Patent ID: 8484232

Claim:
A method for checking for the presence of control statements in a data value, comprising: providing at least one first data value ( 8 ) from a trustworthy source ( 3 ); receiving at least one second data value ( 9 ) from an untrustworthy source ( 4 ) and marking the second data value ( 9 ) as untrustworthy; performing a computation on the first data value ( 8 ) and second data value ( 9 ) resulting in a third data value ( 10 ) and marking parts ( 11 ) of the third data value ( 10 ) which are derived from the second data value ( 9 ) as untrustworthy, said computation including replacing a portion of the first data value ( 8 ) with the second data value ( 9 ); and checking the parts ( 11 ) of the third data value ( 10 ) marked as untrustworthy for a presence of control statements, wherein if no control statement is detected, then providing said third data value for further processing, and wherein if a control statement is identified, then providing said third data for further processing only after removing said control statement from said third data value.