rubyでMD5

#!/usr/bin/ruby

pass = "hoge"
SALTS = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
puts pass

salt = ""
8.times do
  salt += SALTS[rand 64]
end
puts salt

ps = pass.crypt(salt)
puts ps

print "YES\n" if pass.crypt(ps) == ps
puts pass.crypt(ps)

http://www.namaraii.com/rubytips/?%CA%B8%BB%FA%CE%F3
プログラミング言語 Ruby リファレンスマニュアル