以匯入的公鑰加密

1. 以 key id 907CE30E 公鑰加密。

   [deyu1@kvm8 ~]$ gpg --output demo.dyw.gpg --encrypt --recipient dywang7@gamil.com demo.txt 
   gpg: 26F7F452: There is no assurance this key belongs to the named user
   
   pub  2048R/26F7F452 2013-06-20 De-Yu Wang (rhcx) <dywang7@gamil.com>
    Primary key fingerprint: C6DA 8C49 D1C5 ED1C 9029  C170 01A0 B0F1 907C E30E
         Subkey fingerprint: FF88 0E58 B9E7 A426 1349  85C7 238F 64EA 26F7 F452
   
   It is NOT certain that the key belongs to the person named
   in the user ID.  If you *really* know what you are doing,
   you may answer the next question with yes.
   
   Use this key anyway? (y/N) y
   

2. 查看產生的加密檔。

   [deyu1@kvm8 ~]$ ll demo.dyw.gpg 
   -rw-r--r--. 1 root root 347 Jun  5 11:13 demo.dyw.gpg
   

3. 將加密檔寄給接收者。

   [deyu1@kvm8 ~]$ scp demo.dyw.gpg dywang@192.168.122.1:Documents/latex/rhcx
   

4. 解密加密檔，出現錯誤訊息，因無法顯示輸入 passphrase 的類視窗。

   [dywang@dywhd2 rhcx]$ gpg --decrypt demo.dyw.gpg 
   
   You need a passphrase to unlock the secret key for
   user: "De-Yu Wang (rhcx) <dywang7@gamil.com>"
   2048-bit RSA key, ID 26F7F452, created 2013-06-20 (main key ID 907CE30E)
   
   gpg: problem with the agent: No pinentry
   gpg: encrypted with 2048-bit RSA key, ID 26F7F452, created 2013-06-20
         "De-Yu Wang (rhcx) <dywang7@gamil.com>"
   gpg: public key decryption failed: General error
   gpg: decryption failed: No secret key
   

5. 刪除 DISPLAY 變數。

   [dywang@dywhd2 rhcx]$ unset DISPLAY
   

6. 再解密加密檔，出現輸入 passphrase 的類視窗，輸入密碼後即可解密。

   [dywang@dywhd2 rhcx]$ gpg --decrypt demo.dyw.gpg 
   ┌───────────────────────────────────────────────────────────────────────┐
   │ Please enter the passphrase to unlock the secret key for the OpenPGP  │
   │ certificate:                                                          │
   │ "De-Yu Wang (rhcx) <dywang7@gamil.com>"                               │
   │ 2048-bit RSA key, ID 26F7F452,                                        │
   │ created 2013-06-20 (main key ID 907CE30E).                            │
   │                                                                       │
   │                                                                       │
   │ Passphrase __________________________________________________________ │
   │                                                                       │
   │          <OK>                                         <Cancel>	   │
   └───────────────────────────────────────────────────────────────────────┘
   
   You need a passphrase to unlock the secret key for
   user: "De-Yu Wang (rhcx) <dywang7@gamil.com>"
   2048-bit RSA key, ID 26F7F452, created 2013-06-20 (main key ID 907CE30E)
   
   gpg: Invalid passphrase; please try again ...
   
   You need a passphrase to unlock the secret key for
   user: "De-Yu Wang (rhcx) <dywang7@gamil.com>"
   2048-bit RSA key, ID 26F7F452, created 2013-06-20 (main key ID 907CE30E)
   
   gpg: encrypted with 2048-bit RSA key, ID 26F7F452, created 2013-06-20
         "De-Yu Wang (rhcx) <dywang7@gamil.com>"
   abc123