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2022-01-26Documentation/config/pgp.txt: add missing apostropheLibravatar Greg Hurrell1-1/+1
Add an apostrophe to "signatures" to indicate the possessive relationship in "the signature's creation". Signed-off-by: Greg Hurrell <greg@hurrell.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-26Documentation/config/pgp.txt: replace stray <TAB> character with <SPC>Libravatar Greg Hurrell1-1/+1
Specifically, replace the tab between "the" and "first" with a space. Signed-off-by: Greg Hurrell <greg@hurrell.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-05Merge branch 'gh/gpg-doc-markup-fix'Libravatar Junio C Hamano1-1/+1
Doc markup fix. * gh/gpg-doc-markup-fix: docs: add missing colon to Documentation/config/gpg.txt
2022-01-05Merge branch 'jk/ssh-signing-doc-markup-fix'Libravatar Junio C Hamano1-1/+1
Docfix. * jk/ssh-signing-doc-markup-fix: doc/config: mark ssh allowedSigners example as literal
2021-12-17docs: add missing colon to Documentation/config/gpg.txtLibravatar Greg Hurrell1-1/+1
Add missing colon to ensure correct rendering of definition list item. Without the proper number of colons, it renders as just another top-level paragraph rather than a list item. Signed-off-by: Greg Hurrell <greg@hurrell.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-15doc/config: mark ssh allowedSigners example as literalLibravatar Jeff King1-1/+1
The discussion for gpg.ssh.allowedSignersFile shows an example string that contains "user1@example.com,user2@example.com". Asciidoc thinks these are real email addresses and generates "mailto" footnotes for them. This makes the rendered content more confusing, as it has extra "[1]" markers: The file consists of one or more lines of principals followed by an ssh public key. e.g.: user1@example.com[1],user2@example.com[2] ssh-rsa AAAAX1... See ssh-keygen(1) "ALLOWED SIGNERS" for details. and also generates pointless notes at the end of the page: NOTES 1. user1@example.com mailto:user1@example.com 2. user2@example.com mailto:user2@example.com We can fix this by putting the example into a backtick literal block. That inhibits the mailto generation, and as a bonus typesets the example text in a way that sets it off from the regular prose (a tt font for html, or bold in the roff manpage). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-09ssh signing: make verify-commit consider key lifetimeLibravatar Fabian Stelzer1-0/+5
If valid-before/after dates are configured for this signatures key in the allowedSigners file then the verification should check if the key was valid at the time the commit was made. This allows for graceful key rollover and revoking keys without invalidating all previous commits. This feature needs openssh > 8.8. Older ssh-keygen versions will simply ignore this flag and use the current time. Strictly speaking this feature is available in 8.7, but since 8.7 has a bug that makes it unusable in another needed call we require 8.8. Timestamp information is present on most invocations of check_signature. However signer ident is not. We will need the signer email / name to be able to implement "Trust on first use" functionality later. Since the payload contains all necessary information we can parse it from there. The caller only needs to provide us some info about the payload by setting payload_type in the signature_check struct. - Add payload_type field & enum and payload_timestamp to struct signature_check - Populate the timestamp when not already set if we know about the payload type - Pass -Overify-time={payload_timestamp} in the users timezone to all ssh-keygen verification calls - Set the payload type when verifying commits - Add tests for expired, not yet valid and keys having a commit date outside of key validity as well as within Signed-off-by: Fabian Stelzer <fs@gigacodes.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-13ssh signing: clarify trustlevel usage in docsLibravatar Fabian Stelzer1-3/+1
facca53ac added verification for ssh signatures but incorrectly described the usage of gpg.minTrustLevel. While the verifications trustlevel is stil set to fully or undefined depending on if the key is known or not it has no effect on the verification result. Unknown keys will always fail verification. This commit updates the docs to match this behaviour. Signed-off-by: Fabian Stelzer <fs@gigacodes.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-10ssh signing: verify signatures using ssh-keygenLibravatar Fabian Stelzer1-0/+35
To verify a ssh signature we first call ssh-keygen -Y find-principal to look up the signing principal by their public key from the allowedSignersFile. If the key is found then we do a verify. Otherwise we only validate the signature but can not verify the signers identity. Verification uses the gpg.ssh.allowedSignersFile (see ssh-keygen(1) "ALLOWED SIGNERS") which contains valid public keys and a principal (usually user@domain). Depending on the environment this file can be managed by the individual developer or for example generated by the central repository server from known ssh keys with push access. This file is usually stored outside the repository, but if the repository only allows signed commits/pushes, the user might choose to store it in the repository. To revoke a key put the public key without the principal prefix into gpg.ssh.revocationKeyring or generate a KRL (see ssh-keygen(1) "KEY REVOCATION LISTS"). The same considerations about who to trust for verification as with the allowedSignersFile apply. Using SSH CA Keys with these files is also possible. Add "cert-authority" as key option between the principal and the key to mark it as a CA and all keys signed by it as valid for this CA. See "CERTIFICATES" in ssh-keygen(1). Signed-off-by: Fabian Stelzer <fs@gigacodes.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-10ssh signing: retrieve a default key from ssh-agentLibravatar Fabian Stelzer1-0/+6
If user.signingkey is not set and a ssh signature is requested we call gpg.ssh.defaultKeyCommand (typically "ssh-add -L") and use the first key we get Signed-off-by: Fabian Stelzer <fs@gigacodes.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-10ssh signing: add ssh key format and signing codeLibravatar Fabian Stelzer1-2/+2
