Class: HTAuth::Md5

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

Overview

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

Constant Summary collapse

DIGEST_LENGTH = 
16
PAD_LENGTH = 
6
PREFIX = 
"$apr1$".freeze
SALT_CHARS_STR = 
SALT_CHARS.join('')
ENTRY_REGEX = 
%r[
\A
#{Regexp.escape(PREFIX)}
[#{SALT_CHARS_STR}]{#{SALT_LENGTH}}
#{Regexp.escape("$")}
[#{SALT_CHARS_STR}]{#{DIGEST_LENGTH + PAD_LENGTH}}
\z
]x

Constants inherited from Algorithm

Algorithm::ARGON2, Algorithm::BCRYPT, Algorithm::CRYPT, Algorithm::DEFAULT, Algorithm::EXISTING, Algorithm::MD5, Algorithm::PLAINTEXT, Algorithm::SALT_CHARS, Algorithm::SALT_LENGTH, Algorithm::SHA1

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Algorithm

algorithm_from_field, algorithm_from_name, algorithm_name, #gen_salt, secure_compare, #to_64, #verify_password?

Methods included from DescendantTracker

#children, #find_child, #inherited

Constructor Details

#initialize(params = {}) ⇒ Md5

Returns a new instance of Md5.



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# File 'lib/htauth/md5.rb', line 31

def initialize(params = {})
  if existing = (params['existing'] || params[:existing]) then
    @salt = self.class.extract_salt_from_existing_password_field(existing)
  else
    @salt = params[:salt] || params['salt'] || gen_salt
  end
end

Class Method Details

.extract_salt_from_existing_password_field(existing) ⇒ Object 



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# File 'lib/htauth/md5.rb', line 26

def self.extract_salt_from_existing_password_field(existing)
  p = existing.split("$")
  return p[2]
end

.handles?(password_entry) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/htauth/md5.rb', line 22

def self.handles?(password_entry)
  ENTRY_REGEX.match?(password_entry)
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 40

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