并确保其安全，您甚至不需要了解所有有关证书内部工作原理的内容！ 而且它是免费的。
