2.3.7.1 Binary Document Password Verifier Derivation Method 1

The CreatePasswordVerifier_Method1 procedure specifies how a 16-bit password verifier is obtained from an ASCII password string. The password verifier is used in XOR obfuscation as well as for document write protection.

The CreatePasswordVerifier_Method1 procedure takes the following parameter:

• Password: An ASCII string that specifies the password to be used when generating the verifier.

   FUNCTION CreatePasswordVerifier_Method1
       PARAMETERS Password
       RETURNS 16-bit unsigned integer
    
       DECLARE Verifier AS 16-bit unsigned integer
       DECLARE PasswordArray AS array of 8-bit unsigned integers
    
       SET Verifier TO 0x0000
       SET PasswordArray TO (empty array of bytes)
       SET PasswordArray[0] TO Password.Length
       APPEND Password TO PasswordArray 
    
       FOR EACH PasswordByte IN PasswordArray IN REVERSE ORDER
          IF (Verifier BITWISE AND 0x4000) is 0x0000
             SET Intermediate1 TO 0
          ELSE
             SET Intermediate1 TO 1
          ENDIF
    
          SET Intermediate2 TO Verifier MULTIPLED BY 2
          SET most significant bit of Intermediate2 TO 0
    
          SET Intermediate3 TO Intermediate1 BITWISE OR Intermediate2
          SET Verifier TO Intermediate3 BITWISE XOR PasswordByte
       ENDFOR
    
       RETURN Verifier BITWISE XOR 0xCE4B
   END FUNCTION
  

For more information, see section 4.