Class: OoxmlDecrypt::EncryptedKey

Inherits:
KeyInfoBase show all
Defined in:
lib/ooxml_decrypt/encrypted_key.rb

Constant Summary collapse

ENCRYPTED_VERIFIER_HASH_INPUT_BLOCK_KEY =

Integrity-verification constants (not currently used)

"FEA7D2763B4B9E79".unhexify
ENCRYPTED_VERIFIER_HASH_VALUE_BLOCK_KEY = 
"D7AA0F6D3061344E".unhexify
ENCRYPTED_KEY_VALUE_BLOCK_KEY =

Static key used in decrypting the key-encryption key

"146E0BE7ABACD0D6".unhexify

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from KeyInfoBase

opts_from_xml_node

Constructor Details

#initialize(opts) ⇒ EncryptedKey

Returns a new instance of EncryptedKey.



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# File 'lib/ooxml_decrypt/encrypted_key.rb', line 11

def initialize(opts)
  @spin_count = opts.delete(:spin_count)
  @encrypted_key = opts.delete(:encrypted_key)
  super(opts)
end

Class Method Details

.from_xml(xml_doc) ⇒ Object

Extracts key-encryption-key data parameters from the given XML document and populates a new EncryptedKey object.

Parameters:

  • xml_doc (Nokogiri::XML::Document) —

    The EncryptionInfo section of the encrypted OOXML document



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# File 'lib/ooxml_decrypt/encrypted_key.rb', line 21

def self.from_xml(xml_doc)
  ke_node = xml_doc.at_css("keyEncryptor")
  raise "Expected only one child for keyEncryptor" unless ke_node.children.count == 1

  ek_node = ke_node.child
  opts = KeyInfoBase.opts_from_xml_node(ek_node)
  opts[:spin_count] = ek_node["spinCount"].to_i
  opts[:encrypted_key] = ek_node["encryptedKeyValue"].base64_decode

  return self.new(opts)
end

Instance Method Details

#key(password) ⇒ String

Decrypts the key-encryption key using the given password

Parameters:

  • password (String) —

    Password as a UTF-16-formatted binary string (e.g. the password ‘password’ should be passed as “p0a0s0s0w0r0d0”)

Returns:

  • (String) —

    The key-encryption key



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# File 'lib/ooxml_decrypt/encrypted_key.rb', line 48

def key(password)
  decrypt(@encrypted_key, key_encryption_key(password))
end