I'd take that bet for every cent I have - the modulo solution changes each character to another random character. Only the length of the message persists in additional runs. In the xor, some information survives each run.

update: And note in your wager, to win two things have to happen:

1) xor breaks if process repeated with small changes and
2) same for modulo.

Even if I am wrong about 1) and I may well try to prove, I could still win the bet on 2) alone. I can't prove 2) is unbreakable beyond proving that each run is as good as a fixed number of random numbers. But 1) I may well have a go at sometime during the next few years (other projects taking priority for now).

More update: your intuition is clearly a disaster. You are saying that a version which passes NO information from one run to the next is only secure if one that passes some information is secure. That's like saying a house can only be secured by locking all the doors if it is also secure when a door is left open.

-- Enough is enough -- setting tobyink to ignore.


In reply to Re^5: crypto with core modules only by TheloniusMonk
in thread crypto with core modules only by morgon

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.