☰

为什么 GPG 不能使用所有子密钥解密？

tag-icon • tag-icon encryption gnupg
为什么 GPG 不能使用所有子密钥解密？

我有多个用于签名和加密的子密钥。这是我的公钥和私钥列表。

jeremy@localhost ~ 
$ gpg -k
/home/jeremy/.gnupg/pubring.gpg
-------------------------------
pub   4096R/35E40FA7 2015-04-14
uid                  keybase.io/jeremytwfortune <[email protected]>
uid                  Jeremy Fortune <[email protected]>
uid                  Jeremy Fortune <[email protected]>
sub   2048R/73671EAD 2015-04-14 [expires: 2023-04-12]
sub   2048R/0690427C 2015-04-14 [expires: 2023-04-12]
sub   4096R/AEE9FB5F 2015-12-06 [expires: 2025-12-03]
sub   4096R/757D1A1D 2015-12-06 [expires: 2025-12-03]
sub   2112R/9B5BAC36 2015-12-06 [expires: 2025-12-03]
sub   4096R/5A8F548A 2015-12-06 [expires: 2025-12-03]


jeremy@localhost ~ 
$ gpg -K
/home/jeremy/.gnupg/secring.gpg
-------------------------------
sec   4096R/35E40FA7 2015-04-14
uid                  keybase.io/jeremytwfortune <[email protected]>
ssb   2048R/73671EAD 2015-04-14
ssb   2048R/0690427C 2015-04-14

当我给自己加密消息时，会使用最新的加密密钥 (9b5bac36)。这似乎没问题，因为它是一个子密钥，但在解密时，gpg 仍然只寻找该私钥。它甚至不会尝试使用 0690427c。

jeremy@localhost ~ 
$ echo -e "\nAn encrypted message." | gpg -vver 35e40fa7 | gpg -vvd
gpg: using subkey 9B5BAC36 instead of primary key 35E40FA7
gpg: using PGP trust model
gpg: key 35E40FA7: accepted as trusted key 
gpg: checking the trustdb
gpg: 1 keys cached (11 signatures)
gpg: 1 keys processed (0 validity counts cleared)
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
gpg: This key belongs to us
gpg: reading from `[stdin]'
gpg: writing to stdout
gpg: RSA/AES256 encrypted for: "9B5BAC36 keybase.io/jeremytwfortune <[email protected]>"
:pubkey enc packet: version 3, algo 1, keyid 743409AA9B5BAC36
        data: [2111 bits]
gpg: public key is 9B5BAC36
:encrypted data packet:
        length: 76
        mdc_method: 2
gpg: using subkey 9B5BAC36 instead of primary key 35E40FA7
gpg: encrypted with 2112-bit RSA key, ID 9B5BAC36, created 2015-12-06
      "keybase.io/jeremytwfortune <[email protected]>"
gpg: decryption failed: secret key not available

当我撤销较新的加密密钥时，一切都按预期进行。

jeremy@localhost ~
$ gpg -k
/home/jeremy/.gnupg/pubring.gpg
-------------------------------
pub   4096R/35E40FA7 2015-04-14
uid                  keybase.io/jeremytwfortune <[email protected]>
uid                  Jeremy Fortune <[email protected]>
uid                  Jeremy Fortune <[email protected]>
sub   2048R/73671EAD 2015-04-14 [expires: 2023-04-12]
sub   2048R/0690427C 2015-04-14 [expires: 2023-04-12]
sub   4096R/AEE9FB5F 2015-12-06 [expires: 2025-12-03]
sub   4096R/5A8F548A 2015-12-06 [expires: 2025-12-03]

jeremy@localhost ~
$ echo -e "\nAn encrypted message." | gpg -vver 35e40fa7 | gpg -vvd
gpg: using subkey 0690427C instead of primary key 35E40FA7
gpg: using PGP trust model
gpg: key 35E40FA7: accepted as trusted key
gpg: This key belongs to us
gpg: reading from `[stdin]'
gpg: writing to stdout
gpg: RSA/AES256 encrypted for: "0690427C keybase.io/jeremytwfortune <[email protected]>"
:pubkey enc packet: version 3, algo 1, keyid 60A3F13E0690427C
        data: [2045 bits]
gpg: public key is 0690427C
gpg: no secret subkey for public subkey AEE9FB5F - ignoring
gpg: no secret subkey for public subkey 5A8F548A - ignoring
gpg: using subkey 0690427C instead of primary key 35E40FA7

You need a passphrase to unlock the secret key for
user: "keybase.io/jeremytwfortune <[email protected]>"
gpg: using subkey 0690427C instead of primary key 35E40FA7
2048-bit RSA key, ID 0690427C, created 2015-04-14 (main key ID 35E40FA7)
gpg: gpg-agent is not available in this session
gpg: public key encrypted data: good DEK
:encrypted data packet:
        length: 76
        mdc_method: 2
gpg: encrypted with 2048-bit RSA key, ID 0690427C, created 2015-04-14
      "keybase.io/jeremytwfortune <[email protected]>"
gpg: AES256 encrypted data
:compressed packet: algo=1
:literal data packet:
        mode b (62), created 1458172973, name="",
        raw data: 23 bytes
gpg: original file name=''

An encrypted message.
gpg: decryption okay

但当然，这是因为它现在使用 0690427c 加密。我真的只能有一个加密子密钥吗？如果不行，我是否必须在每台机器上保留所有秘密子密钥？

答案1

OpenPGP（包括 GnuPG）的实现将默认选择最新的有效加密（子）密钥并使用它进行加密。在 OpenPGP 中，无法定义给定子密钥以某种方式绑定到给定计算机或用户 ID，也无法强制对所有有效加密密钥执行加密。

人们可以很好地手动使用所选的密钥 ID 作为接收者，选择用于 GnuPG 加密的密钥，但后跟!。例如，假设有一个较旧的加密子密钥DEADBEEF，并且您想要覆盖使用另一个较新的加密子密钥的默认设置：

gpg --recipient DEADBEEF! --encrypt

如果!省略，GnuPG 会将密钥 ID 解析为主密钥，并再次选择最新匹配的子密钥。使用相同的方法，您可以强制使用主密钥（如果它具有加密功能集）。

如果要在不同的计算机上使用不同的密钥进行加密，则必须使用不同的主密钥。这是 OpenPGP 的主要缺点之一。

相关内容