Check the gpg signatures of .dsc files before unpacking. See

the upstream changelog for a full description of the semantics.
Based on a patch by Matt Zimmerman. Closes: #48711

ChangeLog

@@ -5,6 +5,16 @@
 	the .dsc when building. This also normalizes the
 	fields.
  
+2005-10-03  Matt Zimmerman  <mdz@debian.org>,
+	    Frank Lichtenheld  <djpig@debian.org>
+
+	* scripts/dpkg-source.pl: If gpg is installed, check
+	the signature of the .dsc file before unpacking.
+	Allow the unpacking to suceed if the .dsc is unsigned
+	but error out if the signature is bad. If gpg exits
+	with a code >2 (e.g. missing key), show the user the gpg
+	output but continue.
+
 2005-10-03  Frank Lichtenheld  <djpig@debian.org>
 
 	* scripts/dpkg-source.pl: Try to chown files extracted from

debian/changelog

@@ -11,6 +11,9 @@ dpkg (1.13.12~) unstable; urgency=low
   * Let dpkg-source -b check the build relation fields before
     putting them into the .dsc. As a side effect they also
     get normalized. Closes: #254449
+  * Check the gpg signatures of .dsc files before unpacking. See
+    the upstream changelog for a full description of the semantics.
+    Based on a patch by Matt Zimmerman. Closes: #48711
 
  --
 

scripts/dpkg-source.pl

@@ -516,7 +516,7 @@ if ($opmode eq 'build') {
     }
     exit(0);
 
-} else {
+} else { # -> opmode ne 'build'
 
     $sourcestyle =~ y/X/p/;
     $sourcestyle =~ m/[pun]/ ||
@@ -535,6 +535,32 @@ if ($opmode eq 'build') {
 	! -e $newdirectory || &error("unpack target exists: $newdirectory");
     }
 
+    my $is_signed = 0;
+    open(DSC,"< $dsc") || &error("cannot open .dsc file $dsc: $!");
+    while (<DSC>) {
+	next if /^\s*$/o;
+	$is_signed = 1 if /^-----BEGIN PGP SIGNED MESSAGE-----$/o;
+	last;
+    }
+    close(DSC);
+
+    if ($is_signed) {
+	if (-x '/usr/bin/gpg') {
+	    my $gpg_command = 'gpg -q --verify '.quotemeta($dsc).' 2>&1';
+	    my @gpg_output = `$gpg_command`;
+	    my $gpg_status = $? >> 8;
+	    if ($gpg_status) {
+		print STDERR join("",@gpg_output);
+		&error("failed to verify signature on $dsc")
+		    if ($gpg_status == 1);
+	    }
+	} else {
+	    &warn("could not verify signature on $dsc since gpg isn't installed");
+	}
+    } else {
+	&warn("extracting unsigned source package ($dsc)");
+    }
+
     open(CDATA,"< $dsc") || &error("cannot open .dsc file $dsc: $!");
     &parsecdata('S',-1,"source control file $dsc");
     close(CDATA);