Class: Origami::Encryption::Standard::Dictionary

Inherits:
EncryptionDictionary show all
Defined in:
lib/origami/encryption.rb

Overview

Class defining a standard encryption dictionary.

Constant Summary

Constants included from StandardObject

StandardObject::DEFAULT_ATTRIBUTES

Constants inherited from Dictionary

Dictionary::TOKENS

Constants included from Object

Object::TOKENS

Instance Attribute Summary

Attributes inherited from Dictionary

#names_cache, #strings_cache, #xref_cache

Attributes included from Object

#file_offset, #generation, #no, #objstm_offset, #parent

Instance Method Summary collapse

Methods included from StandardObject

#do_type_check, #has_field?, included, #pre_build, #set_default_value, #set_default_values

Methods inherited from Dictionary

#[], #[]=, add_type_info, #cast_to, #copy, #delete, guess_type, #has_key?, hint_type, #initialize, #map!, #merge, #method_missing, native_type, parse, #to_obfuscated_str, #to_s

Methods included from Object

#<=>, #cast_to, #copy, #export, #indirect_parent, #initialize, #is_indirect?, #logicalize, #logicalize!, #native_type, native_type, parse, #pdf, #post_build, #pre_build, #reference, #resolve_all_references, #set_indirect, #set_pdf, #size, skip_until_next_obj, #solve, #to_o, #to_s, #type, typeof, #xrefs

Methods inherited from Hash

#to_o

Constructor Details

This class inherits a constructor from Origami::Dictionary

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Origami::Dictionary

Instance Method Details

#compute_owner_encryption_key(ownerpassword) ⇒ Object

Computes the key that will be used to encrypt/decrypt the document contents with owner password. Revision 5 and above.



1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
 
# File 'lib/origami/encryption.rb', line 1157

def compute_owner_encryption_key(ownerpassword)
  if self.R >= 5
    passwd = password_to_utf8(ownerpassword)

    oks = self.O[40, 8]

    if self.R == 5
      okey = Digest::SHA256.digest(passwd + oks + self.U)
    else
      okey = compute_hardened_hash(passwd, oks, self.U)
    end

    iv = ::Array.new(AES::BLOCKSIZE, 0).pack("C*")
    AES.new(okey, nil, false).decrypt(iv + self.OE.value)
  end
end

#compute_user_encryption_key(userpassword, fileid) ⇒ Object

Computes the key that will be used to encrypt/decrypt the document contents with user password.



1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
 
# File 'lib/origami/encryption.rb', line 1114

def compute_user_encryption_key(userpassword, fileid)
 
  if self.R < 5
    padded = pad_password(userpassword)
    padded.force_encoding('binary') if RUBY_VERSION >= '1.9'

    padded << self.O
    padded << [ self.P ].pack("i")
    
    padded << fileid
    
    encrypt_metadata = self.EncryptMetadata != false
    padded << [ -1 ].pack("i") if self.R >= 4 and not encrypt_metadata

    key = Digest::MD5.digest(padded)

    50.times { key = Digest::MD5.digest(key[0, self.Length / 8]) } if self.R >= 3

    if self.R == 2
      key[0, 5]
    elsif self.R >= 3
      key[0, self.Length / 8]
    end
  else
    passwd = password_to_utf8(userpassword)
    
    uks = self.U[40, 8]
    
    if self.R == 5
      ukey = Digest::SHA256.digest(passwd + uks)
    else
      ukey = compute_hardened_hash(passwd, uks)
    end
    
    iv = ::Array.new(AES::BLOCKSIZE, 0).pack("C*")
    AES.new(ukey, nil, false).decrypt(iv + self.UE.value)
  end
end

#is_owner_password?(pass, salt) ⇒ Boolean

Checks owner password. For version 2,3 and 4, salt is the document ID. For version 5, salt is (Owner Key Salt + U)

Returns:



1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
 
# File 'lib/origami/encryption.rb', line 1248

def is_owner_password?(pass, salt)

  if self.R < 5
    user_password = retrieve_user_password(pass)
    is_user_password?(user_password, salt)
  elsif self.R == 5
    ovs = self.O[32, 8]
    Digest::SHA256.digest(password_to_utf8(pass) + ovs + self.U) == self.O[0, 32]
  elsif self.R == 6
    ovs = self.O[32, 8]
    compute_hardened_hash(password_to_utf8(pass), ovs, self.U[0,48]) == self.O[0, 32]
  end
end

#is_user_password?(pass, salt) ⇒ Boolean

Checks user password. For version 2,3 and 4, salt is the document ID. For version 5 and 6, salt is the User Key Salt.

