Password class for DSLocalRrecord

password.rb

require 'pp'
require 'osx/cocoa'
include OSX

class DSLocalPassword
  
  attr_reader :content
  
  @@macosx_major_version = 10.7
  @@password_create_methods = {
    'PLAINTEXT' => :password_plain,
    'SHA1' => :password_plain,
    'SALTED-SHA512' => :password_salted_sha512,
    'SALTED-SHA512-PBKDF2' => :password_salted_sha512_pbkdf2,
  }
  
  def initialize(args)
    @label = args[:label]
    @content = self.send(@@password_create_methods[@label].to_sym, args)
  end
  
  private
  
  def password_salted_sha512(args)
    data = encode_hex_to_nsdata(args[:hash])
    serialize_shadow_hash_data(args[:label], data)
  end

  def password_salted_sha512_pbkdf2(args)
    label = args[:label]
    data = NSMutableDictionary.new
    # This is going to sound crazy, but I think the order in which these
    # keys are added to dict matters. If I add 'iterations' before the others,
    # after the dict is serialized, it fails the equality test. Very bizarre.
    data["entropy"] = encode_hex_to_nsdata(args[:entropy])
    data["salt"] = encode_hex_to_nsdata(args[:salt])
    data["iterations"] = args[:iterations]
    serialize_shadow_hash_data(label, data)
  end
  
  # Convert hex string to ASCII
  def convert_hex_to_ascii(hex)
    hex.scan(/../).collect { |byte| byte.hex.chr }.join
  end
  
  def encode_hex_to_nsdata(hex)
    ascii = convert_hex_to_ascii(hex)
    data = NSData.alloc.initWithBytes_length_(ascii, ascii.length)    
  end
  
  # Returns PropertyList
  def serialize_shadow_hash_data(label, data)
    plist = NSMutableDictionary.new
    plist[label] = data
    NSPropertyListSerialization.objc_send(
      :dataFromPropertyList, plist,
      :format, NSPropertyListBinaryFormat_v1_0,
      :errorDescription, nil
    )
  end
  
  # The salted SHA1 hash starts at character 169, and is 48 characters long:
  # The first 8 characters are the hex value of a 4-byte salt.
  
end

# Password.new(:label => 'SALTED-SHA512', :foo => 'whatever')