數位簽章-pdf檔

1. 對 demo.pdf 進行數位簽章，輸入 passphrase。

   [dywang@dywmac ~]$ gpg --sign --output=demo.pdf.sig demo.pdf
   
   You need a passphrase to unlock the secret key for
   user: "De-Yu Wang (rhcx) <dywang7@gamil.com>"
   2048-bit RSA key, ID 907CE30E, created 2013-06-20
   
   can't connect to `/home/dywang/.gnupg/S.gpg-agent': 
   No such file or directory
   
   (pinentry-gtk-2:9349): GLib-GObject-CRITICAL **: 
   Object class GtkSecureEntry doesn't implement property 
   'editing-canceled' from interface 'GtkCellEditable'
   

2. 產生 demo.pdf.sig。

   [dywang@dywmac ~]$ ll demo.pdf*
   -rw-rw-r--. 1 dywang dywang 1574142 May 31 18:59 demo.pdf
   -rw-rw-r--. 1 dywang dywang 1574045 May 31 19:09 demo.pdf.sig
   

3. 驗證 demo.pdf.sig 為 De-Yu Wang 簽章。

   [dywang@dywmac ~]$ gpg --verify demo.pdf.sig 
   gpg: Signature made Thu 31 May 2018 07:09:51 PM CST using RSA key ID 907CE30E
   gpg: Good signature from "De-Yu Wang (rhcx) <dywang7@gamil.com>"
   

4. 解密 demo.pdf.sig，存成 a.pdf。

   [dywang@dywmac ~]$ gpg --output a.pdf --decrypt demo.pdf.sig 
   gpg: Signature made Thu 31 May 2018 07:09:51 PM CST using RSA key ID 907CE30E
   gpg: Good signature from "De-Yu Wang (rhcx) <dywang7@gamil.com>"
   

5. 比對 a.pdf 與原始檔 demo.pdf 無差異。

   [dywang@dywmac ~]$ diff demo.pdf a.pdf