| Subject: | numeric key breaks xor |
| Date: | Thu, 4 Dec 2014 11:38:22 +0000 |
| To: | bug-Digest-HMAC [...] rt.cpan.org |
| From: | Zefram <zefram [...] fysh.org> |
$ perl -MDigest::HMAC -MDigest::MD5 -lwe 'print +Digest::HMAC->new("1", "Digest::MD5")->hexdigest'
db9409c5b03f0a3b327438744001d7dd
$ perl -MDigest::HMAC -MDigest::MD5 -lwe 'print +Digest::HMAC->new(1, "Digest::MD5")->hexdigest'
Argument "\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\..." isn't numeric in bitwise xor (^) at /opt/perl-5.18.2/lib/site_perl/5.18.2/Digest/HMAC.pm line 16.
970b9decb3bba4b681ecee5b41e77ebb
Passing in the key as a numeric scalar breaks the computation, because
Digest::HMAC is internally passing the key scalar to Perl's native xor op,
which does different things depending on the scalar type. It's one of
the few places where the usual coercion of number to string isn't applied.
Digest::HMAC should stringify the supplied key to make sure the operands
for xor are always pure strings.
-zefram