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 = 
"$apr1$"
SALT_CHARS_STR = 
SALT_CHARS.join
ENTRY_REGEX = 
/
\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, #to64, #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 32

def initialize(params = {})
  super()
  @salt = if (existing = params["existing"] || params[:existing])
            self.class.extract_salt_from_existing_password_field(existing)
          else
            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 27

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

.handles?(password_entry) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/htauth/md5.rb', line 23

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 42

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.positive?
    slice_size = [l, DIGEST_LENGTH].min
    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.allbits?(1) ? password : pd[0, DIGEST_LENGTH])
    (ctx << @salt) unless (x % 3).zero?
    (ctx << password) unless (x % 7).zero?
    ctx << (x.nobits?(1) ? 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 << to64(l, 4)

  l = (pd[1] << 16) | (pd[7] << 8) | pd[13]
  encoded_password << to64(l, 4)

  l = (pd[2] << 16) | (pd[8] << 8) | pd[14]
  encoded_password << to64(l, 4)

  l = (pd[3] << 16) | (pd[9] << 8) | pd[15]
  encoded_password << to64(l, 4)

  l = (pd[4] << 16) | (pd[10] << 8) | pd[5]
  encoded_password << to64(l, 4)
  encoded_password << to64(pd[11], 2)

  encoded_password
end