Adding password hash computation

2 files changed, 61 insertions, 40 deletions

diff --git a/lib/axlsx/workbook/worksheet/sheet_protection.rb b/lib/axlsx/workbook/worksheet/sheet_protection.rb
index cc1eaf2b..2853848e 100644
--- a/lib/axlsx/workbook/worksheet/sheet_protection.rb
+++ b/lib/axlsx/workbook/worksheet/sheet_protection.rb
@@ -4,14 +4,6 @@ module Axlsx
   # The SheetProtection object manages worksheet protection options per sheet.
   class SheetProtection
 
-    # Specifies the specific cryptographic hashing algorithm which shall be used along
-    # with the salt attribute and input password in order to compute the hash value.
-    # This value is automatically set to 'SHA-1' when password= is called.
-    # @note only SHA-1 is supported.
-    # @return [String]
-    attr_reader :algorithm_name
-
-
     # If 1 or true then AutoFilters should not be allowed to operate when the sheet is protected.
     # If 0 or false then AutoFilters should be allowed to operate when the sheet is protected.
     # @return [Boolean]
@@ -115,11 +107,12 @@ module Axlsx
     # @return [Boolean]
     # @default true
     attr_reader :sort
-
-    # Specifies the number of times the hashing function shall be iteratively run
-    # @return [Integer]
-    # @default 10000
-    attr_reader :spin_count
+    
+    
+    # Password hash
+    # @return [String]
+    # @default nil
+    attr_reader :password
 
     # Creates a new SheetProtection instance
     # @option options [Boolean] sheet @see SheetProtection#sheet
@@ -143,6 +136,8 @@ module Axlsx
     def initialize(options={})
       @objects = @scenarios = @select_locked_cells = @select_unlocked_cells = false
       @sheet = @format_cells = @format_rows = @format_columns = @insert_columns = @insert_rows = @insert_hyperlinks = @delete_columns = @delete_rows = @sort = @auto_filter = @pivot_tables = true
+      @password = nil
+      
       options.each do |o|
         self.send("#{o[0]}=", o[1]) if self.respond_to? "#{o[0]}="
       end
@@ -159,22 +154,51 @@ module Axlsx
      end
 
      def password=(v)
-       @algorithm_name = v == nil ? nil : 'SHA-1'
-       @salt_value = @spin_count = @hash_value = v if v == nil
        return if v == nil
-       require 'digest/sha1'
-       @spin_count = 10000
-       @salt_value = Digest::SHA1.hexdigest(rand(36**8).to_s(36))
-       @hash_value = nil
-       @spin_count.times do |count|
-         @hash_value = Digest::SHA1.hexdigest((@hash_value || (@salt_value + v.to_s)) + count.to_s.bytes.to_a.pack('l'))
-       end
+        @hash_value = create_password_hash(v)
      end
 
      def to_xml_string(str = '')
        str << '<sheetProtection '
        str << instance_values.map{ |k,v| k.gsub(/_(.)/){ $1.upcase } << %{="#{v.to_s}"} }.join(' ')
        str << '/>'
-     end 
+     end
+  
+  private
+    # Creates a password hash for a given password
+    # @return [String]
+    def create_password_hash(password)
+      encoded_password = encode_password(password)
+      
+      password_as_hex = [encoded_password].pack("v")
+      password_as_string = password_as_hex.unpack("H*").first.upcase
+      
+      password_as_string[2..3] + password_as_string[0..1]
+    end
+    
+    
+    # Encodes a given password
+    # Based on the algorithm provided by Daniel Rentz of OpenOffice.
+    # http://www.openoffice.org/sc/excelfileformat.pdf, Revision 1.42, page 115 (21.05.2012)
+    # @return [String]
+    def encode_password(password)
+      i = 0
+      chars = password.split(//)
+      count = chars.size
+  
+      chars.collect! do |char|
+        i += 1
+        char     = char.ord << i
+        low_15   = char & 0x7fff
+        high_15  = char & 0x7fff << 15
+        high_15  = high_15 >> 15
+        char     = low_15 | high_15
+      end
+      
+      encoded_password  = 0x0000
+      chars.each { |c| encoded_password ^= c }
+      encoded_password ^= count
+      encoded_password ^= 0xCE4B
+    end
   end
 end
diff --git a/test/workbook/worksheet/tc_sheet_protection.rb b/test/workbook/worksheet/tc_sheet_protection.rb
index d6b16534..28185775 100644
--- a/test/workbook/worksheet/tc_sheet_protection.rb
+++ b/test/workbook/worksheet/tc_sheet_protection.rb
@@ -2,10 +2,6 @@
 require 'tc_helper.rb'
 
