Description: allow quotes around "enveloped-data" as created by MIME::Entity
 This patch was picked from the upstream RT, where it has been lingering
 for 18 months without receiving a comment. It looks like it could be useful
 for our users as well.
Origin: https://rt.cpan.org/Public/Bug/Display.html?id=53620

--- a/lib/SMIME.pm
+++ b/lib/SMIME.pm
@@ -87,7 +87,7 @@
 
 	my $ctype = $this->_getContentType($mime);
 	if($ctype =~ m!^application/(?:x-)?pkcs7-mime!
-	&& ($ctype !~ m!smime-type=! || $ctype =~ m!smime-type=enveloped-data!)) {
+	&& ($ctype !~ m!smime-type=! || $ctype =~ m!smime-type="?enveloped-data"?!)) {
 		# smime-typeが存在しないか、それがenveloped-dataである。
 		1;
 	} else {