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Use the long GPG key ID instead of the short one

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Update the text to prefer the long (16-char) GPG key ID instead of
the unsafe short key ID.  The Fedora Accounts "SSH & GPG Keys"
settings page, for example, does not allow use of the short ID, so
it would be good to explain how to determine the long one.
This commit is contained in:
Brian Rosmaita 2023-06-06 01:04:39 +00:00
parent addd134a90
commit 22ce320348
1 changed files with 27 additions and 3 deletions
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30
modules/ROOT/pages/_partials/proc_creating-gpg-keys-cli.adoc
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@ -98,9 +98,33 @@ To display the fingerprint at any time, use this command, substituting your emai
gpg --fingerprint johndoe@example.com
----
Your _GPG key ID_ consists of 8 hex digits identifying the public key.
In the example above, the GPG key ID is `36BF353A`.
In most cases, if you are asked for the key ID, you should prepend "0x" to the key ID, as in `0x36BF353A`.
Your key fingerprint is actually a 160 bit SHA-1 hash of the key, represented as a 40 character string of hexadecimal digits.
Though shorter than the public key itself, it's still a bit unwieldy, so people tend to use a shorter _GPG key ID_ to refer to a key when, for example, looking up a key in a keyserver.
The GPG key ID is a small number of hex digits drawn from the characters representing the lower-order bits of the fingerprint.
The "short" GPG key ID consists of the final 8 characters of the hexadecimal fingerprint, that is, the last 32 bits of the fingerprint.
Short keys are unsafe and no longer recommended because it's possible to create collisions so that an attacker's forged key has the same short ID as your key.
Thus if you give someone the short GPG key ID of your key, they may retrieve the attacker's key from a keyserver instead.
For this reason, it's preferred to use the "long" GPG key ID, which consists of the final 16 characters of your key's hexadecimal fingerprint.
This represents the 64 lower-order bits of your fingerprint, which is sufficient to be collision-resistant.
The `gpg` program makes it easy for you to find your key's long GPG key ID:
----
gpg --list-keys --fingerprint --key-id-format 0xlong johndoe@example.com
----
The `0xlong` format prepends "0x" to the key ID to make it clear that this is a series of hexadecimal digits; it is considered good practice to do this.
The output from the above command looks like this:
---
pub rsa3072/0x26FBCC7836BF353A 2021-02-09 [SC] [expires: 2022-02-09]
Key fingerprint = 3782 CBB6 0147 010B 3305 23DD 26FB CC78 36BF 353A
uid John Doe (Fedora Docs) <johndoe@example.com>
sub rsa3072/0xF834D62672E88A6F 2021-02-09 [E] [expires: 2022-02-09]
---
The first line (beginning with "pub") tells you what kind the key is (that is, 3072 bit RSA) and what the long key ID is (that is, `0x26FBCC7836BF353A`).
You can see that this corresponds to the last 16 characters of the Key fingerprint in the output.
Now see <<backup-gpg-keys-cli>>.
Make sure to back up your revocation keys for all active keys as this allows to revoke keys in the event of lost passphrase of key compromise.