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Diffstat (limited to 'doc/guix.texi')
| -rw-r--r-- | doc/guix.texi | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 0399c39814..c5b277d027 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -2143,6 +2143,8 @@ your system has unpatched security vulnerabilities. @cindex security @cindex digital signatures @cindex substitutes, authorization thereof +@cindex access control list (ACL), for substitutes +@cindex ACL (access control list), for substitutes To allow Guix to download substitutes from @code{hydra.gnu.org} or a mirror thereof, you must add its public key to the access control list (ACL) of archive @@ -2191,9 +2193,29 @@ The following files would be downloaded: This indicates that substitutes from @code{hydra.gnu.org} are usable and will be downloaded, when possible, for future builds. -Guix ignores substitutes that are not signed, or that are not signed by -one of the keys listed in the ACL. It also detects and raises an error -when attempting to use a substitute that has been tampered with. +Guix detects and raises an error when attempting to use a substitute +that has been tampered with. Likewise, it ignores substitutes that are +not signed, or that are not signed by one of the keys listed in the ACL. + +There is one exception though: if an unauthorized server provides +substitutes that are @emph{bit-for-bit identical} to those provided by +an authorized server, then the unauthorized server becomes eligible for +downloads. For example, assume we have chosen two substitute servers +with this option: + +@example +--substitute-urls="https://a.example.org https://b.example.org" +@end example + +@noindent +@cindex reproducible builds +If the ACL contains only the key for @code{b.example.org}, and if +@code{a.example.org} happens to serve the @emph{exact same} substitutes, +then Guix will download substitutes from @code{a.example.org} because it +comes first in the list and can be considered a mirror of +@code{b.example.org}. In practice, independent build machines usually +produce the same binaries, thanks to bit-reproducible builds (see +below). @vindex http_proxy Substitutes are downloaded over HTTP or HTTPS. |