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# System prepended metadata

title: X509 憑證申請

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# X509 憑證申請

## 20240120
Create a self-signed certificate using OpenSSL
https://blog.cssuen.tw/create-a-self-signed-certificate-using-openssl-240c7b0579d3
https://blog.miniasp.com/post/2019/02/25/Creating-Self-signed-Certificate-using-OpenSSL
lets encrypt
https://letsencrypt.org/getting-started/

## 產生金鑰及申請憑證流程
- https://ithelp.ithome.com.tw/articles/10255750?sc=rss.qu
## CA server 及 client 
- 可用多種程式語言及平台建 CA server 及開發 X509 憑證申請 clinet 應用系統
- 建議用 openSSL lib. 建 CA server，並提供 X509 憑證申請 API
- client 程式
## CA server and application client
## chatGPT questions
- 可否提供 openSSL CA  server  申請 X509 憑證之 API 規格範例?
- 可否概述 CSR（Certificate Signing Request）規格?
- 可否提供 Flutter 產生 CSR 的程式範例?