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gnugp

由 datahunter 在 二, 06/12/2011 - 21:08 發表

最後更新: 2020-07-08

目錄

  • 有關檔案
  • 常用選項
  • 使用過程
  • Get Local KeyID
  • Delete Key
  • Export / Import
  • 廢棄證書
  • 上載 Key 到 KeyServer
  • 在 Server 上找別人的 Key
  • 把自己的 Public Key 比別人
  • 簽名與鑑定
  • 檔案的加密與解密
  • web of trust
  • 應用: 在 Mutt 中使用 GnuPG
  • Trust code
  • PGP public key server
  • gpg4win
  • 應用: Verify Package
  • cross-certify
  • 應用: Thunderbird - Enigmail

 

有關檔案

  • secret keys:                 secring.gpg
  • public keys:                  pubring.gpg
  • trust database::           trustdb.gpg
  • GnuPG configuration:    gpg.conf

一般選項

  •  -v, --verbose              verbose
  •  -n, --dry-run              do not make any changes

常用選項

  • -k, --list-keys
  • -K, --list-secret-keys
  • --gen-key
  • --fingerprint
  • --delete-secret-keys
  • --delete-keys
  • --import
  • --export
  • --export-secret-keys

 

使用過程

 

# 建立 Secret Key:

gpg --gen-key

"Name (Comment) <E-Mail>"

# 過程:

Please select what kind of key you want:
   (1) RSA and RSA (default)
   (2) DSA and Elgamal
   (3) DSA (sign only)
   (4) RSA (sign only)
Your selection?                                    <-- 按 Enter
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048)                   <-- 按 Enter
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)                               <-- 按 Enter
Key does not expire at all
Is this correct? (y/N) y                            <-- 按 y

GnuPG needs to construct a user ID to identify your key.
   
   
Real name: ???
Email address: ???@gmail.com
Comment:
You selected this USER-ID:
    "??? <???@gmail.com>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o   <-- 按 o
You need a Passphrase to protect your secret key.

 

# key 在 M$ 的位置:

C:\Users\admin\AppData\Roaming\gnupg

 

# 清空它後, 可以用 -k 及 -K 建立它

c:\e-mail_key>gpg -k

gpg: keyring `C:/Users/admin/AppData/Roaming/gnupg/pubring.gpg' created
gpg: C:/Users/admin/AppData/Roaming/gnupg/trustdb.gpg: trustdb created

c:\e-mail_key>gpg -K

gpg: keyring `C:/Users/admin/AppData/Roaming/gnupg/secring.gpg' created

 

Get Local KeyID

 

查看有什麼 Public Key:

gpg --list-keys [e-mail]        <---      gpg -k

gpg --list-keys [public_key]

----------------------------------------------
pub   2048R/7CE3826E 2011-12-01 [expires: 2016-11-29]
uid                  ??? <???@yourdomain>
sub   2048R/927D9534 2011-12-01 [expires: 2016-11-29]

pub   2048R/BB840272 2012-10-22
uid                  ??? <???@gmail.com>
sub   2048R/0E142A39 2012-10-22

gpg --list-sigs

與 --list-keys 差不多, 多了 signatures

"L"       for a local or non-exportable signature

"1-9"   signature levels

gpg --check-sigs

/root/.gnupg/pubring.kbx
------------------------
pub   rsa4096 2014-01-11 [SC]
      E7FB0CAEC8173D669066514CBAEFF88C22F6E216
uid           [ unknown] LXC pre-built images <lxc-devel@lists.linuxcontainers.org>
sig!3        BAEFF88C22F6E216 2014-01-11  LXC pre-built images <lxc-devel@lists.linuxcontainers.org>

gpg: 1 good signature

與 --list-sigs 差不多, 多了 verify

  • "!"   successfully verified
  • "-"   bad signature
  • "%" error occurred

查看所有 private key:

gpg --list-secret-keys         <---     gpg -K

C:/Users/admin/AppData/Roaming/gnupg/secring.gpg
----------------------------------------------
sec   2048R/BB840272 2012-10-22
uid                  Tim.Lau <???@gmail.com>
ssb   2048R/0E142A39 2012-10-22

