After encryption, an exe file becomes non-executable

Question

After writing a basic LFSR-based stream cipher encryption module in C, I tried it on usual text files, and then on a .exe file in Windows. However, after decrypting it back the file is not running, giving some error about being a 16-bit. Evidently some error in decrypting. Or are files made so that if I tamper with their binary code they become corrupted? I'm checking my program on text-files in the hope of locating any error on my part. However, the question is had anyone tried running your own encryption programs on an executable file? Is their any obvious answer to this? JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

There is nothing special about executables. They are obviously binary files and thus contain 00 bytes and bytes >127. As long as your algorithm is binary safe, it should work. Compare the original file and the decrypted file using a hex-editor. To see how they differ. The error you get means that you didn't decrypt the executable header correctly, so the decryption mistake must already affect the first few bytes of your file.