ROT13 is a FORTRAN90 library which is given a string and applies the ROT13 cipher to characters and the ROT5 cipher to digits.
For example, we have:
Input: Output: abcdefghijklmnopqrstuvwxyz nopqrstuvwxyzabcdefghijklm Cher Pure James Thurston Howell Wnzrf Guhefgba Ubjryy 0123456789 56789012345
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
ROT13 is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version and a Python version.
CAESAR, a FORTRAN90 library which can apply a Caesar Shift Cipher to a string of text.
CHRPAK, a FORTRAN90 library which works with characters and strings.
FILUM, a FORTRAN90 library which can work with information in text files.
You can go up one level to the FORTRAN90 source codes.