genotp.py

#!/usr/bin/env python
# file: genotp.py
# vim:fileencoding=utf-8:ft=python
#
# Copyright © 2014-2018 R.F. Smith <rsmith@xs4all.nl>.
# SPDX-License-Identifier: MIT
# Created: 2014-03-08T14:04:00+01:00
# Last modified: 2018-08-02T00:51:46+0200
"""
Generate an old-fashioned one-time pad.

The format of the one-time pad is:
65 lines of 12 groups of 5 random capital letters.
"""

from secrets import choice

_CAPS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"


def main():
    """Entry point."""
    r = rndcaps(10)
    print(f"+++++ {r} +++++")
    print(otp())


def otp(n=65):
    """
    Return a one-time pad.

    Arguments:
        n: number of lines in the key

    Returns:
        n lines of 12 groups of 5 random capital letters.
    """
    lines = []
    for num in range(1, n + 1):
        i = [f"{num:02d} "]
        i += [rndcaps(5) for j in range(0, 12)]
        lines.append(" ".join(i))
    return "\n".join(lines)


def rndcaps(n):
    """
    Generates a string of random capital letters.

    Arguments:
        n: Length of the output string.

    Returns:
        A string of n random capital letters.
    """
    return "".join([choice(_CAPS) for c in range(n)])


if __name__ == "__main__":
    main()