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Use the long GPG key ID instead of the short one
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.
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@ -98,9 +98,33 @@ To display the fingerprint at any time, use this command, substituting your emai
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gpg --fingerprint johndoe@example.com
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gpg --fingerprint johndoe@example.com
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----
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----
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Your _GPG key ID_ consists of 8 hex digits identifying the public key.
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Your key fingerprint is actually a 160 bit SHA-1 hash of the key, represented as a 40 character string of hexadecimal digits.
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In the example above, the GPG key ID is `36BF353A`.
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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.
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In most cases, if you are asked for the key ID, you should prepend "0x" to the key ID, as in `0x36BF353A`.
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The GPG key ID is a small number of hex digits drawn from the characters representing the lower-order bits of the fingerprint.
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The "short" GPG key ID consists of the final 8 characters of the hexadecimal fingerprint, that is, the last 32 bits of the fingerprint.
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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.
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Thus if you give someone the short GPG key ID of your key, they may retrieve the attacker's key from a keyserver instead.
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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.
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This represents the 64 lower-order bits of your fingerprint, which is sufficient to be collision-resistant.
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The `gpg` program makes it easy for you to find your key's long GPG key ID:
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----
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gpg --list-keys --fingerprint --key-id-format 0xlong johndoe@example.com
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----
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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.
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The output from the above command looks like this:
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---
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pub rsa3072/0x26FBCC7836BF353A 2021-02-09 [SC] [expires: 2022-02-09]
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Key fingerprint = 3782 CBB6 0147 010B 3305 23DD 26FB CC78 36BF 353A
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uid John Doe (Fedora Docs) <johndoe@example.com>
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sub rsa3072/0xF834D62672E88A6F 2021-02-09 [E] [expires: 2022-02-09]
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---
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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`).
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You can see that this corresponds to the last 16 characters of the Key fingerprint in the output.
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Now see <<backup-gpg-keys-cli>>.
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Now see <<backup-gpg-keys-cli>>.
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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.
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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.
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