add PPA GPG key

$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 9D1A0061

References :
[SOLVED] how to add the PPA key

GPG Key 簽署流程

撤銷 GPG key

妥善保護您密匙固然最重要，但您也要為萬一不幸的事作預備。一般的做法是您要事前先產生一個撤銷憑證 (Revoke Certificate) ，當您的 GnuPG 密匙不幸被盜去或遺失了後，您就可以用這撤銷憑證 去宣告原先的 GnuPG 鑰匙無效。 



# 產生撤銷憑證

$ gpg --output ~/myrevoke.asc --gen-revoke your_user_id

# 撤銷 GPG key

$ gpg --import ~/myrevoke.asc

$ gpg --keyserver pgp.mit.edu --send-keys your_user_id 

References :
產生 GnuPG 撤銷憑證 (Revoke Certificate) - FlossDoc
Revoking a GPG Key Pair | Carthik Sharma

GPG key 過期處理

$ gpg --list-keys
pub 4096R/ABCD1234 2013-09-26 [expired: 2013-12-31]

$ gpg --edit-key ABCD1234

gpg> list

pub 4096R/ABCD1234 created: 2013-09-26 expired: 2013-12-31 usage: SC
trust: unknown validity: expired
sub 4096R/EFGH5678 created: 2013-09-26 expired: never usage: E

gpg> key 0    # 只選擇 primary key，取消選擇 sub key

gpg> expire
Changing expiration time for the primary key.
Please specify how long the key should be valid.
0 = key does not expire
= key expires in n days
w = key expires in n weeks
m = key expires in n months
y = key expires in n years
Key is valid for? (0) 2014-12-31    # 可輸入到期日期
Key expires at Wed Dec 31 00:00:00 2014 CST
Is this correct? (y/N) y

gpg> save

$ gpg --keyserver keys.gnupg.net --send-keys ABCD1234

References :

How to change the expiration date of a GPG key | G-Loaded Journal

GPG Keysigning 步驟

 



References :
Keysigning - Debian Wiki

W: GPG error: http://us.archive.ubuntu.com precise Release: The following signatures were invalid: BADSIG 40976EAF437D05B5 Ubuntu Archive Automatic Signing Key

# apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 40976EAF437D05B5

# cd /var/lib/apt
# mv lists lists.old
# mkdir -p lists/partial
# apt-get update