fingerprint

gpg --fingerprint

----------------------------------------------
pub   2048R/7CE3826E 2011-12-01 [expires: 2016-11-29]
      Key fingerprint = 0BF0 A6AD CCAA FE7A 0225  11A3 6833 F82B 7CE3 826E
uid                  ??? <???@yourdomain>
sub   2048R/927D9534 2011-12-01 [expires: 2016-11-29]

pub   2048R/BB840272 2012-10-22
      Key fingerprint = CE72 DA62 F5C5 F1CF ADCA  18BB 2F81 4FEE BB84 0272
uid                  ??? <???@gmail.com>
sub   2048R/0E142A39 2012-10-22

 

Delete Key

 

# Private:

gpg --delete-secret-keys 7CE3826E

Delete this key from the keyring? (y/N) y
This is a secret key! - really delete? (y/N) y

# Public:

gpg --delete-keys 7CE3826E

Delete this key from the keyring? (y/N) y

# 一次過 Delete Pri & Pub key:

--delete-secret-and-public-key name

 

 

Export / Import Key

 

ASCII格式:

gpg -a --export BB840272                    <---    --armor

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v2.0.17 (MingW32)
.....................................................
-----END PGP PUBLIC KEY BLOCK-----

二進制格式:

gpg -o key.bin --export BB840272         <---   --output FILE

Export Private Key:

gpg -a -o key.txt --export-secret-keys 6F4131E7

import keyrings(public key):

gpg --import <keyring_files>

i.e.

gpg --verify burp-2.2.18.tar.bz2.asc

gpg: assuming signed data in 'burp-2.2.18.tar.bz2'
gpg: Signature made Sun 24 Feb 2019 12:51:39 PM HKT
gpg:                using RSA key 28386B441AB24FD49766FBF73A68D2214C21357C
gpg: Can't check signature: No public key

wget https://burp.grke.org/downloads/grke.gpg

gpg --import grke.gpg

gpg: starting migration from earlier GnuPG versions
gpg: porting secret keys from '/root/.gnupg/secring.gpg' to gpg-agent
gpg: migration succeeded
gpg: key 3A68D2214C21357C: public key "Graham Keeling <grke@grke.net>" imported
gpg: Total number processed: 1
gpg:               imported: 1

gpg --verify burp-2.2.18.tar.bz2.asc

gpg: assuming signed data in 'burp-2.2.18.tar.bz2'
gpg: Signature made Sun 24 Feb 2019 12:51:39 PM HKT
gpg:                using RSA key 28386B441AB24FD49766FBF73A68D2214C21357C
gpg: Good signature from "Graham Keeling <grke@grke.net>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 2838 6B44 1AB2 4FD4 9766  FBF7 3A68 D221 4C21 357C

 

廢棄證書

 

gpg --output revocation-certificate.asc --gen-revoke <KeyID>

報廢過程:

載入 revocation-certificate 到本地的 keyring

gpg --import revocation-certificate.asc

上載到 KeyServer

gpg --send-keys <ID>

Example:

gpg --output revocation-certificate.txt --gen-revoke 6F4131E7

sec  2048R/6F4131E7 2012-10-22 ??? <???@gmail.com>

Create a revocation certificate for this key? (y/N) y
Please select the reason for the revocation:
  0 = No reason specified
  1 = Key has been compromised
  2 = Key is superseded
  3 = Key is no longer used
  Q = Cancel
(Probably you want to select 1 here)
Your decision? 1
Enter an optional description; end it with an empty line:
>
Reason for revocation: Key has been compromised
(No description given)
Is this okay? (y/N) y
NOTE: This key is not protected!
ASCII armored output forced.
Revocation certificate created.

