Really short(6chars) hash method

short_hash.rb

# Really short hash, (no extra collisions besides the known CRC32 )
# Correct term for this encoding should be "Trimmed Urlsafe Base Encoded CRC32 Hash"  or TUBECH?.. two-bitch encoding, lol.

# String.send(:include , ShortHash)
# "Hello World".short_hash # => "VrEXSg"

module ShortHash
  require 'base64'
  

  def ShortHash::base64_hash(str)
    # doing gsub('+','-').gsub('/','_') because I could not find Base64.urlsafe_base64 encoding in Ruby 1.8.7
    # doing gsub(/==\n?$/,'') to remove unnecessary base64 padding wich will always be '==\n' due to the constant crc32 length.
    Base64.encode64([str.hash].pack('l')).gsub('+','-').gsub('/','_').gsub(/==\n?$/,'')
  end

  def short_hash
   ShortHash::base64_crc32(self)
  end

  def ShortHash::base64_sha1(str)
    Base64.encode64(Digest::SHA1.digest(str)).gsub('+','-').gsub('/','_').gsub(/=\n?$/,'')
  end
  def short_sha
    ShortHash::base64_sha1(self)
  end
end