 # <xsd:complexType name="CT_SheetProtection">
-# <xsd:attribute name="algorithmName" type="s:ST_Xstring" use="optional"/>
-# <xsd:attribute name="hashValue" type="xsd:base64Binary" use="optional"/>
-# <xsd:attribute name="saltValue" type="xsd:base64Binary" use="optional"/>
-# <xsd:attribute name="spinCount" type="xsd:unsignedInt" use="optional"/>
 # <xsd:attribute name="sheet" type="xsd:boolean" use="optional" default="false"/>
 # <xsd:attribute name="objects" type="xsd:boolean" use="optional" default="false"/>
 # <xsd:attribute name="scenarios" type="xsd:boolean" use="optional" default="false"/>
@@ -22,41 +18,42 @@ require 'tc_helper.rb'
 # <xsd:attribute name="autoFilter" type="xsd:boolean" use="optional" default="true"/>
 # <xsd:attribute name="pivotTables" type="xsd:boolean" use="optional" default="true"/>
 # <xsd:attribute name="selectUnlockedCells" type="xsd:boolean" use="optional" default="false"/>
+# <xsd:attribute name="password" type="xsd:string" use="optional" default="nil"/>
 # </xsd:complexType>
  
 class TestSheetProtection < Test::Unit::TestCase
   def setup
     #inverse defaults
-    @options = { :sheet => false, :objects => true, :scenarios => true, :format_cells => false,
-                :format_columns => false, :format_rows => false, :insert_columns => false, :insert_rows => false,
-                :insert_hyperlinks => false, :delete_columns => false, :delete_rows => false, :select_locked_cells => true,
-                :sort => false, :auto_filter => false, :pivot_tables => false, :select_unlocked_cells => true }
+    @boolean_options = { :sheet => false, :objects => true, :scenarios => true, :format_cells => false,
+                         :format_columns => false, :format_rows => false, :insert_columns => false, :insert_rows => false,
+                         :insert_hyperlinks => false, :delete_columns => false, :delete_rows => false, :select_locked_cells => true,
+                         :sort => false, :auto_filter => false, :pivot_tables => false, :select_unlocked_cells => true }
+
+    @string_options = { :password => nil }
+    
+    @options = @boolean_options.merge(@string_options)
+             
     @sp = Axlsx::SheetProtection.new(@options)
   end
 
   def test_initialize
     sp = Axlsx::SheetProtection.new
-    @options.each do |key, value|
+    @boolean_options.each do |key, value|
       assert_equal(!value, sp.send(key.to_sym), "initialized default #{key} should be #{!value}")
       assert_equal(value, @sp.send(key.to_sym), "initialized options #{key} should be #{value}")
     end
-    { :algorithm_name => nil }.each do |key, value|
-      assert_equal(value, @sp.send(key.to_sym), "initialized default #{key} should be #{value}")
-      assert_equal(value, sp.send(key.to_sym), "initialized default #{key} should be #{value}")
-    end 
   end
 
   def test_boolean_attribute_validation
-    @options.each do |key, value|
+    @boolean_options.each do |key, value|
       assert_raise(ArgumentError, "#{key} must be boolean") { @sp.send("#{key}=".to_sym, 'A') }
       assert_nothing_raised { @sp.send("#{key}=".to_sym, true) }
       assert_nothing_raised { @sp.send("#{key}=".to_sym, true) }
     end
   end
-  
- 
+
   def test_to_xml_string
-    @sp.password = 'fish'
+    @sp.password = 'fish' # -> CA3F
     doc = Nokogiri::XML(@sp.to_xml_string)
     @options.each do |key, value|
       assert(doc.xpath("//sheetProtection[@#{key.to_s.gsub(/_(.)/){ $1.upcase }}='#{value}']"))