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| -rw-r--r-- | Documentation/config/gpg.txt | 85 |
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diff --git a/Documentation/config/gpg.txt b/Documentation/config/gpg.txt new file mode 100644 index 0000000..5cf32b1 --- /dev/null +++ b/Documentation/config/gpg.txt @@ -0,0 +1,85 @@ +gpg.program:: + Use this custom program instead of "`gpg`" found on `$PATH` when + making or verifying a PGP signature. The program must support the + same command-line interface as GPG, namely, to verify a detached + signature, "`gpg --verify $signature - <$file`" is run, and the + program is expected to signal a good signature by exiting with + code 0. To generate an ASCII-armored detached signature, the + standard input of "`gpg -bsau $key`" is fed with the contents to be + signed, and the program is expected to send the result to its + standard output. + +gpg.format:: + Specifies which key format to use when signing with `--gpg-sign`. + Default is "openpgp". Other possible values are "x509", "ssh". ++ +See linkgit:gitformat-signature[5] for the signature format, which differs +based on the selected `gpg.format`. + +gpg.<format>.program:: + Use this to customize the program used for the signing format you + chose. (see `gpg.program` and `gpg.format`) `gpg.program` can still + be used as a legacy synonym for `gpg.openpgp.program`. The default + value for `gpg.x509.program` is "gpgsm" and `gpg.ssh.program` is "ssh-keygen". + +gpg.minTrustLevel:: + Specifies a minimum trust level for signature verification. If + this option is unset, then signature verification for merge + operations requires a key with at least `marginal` trust. Other + operations that perform signature verification require a key + with at least `undefined` trust. Setting this option overrides + the required trust-level for all operations. Supported values, + in increasing order of significance: ++ +* `undefined` +* `never` +* `marginal` +* `fully` +* `ultimate` + +gpg.ssh.defaultKeyCommand:: + This command will be run when user.signingkey is not set and a ssh + signature is requested. On successful exit a valid ssh public key + prefixed with `key::` is expected in the first line of its output. + This allows for a script doing a dynamic lookup of the correct public + key when it is impractical to statically configure `user.signingKey`. + For example when keys or SSH Certificates are rotated frequently or + selection of the right key depends on external factors unknown to git. + +gpg.ssh.allowedSignersFile:: + A file containing ssh public keys which you are willing to trust. + The file consists of one or more lines of principals followed by an ssh + public key. + e.g.: `user1@example.com,user2@example.com ssh-rsa AAAAX1...` + See ssh-keygen(1) "ALLOWED SIGNERS" for details. + The principal is only used to identify the key and is available when + verifying a signature. ++ +SSH has no concept of trust levels like gpg does. To be able to differentiate +between valid signatures and trusted signatures the trust level of a signature +verification is set to `fully` when the public key is present in the allowedSignersFile. +Otherwise the trust level is `undefined` and git verify-commit/tag will fail. ++ +This file can be set to a location outside of the repository and every developer +maintains their own trust store. A central repository server could generate this +file automatically from ssh keys with push access to verify the code against. +In a corporate setting this file is probably generated at a global location +from automation that already handles developer ssh keys. ++ +A repository that only allows signed commits can store the file +in the repository itself using a path relative to the top-level of the working tree. +This way only committers with an already valid key can add or change keys in the keyring. ++ +Since OpensSSH 8.8 this file allows specifying a key lifetime using valid-after & +valid-before options. Git will mark signatures as valid if the signing key was +valid at the time of the signature's creation. This allows users to change a +signing key without invalidating all previously made signatures. ++ +Using a SSH CA key with the cert-authority option +(see ssh-keygen(1) "CERTIFICATES") is also valid. + +gpg.ssh.revocationFile:: + Either a SSH KRL or a list of revoked public keys (without the principal prefix). + See ssh-keygen(1) for details. + If a public key is found in this file then it will always be treated + as having trust level "never" and signatures will show as invalid. |