 

上載 Public Key 到 KeyServer

 

[1] 查看本機有的 Public Key:

gpg -k

/root/.gnupg/pubring.kbx
------------------------
pub   rsa4096 2014-01-11 [SC]
      E7FB0CAEC8173D669066514CBAEFF88C22F6E216
uid           [ unknown] LXC pre-built images <lxc-devel@lists.linuxcontainers.org>

[2] 上載它到 Server:

gpg --send-keys 0xKeyID

                        OR

gpg --keyserver hkp://subkeys.pgp.net --send-keys <KeyID>

[3] 設定預設 KeyServer

預設的穩定 keyserver 寫在 $HOME/.gnupg/gpg.conf

...........................
keyserver hkp://keys.gnupg.net
...........................

 * 只能指定一個 keyserver

Centos6 Default:

-rw-------. 1 root root 7856 Aug 13 15:33 gpg.conf

gpg.conf

require-cross-certification
keyserver hkp://keys.gnupg.net

 

在 Server 上找別人的 Key

 

用 E-Mail 在 Server 上找某人的 Key:

gpg --keyserver hkp://subkeys.pgp.net --search-keys '???@gmail.com'

找不到 key:

gpg: searching for "'???@gmail.com'" from hkp server subkeys.pgp.net
gpg: key "'???@gmail.com'" not found on keyserver

當 key 存在:

gpg: searching for "'???@gmail.com'" from hkp server subkeys.pgp.net
(1)     Tim.Lau <???@gmail.com>
          2048 bit RSA key 6F4131E7, created: 2012-10-22
Keys 1-1 of 1 for "'???@gmail.com'".  Enter number(s), N)ext, or Q)uit > 1
gpg: requesting key 6F4131E7 from hkp server subkeys.pgp.net
gpg: key 6F4131E7: "Tim.Lau <???@gmail.com>" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1

 

從 KeyServer 下載別人的 Key 回來:

gpg --recv-keys IDs

 

從 Server 下載 Local 有的 Key 回來:

gpg --refresh-keys

 

把自己的 Public Key 比別人

 

建立有你 fingerprint,  type,  size 的紙條

gpg-key2ps

確認對方的公匙

gpg --fingerprint < UID >

導入對方的公匙

gpg --import < filename >

 

簽名與鑑定

 

簽名:

gpg [-o filename.gpg] -s filename             # (簽名+內容)

gpg -b filename                                       # (簽名, 內容)

生成的簽名檔案有兩類及兩種保存方式

簽名, 內容 (-b)

  • .sig (default)
  • .asc (-b -a)

簽名+內容 (default)

  • asc - ASCII file (-a)
  • gpg - binary (default)

鑑定:

gpg --verify filename.sig [filename]

i.e.

gpg --verify dovecot-2.1.17.tar.gz.sig

The output should say "Good signature":

gpg: Signature made Thu 27 Jun 2013 03:05:07 AM HKT using DSA key ID 40558AC9
gpg: Good signature from "Timo Sirainen <tss@iki.fi>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: E643 F0BD FDCD 04D9 FFCB  6279 C948 5251 4055 8AC9
  • 那 WARNING 的意思是 "none of those people have also signed your key."

 

--sign | -s

--armor | -a

--output | -o

--recipient | -r

--detach-sign | -b

 

檔案的加密與解密:

 

加密:

gpg -r < 對方的E-Mail > -e <file>

解密:

gpg -d < file >

 

-e, --encrypt

-d, --decrypt

-r, --recipient

 

web of trust

 

簽名的目的是證明您完全信任這個證書的合法性

# revsig      revoke signatures on the selected user IDs

gpg --sign-key < UID >                        // Signs a public key with your secret key.

gpg --check-sigs < UID >

Your -T-> Alice -T-> Bob

If your friend Bob already has a trusted key from Alice, then Bob can certify the integrity of that key for you.

He can do this by giving you a signed copy of Alice's key.

If you trust Bob to sign public keys only when he is absolutely confident of their authenticity,

you can then gain trust in Alice's key even if you can't obtain it from her in person.

 

如果別人已把金鑰上傳到 key server, 您可以從 key server 下載您的新金鑰

gpg --keyserver wwwkeys.uk.pgp.net --recv-keys your_keyid

"local" signatures (--lsign-key)

A local signature is one that cannot be exported together with the public key to which it applies.

