去掉密钥口令加密

$ gpg --edit-key <user_id>
gnupg> passwd
Enter passphrase: *****
new passphrase:
reenter passphrase:
Are you sure you want to remove your passphrase? Y
gnupg> save

导出密钥

$ gpg --export-secret-keys --armor --no-comment --output bad.asc

重新为密钥加上口令

$ gpg --edit <user_id>
   gnupg> passwd
   You have no passphrase!
   new passphrase: *****
   reenter passphrase: *****
   gnupg> save

密钥导入到PGP

import bad.asc into PGP.

$ pgp -ka bad.asc

删除临时文件

$ pgp -w bad.asc

	'-w' means safely wipe file. It is better than using rm.

为导入到PGP的KEY设置为绝对信任（implicit trust/ an ultimately-trusted introducer）。

$ pgp -ke <userid>

为PGP的密钥加入口令保护。

$ pgp -ke <userid>