From: Fabian Stelzer <fs@xxxxxxxxxxxx> Signed-off-by: Fabian Stelzer <fs@xxxxxxxxxxxx> --- Documentation/config/gpg.txt | 39 +++++++++++++++++++++++++++++++++-- Documentation/config/user.txt | 6 ++++++ 2 files changed, 43 insertions(+), 2 deletions(-) diff --git a/Documentation/config/gpg.txt b/Documentation/config/gpg.txt index d94025cb368..dc790512e86 100644 --- a/Documentation/config/gpg.txt +++ b/Documentation/config/gpg.txt @@ -11,13 +11,13 @@ gpg.program:: gpg.format:: Specifies which key format to use when signing with `--gpg-sign`. - Default is "openpgp" and another possible value is "x509". + Default is "openpgp". Other possible values are "x509", "ssh". 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". + 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 @@ -33,3 +33,38 @@ gpg.minTrustLevel:: * `marginal` * `fully` * `ultimate` + +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@xxxxxxxxxxx,user2@xxxxxxxxxxx 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. +Therefore to only mark fully trusted keys as verified set gpg.minTrustLevel to `fully`. +Otherwise valid but untrusted signatures will still verify but show no principal +name of the signer. ++ +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. ++ +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. diff --git a/Documentation/config/user.txt b/Documentation/config/user.txt index 59aec7c3aed..b3c2f2c541e 100644 --- a/Documentation/config/user.txt +++ b/Documentation/config/user.txt @@ -36,3 +36,9 @@ user.signingKey:: commit, you can override the default selection with this variable. This option is passed unchanged to gpg's --local-user parameter, so you may specify a key using any method that gpg supports. + If gpg.format is set to "ssh" this can contain the literal ssh public + key (e.g.: "ssh-rsa XXXXXX identifier") or a file which contains it and + corresponds to the private key used for signing. The private key + needs to be available via ssh-agent. Alternatively it can be set to + a file containing a private key directly. If not set git will call + "ssh-add -L" and try to use the first key available. -- gitgitgadget