This prevents your signature from being propagated if you send a copy of the signed key to anyone else.

tsign

sign selected user IDs with a trust signature

nrsign

sign selected user IDs with a non-revocable signature

應用: 在 Mutt 中使用 GnuPG

 

在 ~/.muttrc 中加入下列的內容，則如果你在 index 選單中輸入 `S' 的話，將會自動啟動一個低速的 GnuPG。

     macro index S ":toggle pgp_verify_sig\n"
     set pgp_verify_sig=no

在 Vim 中使用 GnuPG

將 examples subdirectory 中的 _vimrc 文件的內容加到 ~/.vimrc 就可以自然的執行 GnuPG.

 

Trust code:

  • -         No ownertrust assigned / not yet calculated.
  • e         計算信任度失敗。
  • q        計算所需的資訊不足。
  • n        永不信任這把 key。
  • m       Marginally trusted.
  • f         完全信任 (Fully trusted)。
  • u        極度信任 (Ultimately trusted)。

 

PGP public key server

 

  • wwwkeys.pgp.net
  • wwwkeys.uk.pgp.net
  • subkeys.pgp.net

 

Gpg4Win

 

Window 上的 opengpg

Download: https://www.gpg4win.de/download.html

Package

  • gpg4win-light-2.3.4.exe @20191008
  • gpg4win-3.1.10.exe @20191008

Remark

Gpg4Win <= 2.1.0 passphrase does not work in a non-English "Language"

light & vanilla

gpg4win-vanilla and gpg4win-light have been left on the now outdated and not maintained 2.0 gpg branch.

These packages have not been updated for more than a year and are potentially putting users of these at risk.

 

Verify Package

 

.asc file

-----BEGIN PGP SIGNATURE-----
...
-----END PGP SIGNATURE-----

# Verify Package by ".asc" file

# .tar.gz 與 .tar.gz.asc 不在用一目錄時

gpg --verify rsync-3.1.2.tar.gz.asc rsync-3.1.2.tar.gz

gpg: Signature made Tue 22 Dec 2015 04:25:56 AM HKT using DSA key ID 4B96A8C5
gpg: Can't check signature: No public key

Remark1: 在同一目錄時

gpg --verify rsync-3.1.2.tar.gz.asc

Remark 2:

fingerprint

# Get Public Key & Verify

gpg --recv-keys 4B96A8C5

gpg: requesting key 4B96A8C5 from hkp server keys.gnupg.net
gpg: /root/.gnupg/trustdb.gpg: trustdb created
gpg: key 4B96A8C5: public key "Wayne Davison <wayned@users.sourceforge.net>" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1

gpg --verify rsync-3.1.2.tar.gz.asc

gpg: Signature made Tue 22 Dec 2015 04:25:56 AM HKT using DSA key ID 4B96A8C5
gpg: Good signature from "Wayne Davison <wayned@users.sourceforge.net>"
gpg:                 aka "Wayne Davison <wayned@samba.org>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 0048 C8B0 26D4 C96F 0E58  9C2F 6C85 9FB1 4B96 A8C5

Warning

gpg: WARNING: This key is not certified with a trusted signature!

the key in your keyring & the signatures are valid, but either you have not marked the keys as trusted

 => no proof it belongs to whom it pretends to

 => Compare the fingerprints with those shown on business cards / homepage

Trust level (當 fingerprint 對完 homeage 正確時)

Edit trust level of keys by running "gpg --edit-key", and then using the trust command.

gpg --edit-key <fingerprint>

gpg> trust

...
  1 = I don't know or won't say
  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? 3

gpg> quit

Trust in a key's owner(1~5)

A key's trust level is something that you alone assign to the key, and it is considered private information.

It is not packaged with the key when it is exported; it is even stored separately from your keyrings in a separate database.

There are 4 trust levels:

unknown

Nothing is known about the owner's judgement in key signing.

