hi all
i want write a simple file encrypting like this :
http://board.flatassembler.net/topic.php?t=8951
but WITHOUT ANY MACRO , completely in assembly .
but i don't know how . please help me .
thanks in advance .

A macro isn't a function.
If you dont know anything about PE format, it would be hard to write such stuff.

Map the file to memory/read it to memory, verify its a PE file, optional but useful. Get the offset to the code/text/data/whatever section you wish to encrypt from the PE header, encrypt it. As for the actual code cave for the decryption, I am not sure on how to do that...

you can add the size of your decryptor to the last section and copy there or create a new section and copy the decryptor to it. You also need to modify the EntryPoint in PE header to point to your decryptor (in last section or in the new section). At finish you must "jump" to the original entrypoint so the original program will execute.

do not forget to add the Writing attribute to the section you want to encrypt especially the code section.