113 lines
4.6 KiB
HTML
113 lines
4.6 KiB
HTML
<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta content="text/html; charset=UTF-8" http-equiv="content-type">
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<style>
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body {
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max-width: 30em;
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margin-left: 2em;
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}
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p.center {text-align:center;}
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</style>
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<link rel="shortcut icon" href="../rho.ico">
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<title>Squaring Zooko’s triangle</title>
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</head>
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<body>
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<p><a href="./index.html"> To Home page</a> </p>
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<h1>Squaring Zooko’s triangle</h1>
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<p>
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Need a system for handing one’s keys around that protects end users from the horrifying sight of actual keys or actual strong hashes of keys.</p>
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<p>
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But at the same time the system has to not say, "I can’t deliver your message to that person because an invisible gnotzaframmit that I won’t describe to you seems to be unavailable to me in the flabogrommit."</p>
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<p>It seems like the clever bit of CT is the insight that some actions, like
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a CA signing a cert, are intended to be public, and so should be forced
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(via clever crypto) to take place in public. This makes me wonder what
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other crypto actions should also take place in public, in a way that
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doesn’t permit hiding them from the world. </p>
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<p>Revocation </p>
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<p>Software releases </p>
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<p>Mapping of email address to public key </p>
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<p>Delegation of DNSSEC keys </p>
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<p> </p>
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<p>Of course, globally visible events need to take place at a globally
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visible time. The most widely available time is GPS time (which is 19
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seconds off the commonly used time), and which is available from the
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seldom connected pps line.</p>
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<p>At present, unfortunately, anyone who wants gps time has to do his own
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soldering and hack his own software. There is a pre soldered device
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available, but it is hard to get. </p>
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<p> </p>
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<p> </p>
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<p>
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Imagine skype as originally designed, (central authority maps public and
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private keys to user names) plus a key continuity feature, plus the seldom
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used option of doing a zero knowledge shared passphrase to detect man in
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the middle. </p>
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<p>
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The possibility that the zero knowledge check could be used would deter
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powerful adversaries, even if seldom used in practice. The more powerful,
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the greater the deterrent effect. </p>
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<p>
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It is not totally end to end, central authority can listen in, but the
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check would limit the amount of listening. </p>
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<p>
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It can be made completely end to end for strong passwords. Assume login is
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by zero knowledge password protocol, which means that the central
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authority does not know the end user’s password, for strong
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passwords. </p>
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<p>
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The secret key is generated from the strong secret supplied by central
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authority, plus the password. </p>
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<p>
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When you change your password, you generate a certificate mapping your new
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public key to your old public key, which certificate makes other people’s
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key continuity check happy. </p>
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<p>
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If key continuity fails, people get a warning, but they don’t have to
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click it away, for that just trains people to click it away. They can just
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continue right on and not pay attention to it. </p>
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<p>
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Or they could use the zero knowledge shared passphrase procedure to detect
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man in the middle. </p>
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<p>
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So, if non paranoid, and using easy passwords, works like skype used to
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work. No interception except by central authority, and central authority
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cannot intercept everyone, or even large numbers of people. </p>
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<p>
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If paranoid and using strong passwords, provides OTR like end to end
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capability. </p>
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<p><br/>
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</p>
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<p><br/>
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</p>
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<p>Key management is an unsolved problem. In my biased opinion the
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best<br/>
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solution was my Crypto Kong, which received limited takeup.<br/>
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<br/>
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So, in conclusion, don’t make people manage keys, though that should be an
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option for the seriously paranoid.<br/>
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<br/>
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Instead, autogenerate the keys with zero knowledge passphrase logon.<br/>
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<br/>
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If he uses a password weak enough to fall to an offline dictionary attack,
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this is equivalent to the old skype system, where central authority
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manages his keys and he has password logon. If he uses a stronger
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password, equivalent to a salted strong passphrase system.</p>
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<p> </p>
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<p> </p>
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<p> </p>
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<p> </p>
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<p> </p>
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<p> </p>
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<p style="background-color : #ccffcc; font-size:80%">These documents are
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licensed under the <a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/">Creative
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Commons
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Attribution-Share Alike 3.0 License</a></p>
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</body>
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</html>
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