ROT13
Apply "ROT13" Transformation to a File

ROT13 is a C program which reads a file and makes a copy in which all characters have been "rotated" by 13 positions, and all digits have been "rotated" by 5 positions.

Applying ROT13 to the transformed file returns the original. Thus, ROT13 can be used as a very simply method of encoding and decoding text files. Only an idiot would be fooled by this encoding, but nonetheless the encoding serves a number of useful purposes. And often, it's only idiots you have to fool, after all.

Usage:

rot13 file1.txt

• file1.txt is the input file to be encoded.

Licensing:

The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.

Languages:

ROT13 is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.

Related Data and Programs:

ATBASH, a C library which applies the Atbash substitution cipher to a string of text.

CAESAR, a C library which can apply a Caesar Shift Cipher to a string of text.

CHRPAK, a C library which works with characters and strings.

FILUM, a C library which performs various operations on files.

PIG_LATIN, a C program which makes a copy of a file, translating the text into Pig Latin.

UUDECODE, a C program which reads a UU encoded text file and translates it back to its original form.

UUENCODE, a C program which translates a file (possibly in binary format) to the UU encoding.

Source Code:

• rot13.c, the source code;

Examples and Tests:

• gettysburg.txt, Lincoln's Gettysburg Address.
• trgglfohet.gkg, the file, encoded by ROT13.

List of Routines:

• MAIN is the main program for ROT13.
• CH_TO_ROT13 converts a character to its ROT13 equivalent.
• HANDLE makes a copy of a file after applying ROT13 to it.
• S_TO_ROT13 "rotates" the alphabetical characters in a string by 13 positions.
• TIMESTAMP prints the current YMDHMS date as a time stamp.

You can go up one level to the C source codes.