To hide a file[keylogger,virus,any file] inside a jpeg image file,do the following:
1]You will need two files-The file in which you have your keylogger and one jpeg image[It can be of any size or dimensions].[If you want to hide multiple files in one jpeg image, just zip them into one file]
2]Copy the above two files to the C:Drive
3]Open the command prompt window[Run>cmd].
4]Move to the c: root by typing cd/
5]Type the Following COMMAND:
copy /b IMAGE FILE NAME.jpg + FILE NAME.exe NEW IMAGE NAME.jpg
6]To recover the original exe file, just rename NEW IMAGE FILE.jpg to filename.exe.