md5 hashing in j

hashes.ijs

0 : 0
Can you crack Aaron’s password hash? He seems to like
simple passwords. I’m sure he’ll use his name and birthday                       | in it. Hint: Aaron writes important dates as YYYYMMDD
rather than YYYY-MM-DD or any other special character                            | separator. Hash: 7f4986da7d7b52fa81f98278e6ec9dcb.
Author: moat, Pacific Northwest National Laboratory
)

y=:":"0 (1900 + i.120)
m=:(i.11) { ('0' ,"1 ":"0 (1+i.9)) , ('1' ,"1 ":"0 (1+i.9))
d=:('0' ,"1 ":"0 (1+i.9)) , (":"0) 10+i.22

md5=:15&(128!:6)
NB.    md5 'foo'
NB. acbd18db4cc2f85cedef654fccc4a4d8

require 'format/printf'
dates=:,/ (1+i.31) ,"1 0/~ ,/ (1900+i.120) ,"0/ (1+i.12)
sdates =: '%d%02d%02d' sprintf dates

passwords=:'Aaron',"1 1 sdates
hashes=:md5 passwords

NB. First 10 hashes;
(i.10) { hashes
98973283b3af42f7aa10372df7d62652
a7460a6feb4205c9ae7ca77f867fdc3b
1545446bd3903d812f5a5826727ef53a
fdcba9439b2d86e1b59a6edb4af37a52
7e7ad7a858a4368351846dfa8044e2f6
a9dfffd098cd64b5a8c26575a43ecc26
0897c50557a8202f26083f2bf3d0c7a2
bbb63a0d9c3fa5ea9ead2c6abbdb5017
54fe0d6b2c91024ca6d2762e629b9559
3555724e95175a629e15d90df1c25ccc
...

require 'format/printf'
dates=:,/ (1+i.31) ,"1 0/~ ,/ (1900+i.120) ,"0/ (1+i.12)
sdates =: '%d%02d%02d' sprintf dates

passwords=:'Aaron',"1 1 sdates
hashes=:md5 passwords

NB. Compare the needle with the haystack.
NB. This compares each character and returns a list of bools for each comparison.
NB. Then we sum the bits together.
sums =: +/"1 '7f4986da7d7b52fa81f98278e6ec9dcb' ="1 1 hashes

NB. Find the index of a match
sums i: 32

NB. Grab the matching password
(sums i: 32) { passwords