當商業檔案如 EDI (850,860,810...) 在 FTP 協定中傳輸時,若被別人截取,那資料就會外洩。若能在傳輸前先加密,到客戶端時再作解密,這就保險多了。檔案加解密的軟體很,GnuPG (GPG) 是一套完全免費的軟體( GnuPG is the GNU project's complete and free implementation of the OpenPGP standard as defined by RFC4880 . ),也有在實務的商務中使用,安全性很高值得一用。

GnuPG 概念:

GPG, like PGP (Pretty Good Privacy), uses a key pair. This means that when you generate a key, you will create a public copy as well as private copy. The private copy is your copy used to decrypt an incoming file as well sign an outgoing file (but for our purposes, we are only using it to decrypt). The public key is the key you give to the public, which is used to encrypt the files coming to you. First we will create your own key.
 
These keys are stored in key rings. For GPG, they are stored in the directory that the GPG files were copied into. They are both named with a .GPG extension, and are called pubring.GPG and secring.GPG (to denote the public key ring and the private key ring, respectively).

原文的意思主要是說:GPG 會產生一組 Key ,一個是私鑰 ( Private Key:secring.GPG ) 用來解碼檔案,以及傳出檔案時作簽章 ( sign );一個是公鑰( Public Key:pubring.GPG )是要給客戶的,當客戶要傳檔案給你時,用此公鑰作加密。兩個檔案都是以 .GPG 作為附檔名。

GnuPG 實作:

  那要如何建立這一組Key:私鑰 ( Private Key:secring.GPG )& 公鑰( Public Key:pubring.GPG ),下面一個步驟一個步聚來作解說:

step 01: 環境設定

先到 GnuPG 的下載網站: 下載軟體 gnupg-w32cli-1.2.0.zip. (ftp://ftp.gnupg.org/GnuPG/binary/gnupg-w32cli-1.2.0.zip),這裡使用gnupg-w32cli-1.2.0 版。在 Windows 平台,可以用 7Z 解壓,並將解開的目錄放在 C:\gnupg

再到 開始(Start) > 控制(Control Panel) > 系統(System). 選擇 進階(Advanced tab) 並編輯環境變數中的 Path 參數。

EnvironmentVariables  

step 02: 產生私鑰 ( Private Key:secring.GPG )& 公鑰( Public Key:pubring.GPG )

C:\gnupg> c:\gnupg\gpg --gen-key
gpg (GnuPG) 1.2.0; Copyright (C) 2002 Free Software Foundation, Inc.
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions. See the file COPYING for details.

gpg: keyring `c:/gnupg\secring.gpg' created
gpg: keyring `c:/gnupg\pubring.gpg' created
Please select what kind of key you want:
   (1) DSA and ElGamal (default) <= 選擇預設即可
   (2) DSA (sign only)
   (5) RSA (sign only)
Your selection?
DSA keypair will have 1024 bits.

About to generate a new ELG-E keypair.
              minimum keysize is  768 bits
              default keysize is 1024 bits
    highest suggested keysize is 2048 bits
What keysize do you want? (1024) 2048 <= 輸入 2048
Requested keysize is 2048 bits

Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 10y <= 有效時間10年, 若為0則不失效
Key expires at 06/09/23 10:01:10
Is this correct (y/n)? y <=輸入y表示正確無誤

You need a User-ID to identify your key; the software constructs the user id
from Real Name, Comment and Email Address in this form:
    "Heinrich Heine (Der Dichter) <heinrichh@duesseldorf.de>"

Real name: polin.wei <=這是 USER-ID 作加/解密時要指定用的
Email address: polin.wei@xxx.com
Comment:
You selected this USER-ID:
    "polin.wei <polin.wei@xxx.com>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O <=確定輸入 O
You need a Passphrase to protect your secret key. polin <=保護 Secret key 的密碼

/** 接下來就是產生這一組Key的過程了**/
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.
+++++++++++++++.+++++....++++++++++++++++++++.+++++++++++++++++++++++++.++++++++
++++++++++++.+++++.+++++.++++++++++++++++++++.++++++++++..++++++++++>+++++......
.......>+++++................................................................+++
++
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.
+++++...++++++++++.++++++++++.+++++..+++++..++++++++++.+++++++++++++++++++++++++
+++++.++++++++++.+++++++++++++++++++++++++...++++++++++++++++++++.++++++++++++++
+>..++++++++++.....>..+++++.............................>.+++++....<.+++++......
................................................................................
................................................................................
............................................+++++^^^
gpg: c:/gnupg\trustdb.gpg: trustdb created
public and secret key created and signed.
key marked as ultimately trusted.

