<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div><div dir="ltr" class=""><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On 02/06/2016 06:29 AM, Henry Baker wrote:<br class=""></span></blockquote></div></div></div></div><div><div class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><span class="">> Consequently, you are cordially invited to submit a proposal for a block cipher that :<br class="">> Works on block sizes of 1 kbytes, 4 kbytes, 16 kbytes and 64 kbytes. Bonus points for ciphers that work on an arbitrary block size.</span></blockquote></div><div class=""><span class=""><br class=""></span></div><div class="">Creating a new large block cipher can be accomplished as a mode to a short block cipher. All of these work on multiples of the underlying block cipher. </div><ul class=""><li class="">Naor and Reingold, A pseudo-random encryption mode. <a href="http://www.wisdom.weizmann.ac.il/" class="">http://www.wisdom.weizmann.ac.il/</a>∼naor/ </li><li class="">Luby and Rackoff, How to construct pseudorandom permutations from pseudorandom functions. SIAM J. of Computation </li><li class="">Halevi and Rogaway, A Parallelizable Enciphering Mode, <a href="http://web.cs.ucdavis.edu/~rogaway/papers/eme.pdf" class="">http://web.cs.ucdavis.edu/~rogaway/papers/eme.pdf</a></li></ul><div class="">Ciphertext Stealing, they can work with Halevi and Rogaway to form an arbitrary block size. </div><div class=""><br class=""></div><div class="">> Use a 64 kbyte key.<br class=""></div><div class=""><br class=""></div><div class=""><div><div class="">Unless you want to go to all the way to a OTP, it is better to work on an extremely good source of entropy than a large key >> 256 bits. Without good entropy, even long keys (> 1000 bits) you still have a problem. </div><div class=""><br class=""></div><div class=""><ul class="MailOutline"><li class="">Lenstra et.al. Ron was wrong, Whit is right, <a href="https://eprint.iacr.org/2012/064.pdf" class="">https://eprint.iacr.org/2012/064.pdf</a></li></ul><div class=""><div class=""><br class=""></div><div class="">> Fits In Head</div></div></div><div class=""><br class=""></div><div class="">Even the OTP does not meet the “Fits in Head” criteria. The idea of Shannon’s famous paper can fit in a soundbite, the the facts are 55 hard pages long. </div><div class=""><br class=""></div><div class=""><ul class="MailOutline"><li class="">Shannon, <a href="https://en.wikipedia.org/wiki/A_Mathematical_Theory_of_Communication" title="A Mathematical Theory of Communication" style="text-decoration: none; color: rgb(11, 0, 128); background-image: none; font-family: sans-serif; font-size: 13px;" class="">A Mathematical Theory of Communication</a><font size="2" class=""><span style="background-color: rgb(255, 255, 255);" class="">. </span></font><font color="#252525" face="sans-serif" size="2" class=""><a href="http://worrydream.com/refs/Shannon%20-%20A%20Mathematical%20Theory%20of%20Communication.pdf" class="">http://worrydream.com/refs/Shannon%20-%20A%20Mathematical%20Theory%20of%20Communication.pdf</a></font></li></ul><div class=""><br class=""></div></div><div class=""><br class=""></div><div class=""><div dir="ltr" class=""><div class="gmail_extra"></div></div></div></div></div></div></body></html>