用gpg(Gnu 隐私卫士)来生成自己的密钥
回家折腾建立ubuntu本地源，这个很有用，特别是在上网算流量的学校用linux，方法主要参照这个wiki页面：
http://wiki.ubuntu.org.cn/使用apt-move创建软件库光盘
root@ubuntu:/mirrors/debian# gpg -bao dists/karmic/Release.gpg dists/karmic/Release
gpg: directory `/home/tun/.gnupg' created
gpg: new configuration file `/home/tun/.gnupg/gpg.conf' created
gpg: WARNING: options in `/home/tun/.gnupg/gpg.conf' are not yet active during this run
gpg: keyring `/home/tun/.gnupg/secring.gpg' created
gpg: keyring `/home/tun/.gnupg/pubring.gpg' created
gpg: no default secret key: secret key not available
gpg: signing failed: secret key not available
当执行以上蓝色字体的命令的时候出错了。这个命令功能是生成Release文件的gpg密钥。从字面意思来理解应该是gpg没有默认的gpg密钥, 参照这个minihowto: Gnu 隐私卫士 (GnuPG) 袖珍 HOWTO (中文版) 发现可以用gpg –gen-key来生成自己的密钥：（蓝色字体是我输入的）
root@ubuntu:/mirrors/debian# gpg –gen-key
gpg (GnuPG) 1.4.9; Copyright (C) 2008 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Please select what kind of key you want:
(1) DSA and Elgamal (default)
(2) DSA (sign only)
(5) RSA (sign only)
Your selection? 1
DSA keypair will have 1024 bits.
ELG-E keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) （直接回车）
Requested keysize is 2048 bits
Please specify how long the key should be valid.
0 = key does not expire
Key is valid for? (0) （直接回车）
Key does not expire at all
Is this correct? (y/N) y
You need a user ID to identify your key; the software constructs the user ID
from the Real Name, Comment and Email Address in this form:
"Heinrich Heine (Der Dichter)
Real name: tunpishuang
Email address: [email protected]
Comment: just 4 fun.
You selected this USER-ID:
"tunpishuang (just 4 fun.)
Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
You need a Passphrase to protect your secret key.
gpg: gpg-agent is not available in this session
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
++++++++++++++++++++++++++++++.+++++.++++++++++++++++++++++++++++++.++++++++++++++++++++++++++++++.+++++++++++++++++++++++++.+++++.+++++>+++++.+++++……………..>+++++…+++++
ds
Not enough random bytes available. Please do some other work to give
the OS a chance to collect more entropy! (Need 283 more bytes)
We need to generate a lot of random bytes. It is a good idea to perform
some other action (type on the keyboard, move the mouse, utilize the
disks) during the prime generation; this gives the random number
generator a better chance to gain enough entropy.
+++++…++++++++++..++++++++++.++++++++++..+++++++++++++++..+++++…++++++++++++++++++++.+++++++++++++++++++++++++.+++++..++++++++++++++++++++++++++++++…+++++..+++++>…++++++++++>+++++.>.+++++……<.+++++……………..<+++++>..+++++…………………………………………………………………………………………………………………………………………..<+++++…>+++++…………………………………..+++++^^^^^^^^^
（上面这一砣蓝字的主要意思是通过移动鼠标和写入/输出硬盘数据来生成随机数字，我一般使用du / 命令）
gpg: key EDA38ECC marked as ultimately trusted
public and secret key created and signed.
gpg: checking the trustdb
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u
pub 1024D/EDA38ECC 2009-08-20
Key fingerprint = 8B43 BB97 2716 0124 83C5 D73B DEE3 732F EDA3 8ECC
uid tunpishuang (just 4 fun.)
sub 2048g/15197563 2009-08-20
root@ubuntu:/mirrors/debian# gpg –list-keys （生成成功了）
/home/tun/.gnupg/pubring.gpg
—————————-
pub 1024D/EDA38ECC 2009-08-20
uid tunpishuang (just 4 fun.)
sub 2048g/15197563 2009-08-20
root@ubuntu:/mirrors/debian# apt-key list （通过这个我们发现改gpg的key和apt的key不是一个库的，但是可以通过gpg导入到apt-key中）
/etc/apt/trusted.gpg
——————–
pub 1024D/437D05B5 2004-09-12
uid Ubuntu Archive Automatic Signing Key
sub 2048g/79164387 2004-09-12
pub 1024D/FBB75451 2004-12-30
uid Ubuntu CD Image Automatic Signing Key
root@ubuntu:/mirrors/debian# gpg -bao dists/karmic/Release.gpg dists/karmic/Release （执行成功）
You need a passphrase to unlock the secret key for （这点输入私人密钥就ok）
user: "tunpishuang (just 4 fun.)
1024-bit DSA key, ID EDA38ECC, created 2009-08-20
gpg: gpg-agent is not available in this session