GnuPG 加密與解密

1. 建立一個測試文件 demo.txt。

   [deyu1@kvm8 ~]$ echo 'abc123' > demo.txt
   [deyu1@kvm8 ~]$ cat demo.txt
   abc123
   

2. 確認簽章

   [deyu1@kvm8 ~]$ gpg --check-sigs
   /home/deyu1/.gnupg/pubring.gpg
   ------------------------------
   pub   2048R/A98B198E 2014-05-26
   uid                  abc123 (ABC) <abc123@csie.cyut.edu.tw>
   sig!3        A98B198E 2014-05-26  abc123 (ABC) <abc123@csie.cyut.edu.tw>
   sub   2048R/C039E2B6 2014-05-26
   sig!         A98B198E 2014-05-26  abc123 (ABC) <abc123@csie.cyut.edu.tw>
   

3. 使用 A98B198E 公鑰加密，也就是只有該員可以解密。原始文件 demo.txt，加密後文件 demo.en.txt。

   [deyu1@kvm8 ~]$ gpg --recipient A98B198E --output demo.en.txt --encrypt demo.txt
   

4. 加密後文件 demo.en.txt 已不可讀。

   [deyu1@kvm8 ~]$ cat demo.en.txt
   ...........................................
   

5. 解密使 demo.en.txt，存成 demo.de.txt，必須輸入 passpheasw。

   [deyu1@kvm8 ~]$ gpg --output demo.de.txt --decrypt demo.en.txt
   
   You need a passphrase to unlock the secret key for
   user: "abc123 (ABC) <abc123@csie.cyut.edu.tw>"
   2048-bit RSA key, ID C039E2B6, created 2014-05-26 (main key ID A98B198E)
   
   gpg: encrypted with 2048-bit RSA key, ID C039E2B6, created 2014-05-26
         "abc123 (ABC) <abc123@csie.cyut.edu.tw>"
   

6. 列出解密結果，與原始檔案相同。

   [deyu1@kvm8 ~]$ cat demo.de.txt 
   abc123
   

7. 直接解密 demo.en.txt，會在螢幕上列出解密的結果。

   [deyu1@kvm8 ~]$ gpg --decrypt demo.en.txt
   
   You need a passphrase to unlock the secret key for
   user: "abc123 (ABC) <abc123@csie.cyut.edu.tw>"
   2048-bit RSA key, ID C039E2B6, created 2014-05-26 (main key ID A98B198E)
   
   gpg: encrypted with 2048-bit RSA key, ID C039E2B6, created 2014-05-26
         "abc123 (ABC) <abc123@csie.cyut.edu.tw>"
   abc123