Implements the actual sign_buffer_ssh operation and move some shared cleanup code into a strbuf function Set gpg.format = ssh and user.signingkey to either a ssh public key string (like from an authorized_keys file), or a ssh key file. If the key file or the config value itself contains only a public key then the private key needs to be available via ssh-agent. gpg.ssh.program can be set to an alternative location of ssh-keygen. A somewhat recent openssh version (8.2p1+) of ssh-keygen is needed for this feature. Since only ssh-keygen is needed it can this way be installed seperately without upgrading your system openssh packages. Signed-off-by: Fabian Stelzer <fs@gigacodes.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-01-15gpg-interface: add minTrustLevel as a configuration optionLibravatar Hans Jerry Illikainen1-0/+15
Previously, signature verification for merge and pull operations checked if the key had a trust-level of either TRUST_NEVER or TRUST_UNDEFINED in verify_merge_signature(). If that was the case, the process die()d. The other code paths that did signature verification relied entirely on the return code from check_commit_signature(). And signatures made with a good key, irregardless of its trust level, was considered valid by check_commit_signature(). This difference in behavior might induce users to erroneously assume that the trust level of a key in their keyring is always considered by Git, even for operations where it is not (e.g. during a verify-commit or verify-tag). The way it worked was by gpg-interface.c storing the result from the key/signature status *and* the lowest-two trust levels in the `result` member of the signature_check structure (the last of these status lines that were encountered got written to `result`). These are documented in GPG under the subsection `General status codes` and `Key related`, respectively [1]. The GPG documentation says the following on the TRUST_ status codes [1]: """ These are several similar status codes: - TRUST_UNDEFINED <error_token> - TRUST_NEVER <error_token> - TRUST_MARGINAL [0 [<validation_model>]] - TRUST_FULLY [0 [<validation_model>]] - TRUST_ULTIMATE [0 [<validation_model>]] For good signatures one of these status lines are emitted to indicate the validity of the key used to create the signature. The error token values are currently only emitted by gpgsm. """ My interpretation is that the trust level is conceptionally different from the validity of the key and/or signature. That seems to also have been the assumption of the old code in check_signature() where a result of 'G' (as in GOODSIG) and 'U' (as in TRUST_NEVER or TRUST_UNDEFINED) were both considered a success. The two cases where a result of 'U' had special meaning were in verify_merge_signature() (where this caused git to die()) and in format_commit_one() (where it affected the output of the %G? format specifier). I think it makes sense to refactor the processing of TRUST_ status lines such that users can configure a minimum trust level that is enforced globally, rather than have individual parts of git (e.g. merge) do it themselves (except for a grace period with backward compatibility). I also think it makes sense to not store the trust level in the same struct member as the key/signature status. While the presence of a TRUST_ status code does imply that the signature is good (see the first paragraph in the included snippet above), as far as I can tell, the order of the status lines from GPG isn't well-defined; thus it would seem plausible that the trust level could be overwritten with the key/signature status if they were stored in the same member of the signature_check structure. This patch introduces a new configuration option: gpg.minTrustLevel. It consolidates trust-level verification to gpg-interface.c and adds a new `trust_level` member to the signature_check structure. Backward-compatibility is maintained by introducing a special case in verify_merge_signature() such that if no user-configurable gpg.minTrustLevel is set, then the old behavior of rejecting TRUST_UNDEFINED and TRUST_NEVER is enforced. If, on the other hand, gpg.minTrustLevel is set, then that value overrides the old behavior. Similarly, the %G? format specifier will continue show 'U' for signatures made with a key that has a trust level of TRUST_UNDEFINED or TRUST_NEVER, even though the 'U' character no longer exist in the `result` member of the signature_check structure. A new format specifier, %GT, is also introduced for users that want to show all possible trust levels for a signature. Another approach would have been to simply drop the trust-level requirement in verify_merge_signature(). This would also have made the behavior consistent with other parts of git that perform signature verification. However, requiring a minimum trust level for signing keys does seem to have a real-world use-case. For example, the build system used by the Qubes OS project currently parses the raw output from verify-tag in order to assert a minimum trust level for keys used to sign git tags [2]. [1] https://git.gnupg.org/cgi-bin/gitweb.cgi?p=gnupg.git;a=blob;f=doc/doc/DETAILS;h=bd00006e933ac56719b1edd2478ecd79273eae72;hb=refs/heads/master [2] https://github.com/QubesOS/qubes-builder/blob/9674c1991deef45b1a1b1c71fddfab14ba50dccf/scripts/verify-git-tag#L43 Signed-off-by: Hans Jerry Illikainen <hji@dyntopia.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-07-25Merge branch 'rm/gpg-program-doc-fix'Libravatar Junio C Hamano1-1/+1
Docfix. * rm/gpg-program-doc-fix: gpg(docs): use correct --verify syntax
2019-07-12gpg(docs): use correct --verify syntaxLibravatar Robert Morgan1-1/+1
The gpg --verify usage example within the 'gpg.program' variable reference provides an incorrect example of the gpg --verify command arguments. The command argument order, when providing both a detached signature and data, should be signature first and data second: https://gnupg.org/documentation/manuals/gnupg/Operational-GPG-Commands.html Signed-off-by: Robert Morgan <robert.thomas.morgan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-07Documentation: turn middle-of-line tabs into spacesLibravatar Martin Ågren1-1/+1
These tabs happen to appear in columns where they don't stand out too much, so the diff here is non-obvious. Some of these are rendered differently by AsciiDoc and Asciidoctor (although the difference might be invisible!), which is how I found a few of them. The remainder were found using `git grep "[a-zA-Z.,)]$TAB[a-zA-Z]"`. Signed-off-by: Martin Ågren <martin.agren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-10-29config.txt: move gpg.* to a separate fileLibravatar Nguyễn Thái Ngọc Duy1-0/+20
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>