Implement a [[wp:One-time pad|One-time pad]], for encrypting and decrypting messages.<br>
To keep it simple, we will be using letters only.

;Sub-Tasks:
* '''Generate''' the data for a One-time pad (user needs to specify a filename and length)
: The important part is to get "true random" numbers, e.g. from /dev/random
* '''encryption / decryption''' ( basically the same operation, much like [[Rot-13]] )
: For this step, much of [[Vigenère cipher]] could be reused,<br>with the key to be read from the file containing the One-time pad.
* optional: '''management''' of One-time pads: list, mark as used, delete, etc.
: Somehow, the users needs to keep track which pad to use for which partner.

To support the management of pad-files:
* Such files have a file-extension ".1tp"
* Lines starting with "#" may contain arbitary meta-data (i.e. comments)
* Lines starting with "-" count as "used"
* Whitespace within the otp-data is ignored
<!-- 
maybe support for 1tp-files on readonly-media,
i.e. an indexfile that stores which parts have been used
-->


For example, here is the data from [http://upload.wikimedia.org/wikipedia/commons/6/60/One-time_pad.svg Wikipedia]:
<pre>
# Example data - Wikipedia - 2014-11-13
-ZDXWWW EJKAWO FECIFE WSNZIP PXPKIY URMZHI JZTLBC YLGDYJ 
-HTSVTV RRYYEG EXNCGA GGQVRF FHZCIB EWLGGR BZXQDQ DGGIAK 
 YHJYEQ TDLCQT HZBSIZ IRZDYS RBYJFZ AIRCWI UCVXTW YKPQMK 
 CKHVEX VXYVCS WOGAAZ OUVVON GCNEVR LMBLYB SBDCDC PCGVJX 
 QXAUIP PXZQIJ JIUWYH COVWMJ UZOJHL DWHPER UBSRUJ HGAAPR 
 CRWVHI FRNTQW AJVWRT ACAKRD OZKIIB VIQGBK IJCWHF GTTSSE 
 EXFIPJ KICASQ IOUQTP ZSGXGH YTYCTI BAZSTN JKMFXI RERYWE 
</pre>
<br><br>
;See also
* [https://breakingcode.wordpress.com/2010/02/17/one-time-pad-encryption-in-python/ one time pad encryption in Python]
* [https://github.com/snapfractalpop/1tp snapfractalpop] -  One-Time-Pad Command-Line-Utility (C).
* [http://search.cpan.org/~sifukurt/Crypt-OTP-2.00/OTP.pm Crypt-OTP-2.00] on CPAN (Perl)
<br><br>