This document provides an overview of RSA encryption/decryption and related concepts. It discusses how to implement RSA in PHP, Android, Python and C# with examples of encrypting and decrypting text. It also lists common file extensions used in RSA, padding types, encoding formats like DER and PEM, and cryptography standards like PKCS #1. Finally it provides links to additional RSA resources and questions around key usage.

1. RSA Overview

3. 實作

4. RSA encrypt/ encrypt
rsa encrypt
• Get public’s key
• RSA’s Encrypt
• Base64’s Encode
rsa decrypt
• get private’s key
• Base64’s Decode
• RSA’s Decrypt

5. By PHP
• // rsa encrypt
• openssl_public_encrypt($text, $ encrypt _text, $public_key,
OPENSSL_PKCS1_OAEP_PADDING);
• $encrypted = base64_encode($encrypted);
• echo $encrypted;
• // rsa decrypt
• $encrypted = base64_decode($encrypted);
• openssl_private_decrypt($encrypted , $decrypted,
$private_key, OPENSSL_PKCS1_OAEP_PADDING);
• echo $decrypted;

6. By Android

7. By Python

8. By C#

9. 為什麼解不開!!!
XXX加密OOO解密

10. 1. http://www.voidcn.com/article/p-wqfbjkpx-
bky.html
2. https://ifun01.com/8RECSF4.html
3. https://my.oschina.net/u/566591/blog/309771
4. https://blog.csdn.net/mshootingstar/article/det
ails/56496719

11. 相關名詞

12. 編碼方式
• DER
– 二進位格式
• PEM
– 將DER進行base 64 encode

13. PKCS(Public Key Cryptography Standards)
• PKCS #1
– RSA Cryptography Standard
– version 2.1
• PKCS #8
– Private-Key Information Syntax Standard
– version 1.2

14. 副檔名
• .CRT
• .CER
• .KEY
===========我是分隔線===========
• .CSR
• .PFX/.P12
• .p7b
• .JKS

15. provider
• BC - bouncy castle
• JCE - Java Cryptography Extension

16. 相同明文會產生相同密文?

17. PADDING
• RSA_NO_PADDING
• RSA_PKCS1_PADDING
• RSA_PKCS1_OAEP_PADDING
• RSA_SSLV23_PADDING