(Keys on your public keyring that you do not own initially have this trust level.)

none

The owner is known to improperly sign other keys.

marginal

The owner understands the implications of key signing and properly validates keys before signing them.

full

The owner has an excellent understanding of key signing, and his signature on a key would be as good as your own.

Find out when it expires

# -k, --list-keys

gpg -k 4B96A8C5

pub   1024D/4B96A8C5 2003-12-19
uid                  Wayne Davison <wayned@users.sourceforge.net>
uid                  Wayne Davison <wayned@samba.org>
sub   1024g/29C67D63 2003-12-19

Update Keys

gpg --refresh-keys

 

Key usage Flag

 

S -> for signing

E -> for encrypting

C -> Certification (Sign a key)

A -> Authentication (logging in)

D -> to indicate a disabled key

Defaults to no flag

 

Subkey Cross-certify

 

"Verifying a signature from someone" 出現 => "signing subkey is not cross-certified"

Reason

The signature that you verified has not been tampered with,
but might not have been issued by the person who sent it to you.

An OpenPGP key is made up of several keys:

  • Primary key
  • Subkeys
PriKey --> SubKey --> Package --> Verify
             /\
             ||
      Attacker: PriKey

Primary key

which is used to digitally sign things, and optionally, subkeys that can be used to sign or encrypt things.

To prove that the subkeys "belong" to the key and were not inserted by an attacker,

they are digitally signed by the primary key.

Most users use their primary key for signing, and a subkey for encryption,

and this is the default key style in both GnuPG and PGP.

Signing subkeys weakness

There is a subtle weakness in the OpenPGP design for signing subkeys.

Recall that subkeys are signed by the primary key to show they belong to the primary key.

However, the signing subkey does not sign the primary to show that it is owned by the primary.

This allows an attacker to take a signing subkey and attach it to their own key.

Subkey cross-certification

sometimes called "back signing". involves the subkey issuing a signature on the primary key,

just like the primary key signature on the subkey.

Fix

gpg --edit-key (yourkey)

then enter "cross-certify"

 

應用: Thunderbird - Enigmail

 

http://www.enigmail.net/home/index.php

收件設定: Decryt & Verify

 

寄件設定:

信任對方的 Key:

<MIME Header>

PGP/MIME is a standard defined in RFC 3156 (inline-PGP standard)

當別人的 E-Mail Client 無 GPG 功能時, 那"簽名"就會以附件形式存在: signature.asc

內容則是 html 形式存在

已知支援的 Client: 2014-02-20

(Apple Mail, Becky, Evolution, KMail, Mulberry, Sylpheed and The Bat!.)

不用 MIME 的 Mail:

當格式是 HTML 時, 就會有 Warning

Mail 的 Source 內容:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
 
test
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.17 (MingW32)
Comment: Using GnuPG with Mozilla - http://www.enigmail.net/
 
iQEcBAEBAgAGBQJQjSNoAAoJEMNEx0ZvQTHnoYcIAL82miLiUo2n/Yj+rflVtMLd
................................................................
-----END PGP SIGNATURE-----

用 MIME 的 Mail Source:

Content-Type: multipart/signed; micalg=pgp-sha1;
 protocol="application/pgp-signature";
 boundary="------------enigC43BDF83D84A140632D2F633"

This is an OpenPGP/MIME signed message (RFC 2440 and 3156)
--------------enigC43BDF83D84A140632D2F633
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

testing


--------------enigC43BDF83D84A140632D2F633
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.17 (MingW32)
Comment: Using GnuPG with Mozilla - http://www.enigmail.net/

iQEcBAEBAgAGBQJQjRzyAAoJEMNEx0ZvQTHnRQIIAIMzAGC1+50h+mVdrdnWCrhB
..............................................................
-----END PGP SIGNATURE-----

--------------enigC43BDF83D84A140632D2F633--

指明自己是用那個 keyserver

Advanced -> Send 'OpenPGP' Header -> Send URL for key retrieval

# OpenPGP: url=pool.sks-keyservers.net

 

 

 

 

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