0fdf4da0e9
NAR info files in binary caches can now have a cryptographic signature that Nix will verify before using the corresponding NAR file. To create a private/public key pair for signing and verifying a binary cache, do: $ openssl genrsa -out ./cache-key.sec 2048 $ openssl rsa -in ./cache-key.sec -pubout > ./cache-key.pub You should also come up with a symbolic name for the key, such as "cache.example.org-1". This will be used by clients to look up the public key. (It's a good idea to number keys, in case you ever need to revoke/replace one.) To create a binary cache signed with the private key: $ nix-push --dest /path/to/binary-cache --key ./cache-key.sec --key-name cache.example.org-1 The public key (cache-key.pub) should be distributed to the clients. They should have a nix.conf should contain something like: signed-binary-caches = * binary-cache-public-key-cache.example.org-1 = /path/to/cache-key.pub If all works well, then if Nix fetches something from the signed binary cache, you will see a message like: *** Downloading ‘http://cache.example.org/nar/7dppcj5sc1nda7l54rjc0g5l1hamj09j-subversion-1.7.11’ (signed by ‘cache.example.org-1’) to ‘/nix/store/7dppcj5sc1nda7l54rjc0g5l1hamj09j-subversion-1.7.11’... On the other hand, if the signature is wrong, you get a message like NAR info file `http://cache.example.org/7dppcj5sc1nda7l54rjc0g5l1hamj09j.narinfo' has an invalid signature; ignoring Signatures are implemented as a single line appended to the NAR info file, which looks like this: Signature: 1;cache.example.org-1;HQ9Xzyanq9iV...muQ== Thus the signature has 3 fields: a version (currently "1"), the ID of key, and the base64-encoded signature of the SHA-256 hash of the contents of the NAR info file up to but not including the Signature line. Issue #75.
42 lines
1.1 KiB
Perl
42 lines
1.1 KiB
Perl
package Nix::Crypto;
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use strict;
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use MIME::Base64;
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use Nix::Store;
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use Nix::Config;
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use IPC::Open2;
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our @ISA = qw(Exporter);
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our @EXPORT = qw(signString isValidSignature);
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sub signString {
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my ($privateKeyFile, $s) = @_;
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my $hash = hashString("sha256", 0, $s);
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my ($from, $to);
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my $pid = open2($from, $to, $Nix::Config::openssl, "rsautl", "-sign", "-inkey", $privateKeyFile);
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print $to $hash;
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close $to;
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local $/ = undef;
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my $sig = <$from>;
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close $from;
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waitpid($pid, 0);
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die "$0: OpenSSL returned exit code $? while signing hash\n" if $? != 0;
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my $sig64 = encode_base64($sig, "");
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return $sig64;
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}
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sub isValidSignature {
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my ($publicKeyFile, $sig64, $s) = @_;
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my ($from, $to);
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my $pid = open2($from, $to, $Nix::Config::openssl, "rsautl", "-verify", "-inkey", $publicKeyFile, "-pubin");
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print $to decode_base64($sig64);
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close $to;
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my $decoded = <$from>;
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close $from;
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waitpid($pid, 0);
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return 0 if $? != 0;
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my $hash = hashString("sha256", 0, $s);
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return $decoded eq $hash;
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}
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1;
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