/** 下面是這一組Key的資訊 **/
pub  1024D/FBA68168 2013-06-11 polin.wei <polin.wei@xxx.com>
        Key fingerprint = 925A 54A5 03DA 5CFD ECE5  F01C A5DC 98A3 FBA6 8168
sub  2048g/9E6074F7 2013-06-11 [expires: 2023-06-09]

PS: 若要修改secret key Passphrase , 指令如下:

usage: gpg [options] --edit-key user-id [commands]

C:\gnupg>gpg --edit-key polin.wei

gpg (GnuPG) 1.2.0; Copyright (C) 2002 Free Software Foundation, Inc.
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions. See the file COPYING for details.

Secret key is available.

gpg: checking the trustdb
gpg: checking at depth 0 signed=0 ot(-/q/n/m/f/u)=0/0/0/0/0/1
gpg: next trustdb check due at 2023-06-09
pub  1024D/FBA68168  created: 2013-06-11 expires: 2023-06-09 trust: u/u
sub  2048g/9E6074F7  created: 2013-06-11 expires: 2023-06-09
(1). polin.wei <polin.wei@xxx.com>

Command> passwd

Key is protected.

//先輸入原來的密碼

You need a passphrase to unlock the secret key for

user: "polin.wei <polin.wei@xxx.com>"

1024-bit DSA key, ID 53FA0BBC, created 2013-05-23

/**再輸入新的密碼,若連續按兩次 Enter 鍵,則密碼為空,系統會告知this is probably a *bad* idea! **/

Enter the new passphrase for this secret key.

You don't want a passphrase - this is probably a *bad* idea!

Do you really want to do this? yes

step 03: 匯出要給客戶的公鑰

利用 step 02 最後的資訊(如下)來匯出要給客戶的公鑰

/** 下面是這一組Key的資訊 **/
pub  1024D/FBA68168 2013-06-11 polin.wei <polin.wei@xxx.com>
        Key fingerprint = 925A 54A5 03DA 5CFD ECE5  F01C A5DC 98A3 FBA6 8168
sub  2048g/9E6074F7 2013-06-11 [expires: 2023-06-09] <=用這一組來指定 9E6074F7 匯出公鑰

C:\gnupg>gpg --export --output polinwei.asc 9E6074F7

這時會匯出一個檔名為 polinwei.asc 的公鑰,這就是要給客戶匯入用的;當然,客戶也會給你他的公鑰,你也必需匯入進來,並作信認 ( Trust )

 

step 04: 匯入客戶的金鑰( partnerid.asc 此為範例檔),並信認( Trust )

C:\gnupg>gpg --import partnerid.asc <=匯入客戶的金鑰

gpg: key 55FA0BBC: public key "Partner <edi.admin@Partner.com>" imported
gpg: Total number processed: 1
gpg:               imported: 1

 

C:\gnupg>gpg --edit-key 55FA0BBC <=指定要維護那一間客戶
gpg (GnuPG) 1.2.0; Copyright (C) 2002 Free Software Foundation, Inc.
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions. See the file COPYING for details.

gpg: checking the trustdb
gpg: checking at depth 0 signed=0 ot(-/q/n/m/f/u)=0/0/0/0/0/1
gpg: next trustdb check due at 2023-06-09
pub  1024D/55FA0BBC  created: 2013-05-23 expires: 2023-05-21 trust: -/-
sub  2048g/DD28189F  created: 2013-05-23 expires: 2023-05-21
(1). Partner <edi.admin@Partner.com>

Command> trust <= 對此客戶作信認
pub  1024D/55FA0BBC  created: 2013-05-23 expires: 2023-05-21 trust: -/-
sub  2048g/DD28189F  created: 2013-05-23 expires: 2023-05-21
(1). Partner <edi.admin@Partner.com>

Please decide how far you trust this user to correctly
verify other users' keys (by looking at passports,
checking fingerprints from different sources...)?

 1 = Don't know
 2 = I do NOT trust
 3 = I trust marginally
 4 = I trust fully
 5 = I trust ultimately
 m = back to the main menu

Your decision? 5 <= 選擇 5
Do you really want to set this key to ultimate trust? yes

pub  1024D/55FA0BBC  created: 2013-05-23 expires: 2023-05-21 trust: u/-
sub  2048g/DD28189F  created: 2013-05-23 expires: 2023-05-21
(1). Partner <edi.admin@Partner.com>
Please note that the shown key validity is not necessarily correct
unless you restart the program.

Command> quit <=離開

step 05: 檢查客戶的公鑰是否正確存在

C:\gnupg>gpg --list-keys
c:/gnupg\pubring.gpg
--------------------
pub  1024D/FBA68168 2013-06-11 polin.wei <polin.wei@xxx.com>
sub  2048g/9E6074F7 2013-06-11 [expires: 2023-06-09]

pub  1024D/55FA0BBC 2013-05-23 Partner <edi.admin@Partner.com>
sub  2048g/DD28189F 2013-05-23 [expires: 2023-05-21]

 

以上的步驟就是產生一組私鑰 ( Private Key:secring.GPG )& 公鑰( Public Key:pubring.GPG ),與匯出公鑰 polinwei.asc 及匯入客戶公鑰 partnerid.asc 的完整過程。

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