<p dir="ltr">Because it's trivial to create collisions! You can choose exactly what output you want. That's why XOR is a very bad digest scheme.</p>
<p dir="ltr">- Sent from my phone</p>
<div class="gmail_quote">Den 4 feb 2014 14:20 skrev "Peter Todd" <<a href="mailto:pete@petertodd.org">pete@petertodd.org</a>>:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
On Tue, Feb 04, 2014 at 02:13:12PM +0100, Mike Hearn wrote:<br>
> Hah, good point. If nobody completes the homework, I'll post a fixed<br>
> version tomorrow :)<br>
<br>
Heh, here's another 25mBTC while we're at it:<br>
<br>
<a href="https://github.com/opentimestamps/opentimestamps-client/commit/288f3c17626974de7eaef4f1c9b5cd93eecf40f6" target="_blank">https://github.com/opentimestamps/opentimestamps-client/commit/288f3c17626974de7eaef4f1c9b5cd93eecf40f6</a><br>
<br>
Why is that a bad idea?<br>
<br>
Bonus question: What was I smoking? (hint: where do I live?)<br>
<br>
> On Tue, Feb 4, 2014 at 2:03 PM, Peter Todd <<a href="mailto:pete@petertodd.org">pete@petertodd.org</a>> wrote:<br>
><br>
> > On Tue, Feb 04, 2014 at 01:01:12PM +0100, Mike Hearn wrote:<br>
> > > Hello,<br>
> > ><br>
> > > I'm pleased to announce the release of bitcoinj 0.11, a library for<br>
> > writing Bitcoin applications that run on the JVM. BitcoinJ is widely used<br>
> > across the Bitcoin community; some users include Bitcoin Wallet for<br>
> > Android, MultiBit, Hive, <a href="http://blockchain.info" target="_blank">blockchain.info</a>, the <a href="http://biteasy.com" target="_blank">biteasy.com</a> block explorer<br>
> > (written in Lisp!), Circle, Neo/Bee (Cypriot payment network), <a href="http://bitpos.me" target="_blank">bitpos.me</a>,<br>
> > Bitcoin Touch, BlueMatt's relay network and DNS crawler, academic advanced<br>
> > contracts research and more.<br>
> > ><br>
> > > The release-0.11 git tag is signed by Andreas Schildbach's GPG key. The<br>
> > commit hash is 410d4547a7dd. This paragraph is signed by the same Bitcoin<br>
> > key as with previous releases (check their release announcements to<br>
> > establish continuity). Additionally, this email is signed using DKIM and<br>
> > for the first time, a key that was ID verified by the Swiss government.<br>
> > ><br>
> > > Key: 16vSNFP5Acsa6RBbjEA7QYCCRDRGXRFH4m<br>
> > > Signature for last paragraph:<br>
> > H3DvWBqFHPxKW/cdYUdZ6OHjbq6ZtC5PHK4ebpeiE+FqTHyRLJ58BItbC0R2vo77h+DthpQigdEZ0V8ivSM7VIg=<br>
> ><br>
> > The above makes for a great homework problem for budding cryptographers:<br>
> > Why did the three forms of signature, DKIM, long-lived bitcoin address,<br>
> > and Official Swiss Government Identity fail to let you actually verify<br>
> > you have the right code? (but make for great security theater)<br>
> ><br>
> > Bonus question: Who has the smallest work-factor for such an attack?<br>
> ><br>
> > Two rewards of 25mBTC for correct responses to each question from a<br>
> > crypto newbie.<br>
> ><br>
> > > Thanks to Mike Belshe, the wallet can now send to P2SH addresses.<br>
> ><br>
> > Thanks<br>
> ><br>
> > > Generated signatures now use canonical S values. This will aid a future<br>
> > hard-forking rule change which bans malleable signatures.<br>
> ><br>
> > Soft-forking rule change.<br>
> ><br>
> > --<br>
> > 'peter'[:-1]@<a href="http://petertodd.org" target="_blank">petertodd.org</a><br>
> > 000000000000000075829f6169c79d7d5aaa20bfa8da6e9edb2393c4f8662ba0<br>
> ><br>
<br>
--<br>
'peter'[:-1]@<a href="http://petertodd.org" target="_blank">petertodd.org</a><br>
000000000000000075829f6169c79d7d5aaa20bfa8da6e9edb2393c4f8662ba0<br>
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