HTTPS自己生成数字证书

一、获取证书的途径

1. 自签名证书，适用于开发者测试HTTPS，最快速的途径就是生成自签名证书，非常方便。
2. Let's Encrypt证书，可以使用免费CA机构签发的证书。
3. 使用收费CA机构签发的证书，如果对证书安全性、兼容性、功能有特殊需求，可以向CA机构申请证书。

二、自签名证书

自签名证书是我们自己签发的，浏览器不会集成私有的CA机构的根证书，所以打开页面的时候会进行提示，用户选择信任证书之后，后续的通信就会进行加密保护的。

自签名证书的用途还是很广泛的，对于一些企业内部系统，由于购买证书需要成本，可以生成自签名证书，企业内部系统的用户一般运行在同一个局域网下，由防火墙保护，风险相对可控，当浏览器提示用户自签名证书存在风险时，用户可以选择信任自签名证书，等同于访问了一个HTTPS网站。

生成自签名证书的步骤如下

1.生成私钥对和CSR

我们设置密钥的长度为2048bit；

我们最终会得到flask_self_csr.pem和flask_self_key.pem两个文件;

CSR(Certificate Signing Request)表示证书签名请求，里面包含了服务器的密钥对，CA机构接收到请求会验证CSR请求的签名；

flask_self_csr.pem包含了我们的密钥对；

执行命令之后，我们可以在交互式提示中，设置证书包含的一些信息；

mango@mango-ubuntu:~/文档/blogs/web/证书$ openssl req  -newkey rsa:2048 -nodes -keyout flask_self_key.pem  -out flask_self_csr.pem
Generating a RSA private key
.........+++++
......+++++
writing new private key to 'flask_self_key.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:CN
State or Province Name (full name) [Some-State]:Beijing
Locality Name (eg, city) []:Beijing
Organization Name (eg, company) [Internet Widgits Pty Ltd]:mango
Organizational Unit Name (eg, section) []:mango
Common Name (e.g. server FQDN or YOUR name) []:cee1-110-251-30-176.ngrok.io
Email Address []:mango@163.com

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:          
An optional company name []:

2. 生成自签名证书

接下来通过CSR生成证书，对于自签名证书，我们可以认为自己就是一个CA机构，输入如下命令生成证书：

mango@mango-ubuntu:~/文档/blogs/web/证书$ openssl x509 -signkey flask_self_key.pem -in flask_self_csr.pem  -req -days 365 -out flask_self_cert.pem
Signature ok
subject=C = CN, ST = Beijing, L = Beijing, O = mango, OU = mango, CN = cee1-110-251-30-176.ngrok.io, emailAddress = mango@163.com
Getting Private key

3. 验证证书

将生成的flask_self_cert.pem和flask_self_key.pem拷贝到站点根目录下，并设置启用ssl

from flask import Flask


app = Flask(__name__)

@app.route("/", methods=["GET"])
def hello():
    return 'hello python'

if __name__ == "__main__":
    app.run('0.0.0.0', ssl_context=('flask_self_cert.pem', 'flask_self_key.pem'))
    # app.run('0.0.0.0', debug=True, ssl_context='adhoc')

三、使用Let's Encrypt证书

Let's Encrypt首先是一个CA机构，得到了很多大公司的支持，兼容性非常不错，同时它定义了ACME协议，将管理证书的流程进行了标准化、自动化，不用人工管理。可以使用基于ACME协议的客户端在Let's Encrypt管理证书，官方推荐Certbot客户端，使用非常方便。

1.安装Certbot客户端

mango@mango-ubuntu:~/文档/blogs/web/证书/certbot$ sudo snap install --classic certbot
certbot 1.21.0 from Certbot Project (certbot-eff✓) installed

2.手动生成证书和密钥文件

mango@mango-ubuntu:~/文档/blogs/web/证书$ sudo certbot certonly --manual  -d 565c-110-251-30-176.ngrok.io 
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Requesting a certificate for 565c-110-251-30-176.ngrok.io

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Create a file containing just this data:

csM3J5YGt3V-PQDeRpcDhjlpy7Hdf9tjh-NsIqqoA6A.eRfiNKPaGpDq-g1FefRl52GbfFeSDV_Qg8Gwe1KQP5M

And make it available on your web server at this URL:

http://565c-110-251-30-176.ngrok.io/.well-known/acme-challenge/csM3J5YGt3V-PQDeRpcDhjlpy7Hdf9tjh-NsIqqoA6A

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Press Enter to Continue

Successfully received certificate.
Certificate is saved at: /etc/letsencrypt/live/565c-110-251-30-176.ngrok.io/fullchain.pem
Key is saved at:         /etc/letsencrypt/live/565c-110-251-30-176.ngrok.io/privkey.pem
This certificate expires on 2022-02-10.
These files will be updated when the certificate renews.

NEXT STEPS:
- This certificate will not be renewed automatically. Autorenewal of --manual certificates requires the use of an authentication hook script (--manual-auth-hook) but one was not provided. To renew this certificate, repeat this same certbot command before the certificate's expiry date.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
If you like Certbot, please consider supporting our work by:
 * Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
 * Donating to EFF:                    https://eff.org/donate-le
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

为了通过CA对站点的验证，我们需要新增对应的action来响应对应的请求

@app.route("/.well-known/acme-challenge/csM3J5YGt3V-PQDeRpcDhjlpy7Hdf9tjh-NsIqqoA6A")
def challenge():
    return 'csM3J5YGt3V-PQDeRpcDhjlpy7Hdf9tjh-NsIqqoA6A.eRfiNKPaGpDq-g1FefRl52GbfFeSDV_Qg8Gwe1KQP5M'

3. 验证证书

将生成的证书和密钥文件拷贝到站点根目录，并修改文件权限

mango@mango-ubuntu:~/文档/blogs/webhook$ sudo cp /etc/letsencrypt/live/565c-110-251-30-176.ngrok.io/fullchain.pem fullchain.pem
mango@mango-ubuntu:~/文档/blogs/webhook$ sudo cp /etc/letsencrypt/live/565c-110-251-30-176.ngrok.io/privkey.pem 
mango@mango-ubuntu:~/文档/blogs/webhook$ sudo chown mango fullchain.pem
mango@mango-ubuntu:~/文档/blogs/webhook$ sudo chown mango privkey.pem 

修改站点启用ssl

from flask import Flask

app = Flask(__name__)

@app.route("/", methods=["GET"])
def hello():
    return 'hello python'

@app.route("/.well-known/acme-challenge/csM3J5YGt3V-PQDeRpcDhjlpy7Hdf9tjh-NsIqqoA6A")
def challenge():
    return 'csM3J5YGt3V-PQDeRpcDhjlpy7Hdf9tjh-NsIqqoA6A.eRfiNKPaGpDq-g1FefRl52GbfFeSDV_Qg8Gwe1KQP5M'

if __name__ == "__main__":
    app.run('0.0.0.0', ssl_context=('fullchain.pem', 'privkey.pem'))
    # app.run('0.0.0.0', ssl_context=('flask_self_cert.pem', 'flask_self_key.pem'))
    # app.run('0.0.0.0', debug=True, ssl_context='adhoc')