<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;">On Sep 27, 2014, at 2:55 PM, Tony Arcieri <<a href="mailto:bascule@gmail.com">bascule@gmail.com</a>> wrote:<div><br><div><blockquote type="cite"><div dir="ltr"><div class="gmail_extra">Do you really think that the NSA cant pull off the 51% attack on Namecoin?</div></div></blockquote><div><div dir="ltr"><div class="gmail_extra"><br></div><div class="gmail_extra">Ah, now you're talking sense. :-)</div><div class="gmail_extra"><br></div><div class="gmail_extra">I really don't think that, and it's discussed in the blog post:</div><div class="gmail_extra"><br></div><div class="gmail_extra"><a href="https://blog.okturtles.com/2014/09/the-trouble-with-certificate-transparency/">https://blog.okturtles.com/2014/09/the-trouble-with-certificate-transparency/</a></div><div class="gmail_extra"><br></div><div class="gmail_extra">51% attack is a legitimate problem that can result in censorship of the network.</div><div class="gmail_extra"><br></div><div class="gmail_extra">Note that it doesn't allow the NSA to lie about a certificate though. In many ways, 51% attack is just another form of censorship. They would probably prefer to just censor the connection.</div><div class="gmail_extra"><br></div><div class="gmail_extra">Details of what 51% allows and does not allow are copied here from the bitcoin wiki:</div></div></div></div></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;"><div><div><div><div dir="ltr"><div class="gmail_extra"><p>An attacker that controls more than 50% of the network's computing
power can, for the time that he is in control, exclude and modify the
ordering of transactions. This allows him to:
</p></div></div></div></div></div></blockquote><div><div><div dir="ltr"><div class="gmail_extra">
<ul>
<ul><li> Reverse transactions that he sends while he's in control. This has the potential to <a href="https://en.bitcoin.it/wiki/Double-spending#51.25_attack" title="Double-spending">double-spend transactions</a> that previously had already been seen in the block chain.
</li><li> Prevent some or all transactions from gaining any confirmations
</li><li> Prevent some or all other miners from mining any valid blocks
</li></ul>
</ul></div></div></div></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;"><div><div><div dir="ltr"><div class="gmail_extra"><p>The attacker <i>can't</i>:
</p></div></div></div></div></blockquote><div><div><div dir="ltr"><div class="gmail_extra">
<ul>
<ul><li> Reverse other people's transactions
</li><li> Prevent transactions from being sent at all (they'll show as 0/unconfirmed)
</li><li> Change the number of coins generated per block
</li><li> Create coins out of thin air
</li><li> Send coins that never belonged to him
</li></ul>
</ul><div>From: <a href="https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_computing_power">https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_computing_power</a></div><div><br></div><div>Kind regards,</div><div>Greg Slepak</div></div></div></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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