A method for protecting software is provided, where source code for the software has a first directive marking an encryption beginning point and a second directive marking an encryption end point. The method contains the steps of: processing the source code to identify a block of code between the first and second directives; compiling the source code to produce a binary file; generating a valid key and a random string; encrypting the random string with the key to obtain a first encrypted value; encrypting a portion of the binary file corresponding to the block of code with the valid key to obtain a second encrypted value; and replacing the portion of the binary file corresponding to the block of code with the second encrypted value and code that can decrypt the second encrypted value during execution of the software.