Verifying a bcrypt hash?

Question

In this question:

Can someone explain how BCrypt verifies a hash?

Ian Boyd writes at the end of his answer:

Armed with this knowledge, you can now verify a password correctbatteryhorsestapler against the saved hash: $2a$12$mACnM5lzNigHMaf7O1py1OLCBgGL4tYUF0N/4rS9CwDsI7ytwL4D6

I am using the following Perl program to attempt to verify this hash:

use Crypt::Eksblowfish::Bcrypt qw(bcrypt);
my $password = "correctbatteryhorsestapler";
my $hash = '$2a$12$mACnM5lzNigHMaf7O1py1OLCBgGL4tYUF0N/4rS9CwDsI7ytwL4D6';

print "Verifying password $password<br>with hash $hash<BR><BR>";

my $new_hash = bcrypt($password,$hash);

print "<pre>Original hash: " . $hash . "<br>" . "New hash:      " . $new_hash . "</pre><br>";

if ($hash ne $new_hash) {
    print "No match.";
}

The output of my program is as follows:

Verifying password correctbatteryhorsestapler
with hash $2a$12$mACnM5lzNigHMaf7O1py1OLCBgGL4tYUF0N/4rS9CwDsI7ytwL4D6

Original hash: $2a$12$mACnM5lzNigHMaf7O1py1OLCBgGL4tYUF0N/4rS9CwDsI7ytwL4D6
New hash:      $2a$12$mACnM5lzNigHMaf7O1py1O3vlf6.BA8k8x3IoJ.Tq3IB/2e7g61Km


No match.

I wonder if, based on the information above, anyone can tell me what I am doing wrong with my Perl script (why it doesn't correctly validate the password)? If I use the hash my system generates, I do get a match:

Verifying password correctbatteryhorsestapler
with hash $2a$12$mACnM5lzNigHMaf7O1py1O3vlf6.BA8k8x3IoJ.Tq3IB/2e7g61Km

Original hash: $2a$12$mACnM5lzNigHMaf7O1py1O3vlf6.BA8k8x3IoJ.Tq3IB/2e7g61Km
New hash:      $2a$12$mACnM5lzNigHMaf7O1py1O3vlf6.BA8k8x3IoJ.Tq3IB/2e7g61Km

I get the same result on two different systems (one CentOS running eksblowfish 0.009 and the other Win7 64-bit running eksblowfish 0.007, both running Perl 5.8.8).

I learn by doing, so I am hoping to understand why this isn't working for me.

Answer 1

The answer is that it's my fault. i gave you the wrong hash in the question for correctbatteryhorsestapler.

i picked a real hash; but not wanting to give away the password i changed it to a reference to XKCD.

i should have taken the extra moments to generate an actual hash for correctbatteryhorsestapler:

$2a$12$mACnM5lzNigHMaf7O1py1O3vlf6.BA8k8x3IoJ.Tq3IB/2e7g61Km

My fault for the confusion. In the original question i meant it as now you are ready to go out into the world, it wasn't meant to be an actual test vector.

---

You might want to look at some actual known test vectors:

