The reason it is generally considered bad form is you have no control over the data:
  1. Consider a replay attack. Someone gets the encrypted information stores it for a while and sends it back.

    I have other measures to counter a replay attack -- the data can only be entered into the database once. Replays fail if the record already exists in the database.

  2. Consider a crack of the cypher. Someone determines the plaintext, modifies it and sends it back (not to mention your entire application is now exposed).

    Interesting point -- I'll amend my approach to modify the data before encryption, then reverse that process when it comes out the other side.

  3. Consider a corruption. Someone arbitrarily changes some bytes and sends it back. It may decrypt and crash (or worse!) your application.

    I'll have to live with that .. it's been a while since I saw a web page corrupted.

--t. alex

"Here's the chocolates, and here's the flowers. Now how 'bout it, widder hen, will ya marry me?" --Foghorn Leghorn

In reply to Re: Re: Length of Crypt::CBC result by talexb
in thread Length of Crypt::CBC result by talexb

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.