2.2.6 Encryption and Obfuscation (Password to Open)


A file in Word Binary File Format can be password protected by using one of the following mechanisms:

  • XOR obfuscation (section

  • Office binary document RC4 encryption (section

  • Office binary document RC4 CryptoAPI encryption<8> (section

If FibBase.fEncrypted and FibBase.fObfuscation are both 1, the file is obfuscated by using XOR obfuscation (section as specified in section

If FibBase.fEncrypted is 1 and FibBase.fObfuscation is 0, the file is encrypted by using either Office Binary Document RC4 Encryption (section or Office Binary Document RC4 CryptoAPI Encryption (section, with the EncryptionHeader stored in the first FibBase.lKey bytes of the Table stream. The EncryptionHeader.EncryptionVersionInfo specifies which encryption mechanism was used to encrypt the file.

See Security Considerations for information about security concerns relating to file obfuscation and encryption for this file format.