Returns:



1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
 
# File 'lib/origami/encryption.rb', line 1229

def is_user_password?(pass, salt)
  if self.R == 2 
    compute_user_password(pass, salt) == self.U
  elsif self.R == 3 or self.R == 4
    compute_user_password(pass, salt)[0, 16] == self.U[0, 16]
  elsif self.R == 5
    uvs = self.U[32, 8]
    Digest::SHA256.digest(password_to_utf8(pass) + uvs) == self.U[0, 32]
  elsif self.R == 6
    uvs = self.U[32, 8]
    compute_hardened_hash(password_to_utf8(pass), uvs) == self.U[0, 32]
  end
end

#pdf_version_required ⇒ Object

:nodoc:



1103
1104
1105
1106
1107
1108
1109
 
# File 'lib/origami/encryption.rb', line 1103

def pdf_version_required #:nodoc:
  if self.R > 5
    [ 1.7, 8 ]
  else
    super
  end
end

#retrieve_user_password(ownerpassword) ⇒ Object

Retrieve user password from owner password. Cannot be used with revision 5.



1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
 
# File 'lib/origami/encryption.rb', line 1266

def retrieve_user_password(ownerpassword)
  key = compute_owner_key(ownerpassword)

  if self.R == 2
    ARC4.decrypt(key, self.O)
  elsif self.R == 3 or self.R == 4
    user_password = ARC4.decrypt(xor(key, 19), self.O)
    19.times { |i| user_password = ARC4.decrypt(xor(key, 18-i), user_password) }
    
    user_password 
  end
end

#set_passwords(ownerpassword, userpassword, salt = nil) ⇒ Object

Set up document passwords.



1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
 
# File 'lib/origami/encryption.rb', line 1177

def set_passwords(ownerpassword, userpassword, salt = nil)
  if self.R < 5
    key = compute_owner_key(ownerpassword)
    upadded = pad_password(userpassword)
    
    owner_key = ARC4.encrypt(key, upadded)
    19.times { |i| owner_key = ARC4.encrypt(xor(key,i+1), owner_key) } if self.R >= 3
  
    self.O = owner_key
    self.U = compute_user_password(userpassword, salt)
  
  else
    upass = password_to_utf8(userpassword)
    opass = password_to_utf8(ownerpassword)

    uvs, uks, ovs, oks = ::Array.new(4) { Encryption.rand_bytes(8) }
    file_key = Encryption.strong_rand_bytes(32)
    iv = ::Array.new(AES::BLOCKSIZE, 0).pack("C*")
    
    if self.R == 5
      self.U = Digest::SHA256.digest(upass + uvs) + uvs + uks
      self.O = Digest::SHA256.digest(opass + ovs + self.U) + ovs + oks
      ukey = Digest::SHA256.digest(upass + uks)
      okey = Digest::SHA256.digest(opass + oks + self.U)
    else
      self.U = compute_hardened_hash(upass, uvs) + uvs + uks
      self.O = compute_hardened_hash(opass, ovs, self.U) + ovs + oks
      ukey = compute_hardened_hash(upass, uks)
      okey = compute_hardened_hash(opass, oks, self.U)
    end

    self.UE = AES.new(ukey, iv, false).encrypt(file_key)[iv.size, 32]
    self.OE = AES.new(okey, iv, false).encrypt(file_key)[iv.size, 32]

    perms = 
      [ self.P ].pack("V") +                              # 0-3
      [ -1 ].pack("V") +                                  # 4-7
      (self.EncryptMetadata == true ? "T" : "F") +        # 8
      "adb" +                                             # 9-11
      [ 0 ].pack("V")                                     # 12-15

    self.Perms = AES.new(file_key, iv, false).encrypt(perms)[iv.size, 16]

    file_key
  end
end