Class: HTAuth::Md5

Inherits:
Algorithm show all
Defined in:
lib/htauth/md5.rb

Overview

an implementation of the MD5 based encoding algorithm as used in the apache htpasswd -m option

Constant Summary collapse

DIGEST_LENGTH = 
16

Constants inherited from Algorithm

Algorithm::DEFAULT, Algorithm::EXISTING, Algorithm::SALT_CHARS

Instance Method Summary collapse

Methods inherited from Algorithm

algorithm_from_name, algorithms_from_field, #gen_salt, inherited, sub_klasses, #to_64

Constructor Details

#initialize(params = {}) ⇒ Md5

Returns a new instance of Md5.



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# File 'lib/htauth/md5.rb', line 12

def initialize(params = {})
  @salt = params['salt'] || params[:salt] || gen_salt
end

Instance Method Details

#encode(password) ⇒ Object

this algorigthm pulled straight from apr_md5_encode() and converted to ruby syntax



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# File 'lib/htauth/md5.rb', line 21

def encode(password)
  primary = ::Digest::MD5.new
  primary << password
  primary << prefix
  primary << @salt

  md5_t = ::Digest::MD5.digest("#{password}#{@salt}#{password}")

  l = password.length
  while l > 0 do
    slice_size = ( l > DIGEST_LENGTH ) ? DIGEST_LENGTH : l
    primary << md5_t[0, slice_size]
    l -= DIGEST_LENGTH
  end

  # weirdness
  l = password.length
  while l != 0
    case (l & 1)
    when 1
      primary << 0.chr
    when 0
      primary << password[0,1]
    end
    l >>= 1
  end

  pd = primary.digest

  encoded_password = "#{prefix}#{@salt}$"

  # apr_md5_encode has this comment about a 60Mhz Pentium above this loop.
  1000.times do |x|
    ctx = ::Digest::MD5.new
    ctx << (( ( x & 1 ) == 1 ) ? password : pd[0,DIGEST_LENGTH])
    (ctx << @salt) unless ( x % 3 ) == 0
    (ctx << password) unless ( x % 7 ) == 0
    ctx << (( ( x & 1 ) == 0 ) ? password : pd[0,DIGEST_LENGTH])
    pd = ctx.digest
  end


  pd = pd.bytes.to_a

  l = (pd[ 0]<<16) | (pd[ 6]<<8) | pd[12]
  encoded_password << to_64(l, 4)

  l = (pd[ 1]<<16) | (pd[ 7]<<8) | pd[13]
  encoded_password << to_64(l, 4)

  l = (pd[ 2]<<16) | (pd[ 8]<<8) | pd[14]
  encoded_password << to_64(l, 4)

  l = (pd[ 3]<<16) | (pd[ 9]<<8) | pd[15]
  encoded_password << to_64(l, 4)

  l = (pd[ 4]<<16) | (pd[10]<<8) | pd[ 5]
  encoded_password << to_64(l, 4)
  encoded_password << to_64(pd[11],2)

  return encoded_password
end

#prefix ⇒ Object 



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# File 'lib/htauth/md5.rb', line 16

def prefix
  "$apr1$"
end