<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">As I understand it, quantum computers effectively halve the keyspace, so perhaps "suck" is too strong a term, but it isn't completely catastrophic for symmetric encryption the same way it is with RSA/ECC-like pubkey systems. </div></div></div></blockquote><div><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><br></div><div class="gmail_quote">That's not my understanding.</div><div class="gmail_quote"><br></div><div class="gmail_quote">The document I'm looking at [1] is quite damning and indicates QM systems break traditional symmetric ciphers like DES and AES in no time at all using "20 questions" algorithm:</div><div class="gmail_quote"><br></div><div class="gmail_quote">
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<div class="column"><p></p></div></div></div></div></div></div></div></div><blockquote type="cite"><div><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote"><div class="page" title="Page 3"><div class="section" style="background-color: rgb(255, 255, 255); position: static; z-index: auto;"><div class="layoutArea"><div class="column"><p><span style="font-size: 10.000000pt; font-family: 'Verdana'">If we guess that each iteration will take 1 millisecond, then the total time for a
known plaintext attack on DES is going to be 56 milliseconds.
</span></p><p><span style="font-size: 10.000000pt; font-family: 'Verdana'">Cipher systems like AES-256 can also be broken is less than a second.<br>
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</div></div></div></div></div></blockquote><div><br class="webkit-block-placeholder"></div><div>- Greg</div><div><br></div><div>[1] Quantum Computers for Code Breaking, Dave D' Rave, 2600 Magazine</div><div>
<br class="Apple-interchange-newline"><span style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; display: inline !important; float: none;">--</span><br style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><span style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; display: inline !important; float: none;">Please do not email me anything that you are not comfortable also sharing</span><span style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; display: inline !important; float: none;"> with the NSA.</span>
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<br><div><div>On Jan 25, 2015, at 11:06 AM, Tony Arcieri <<a href="mailto:bascule@gmail.com">bascule@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Sun, Jan 25, 2015 at 11:04 AM, Tao Effect <span dir="ltr"><<a href="mailto:contact@taoeffect.com" target="_blank" onclick="window.open('https://mail.google.com/mail/?view=cm&tf=1&to=contact@taoeffect.com&cc=&bcc=&su=&body=','_blank');return false;">contact@taoeffect.com</a>></span> wrote:<br><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; position: static; z-index: auto;"><div style="word-wrap:break-word"><span class=""><i>"More good news: quantum computers suck at breaking symmetric encryption"</i><br></span><div><div><br></div><div>Do you have a citation for that? It conflicts with what I've heard from others.</div></div></div></blockquote><div><br></div><div>As I understand it, quantum computers effectively halve the keyspace, so perhaps "suck" is too strong a term, but it isn't completely catastrophic for symmetric encryption the same way it is with RSA/ECC-like pubkey systems. </div></div><div><br></div>-- <br><div class="gmail_signature">Tony Arcieri<br></div>
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