('',                                   '$2a$06$DCq7YPn5Rq63x1Lad4cll.',    '$2a$06$DCq7YPn5Rq63x1Lad4cll.TV4S6ytwfsfvkgY8jIucDrjc8deX1s.'),
('',                                   '$2a$08$HqWuK6/Ng6sg9gQzbLrgb.',    '$2a$08$HqWuK6/Ng6sg9gQzbLrgb.Tl.ZHfXLhvt/SgVyWhQqgqcZ7ZuUtye'),
('',                                   '$2a$10$k1wbIrmNyFAPwPVPSVa/ze',    '$2a$10$k1wbIrmNyFAPwPVPSVa/zecw2BCEnBwVS2GbrmgzxFUOqW9dk4TCW'),
('',                                   '$2a$12$k42ZFHFWqBp3vWli.nIn8u',    '$2a$12$k42ZFHFWqBp3vWli.nIn8uYyIkbvYRvodzbfbK18SSsY.CsIQPlxO'),
('a',                                  '$2a$06$m0CrhHm10qJ3lXRY.5zDGO',    '$2a$06$m0CrhHm10qJ3lXRY.5zDGO3rS2KdeeWLuGmsfGlMfOxih58VYVfxe'),
('a',                                  '$2a$08$cfcvVd2aQ8CMvoMpP2EBfe',    '$2a$08$cfcvVd2aQ8CMvoMpP2EBfeodLEkkFJ9umNEfPD18.hUF62qqlC/V.'),
('a',                                  '$2a$10$k87L/MF28Q673VKh8/cPi.',    '$2a$10$k87L/MF28Q673VKh8/cPi.SUl7MU/rWuSiIDDFayrKk/1tBsSQu4u'),
('a',                                  '$2a$12$8NJH3LsPrANStV6XtBakCe',    '$2a$12$8NJH3LsPrANStV6XtBakCez0cKHXVxmvxIlcz785vxAIZrihHZpeS'),
('abc',                                '$2a$06$If6bvum7DFjUnE9p2uDeDu',    '$2a$06$If6bvum7DFjUnE9p2uDeDu0YHzrHM6tf.iqN8.yx.jNN1ILEf7h0i'),
('abc',                                '$2a$08$Ro0CUfOqk6cXEKf3dyaM7O',    '$2a$08$Ro0CUfOqk6cXEKf3dyaM7OhSCvnwM9s4wIX9JeLapehKK5YdLxKcm'),
('abc',                                '$2a$10$WvvTPHKwdBJ3uk0Z37EMR.',    '$2a$10$WvvTPHKwdBJ3uk0Z37EMR.hLA2W6N9AEBhEgrAOljy2Ae5MtaSIUi'),
('abc',                                '$2a$12$EXRkfkdmXn2gzds2SSitu.',    '$2a$12$EXRkfkdmXn2gzds2SSitu.MW9.gAVqa9eLS1//RYtYCmB1eLHg.9q'),
('abcdefghijklmnopqrstuvwxyz',         '$2a$06$.rCVZVOThsIa97pEDOxvGu',    '$2a$06$.rCVZVOThsIa97pEDOxvGuRRgzG64bvtJ0938xuqzv18d3ZpQhstC'),
('abcdefghijklmnopqrstuvwxyz',         '$2a$08$aTsUwsyowQuzRrDqFflhge',    '$2a$08$aTsUwsyowQuzRrDqFflhgekJ8d9/7Z3GV3UcgvzQW3J5zMyrTvlz.'),
('abcdefghijklmnopqrstuvwxyz',         '$2a$10$fVH8e28OQRj9tqiDXs1e1u',    '$2a$10$fVH8e28OQRj9tqiDXs1e1uxpsjN0c7II7YPKXua2NAKYvM6iQk7dq'),
('abcdefghijklmnopqrstuvwxyz',         '$2a$12$D4G5f18o7aMMfwasBL7Gpu',    '$2a$12$D4G5f18o7aMMfwasBL7GpuQWuP3pkrZrOAnqP.bmezbMng.QwJ/pG'),
('~!@#$%^&*()      ~!@#$%^&*()PNBFRD', '$2a$06$fPIsBO8qRqkjj273rfaOI.',    '$2a$06$fPIsBO8qRqkjj273rfaOI.HtSV9jLDpTbZn782DC6/t7qT67P6FfO'),
('~!@#$%^&*()      ~!@#$%^&*()PNBFRD', '$2a$08$Eq2r4G/76Wv39MzSX262hu',    '$2a$08$Eq2r4G/76Wv39MzSX262huzPz612MZiYHVUJe/OcOql2jo4.9UxTW'),
('~!@#$%^&*()      ~!@#$%^&*()PNBFRD', '$2a$10$LgfYWkbzEvQ4JakH7rOvHe',    '$2a$10$LgfYWkbzEvQ4JakH7rOvHe0y8pHKF9OaFgwUZ2q7W2FFZmZzJYlfS'),
('~!@#$%^&*()      ~!@#$%^&*()PNBFRD', '$2a$12$WApznUOJfkEGSmYRfnkrPO',    '$2a$12$WApznUOJfkEGSmYRfnkrPOr466oFDCaj4b6HY3EXGvfxm43seyhgC')

There are also tests that make sure that it doesn't fail on Unicode characters. There was a bug in an implementation somewhere that crashed when given UTF-8:

• Password: ππππππππ Greek Small Letter Pi (U+03C0), eight repetitions

For which an actual hash is:

$2a$10$.TtQJ4Jr6isd4Hp.mVfZeuh6Gws4rOQ/vdBczhDx.19NFK0Y84Dle