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List:       cryptography
Subject:    Re: [Cryptography] RC4 thought experiment
From:       Tom Mitchell <mitch () niftyegg ! com>
Date:       2015-06-11 18:53:24
Message-ID: CAAMy4URsOxgxEz_UYeEUwDsVAaqu7VmZUnUpymxd0OFb0XKrXw () mail ! gmail ! com
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On Sun, Jun 7, 2015 at 7:57 PM, Ryan Carboni <ryacko@gmail.com> wrote:

> This is purely a thought experiment, but the only secure communications
> method is probably RTTY over phone lines, with encryption. 7-bit ASCII. And
> each RC4 keystream byte is truncated to 7-bits. How would this influence
> the biases?
>

*RTTY* (radio teletype) has a baud rate of about 45+change and is based on
a 5-bit Baudot code.
It would take a while to grind through many modern large key size hand
shakes.

With modern cell phones old acoustic modem signal rates are clamped.  Given
the growing
dominance of cell phones some work might add a side or back channel for
making voice and data
over IP interesting.   As a bootstrap start sharing the local IP address
and TCP version
and then transition from audio to a point to point TCP/IP link and port
number.  Or a VPN server... or....




> --
  T o m    M i t c h e l l

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<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Jun \
7, 2015 at 7:57 PM, Ryan Carboni <span dir="ltr">&lt;<a \
href="mailto:ryacko@gmail.com" target="_blank">ryacko@gmail.com</a>&gt;</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"><div \
dir="ltr">This is purely a thought experiment, but the only secure communications \
method is probably RTTY over phone lines, with encryption. 7-bit ASCII. And each RC4 \
keystream byte is truncated to 7-bits. How would this influence the biases?  \
</div></blockquote><div><br></div><div><strong \
style="margin:0px;padding:0px;border:0px;outline:0px;font-size:14.0018014907837px;vert \
ical-align:baseline;color:rgb(34,68,102);font-family:Arial,sans-serif;line-height:21.0 \
027027130127px;background-image:initial;background-repeat:initial">RTTY</strong><span \
style="color:rgb(34,68,102);font-family:Arial,sans-serif;font-size:14.0018014907837px;line-height:21.0027027130127px"> \
(radio teletype) has a baud rate of about 45+change and is based on a  </span><span \
style="color:rgb(34,68,102);font-family:Arial,sans-serif;font-size:14.0018014907837px;line-height:21.0027027130127px">5-bit \
Baudot code.</span><br></div><div><span \
style="color:rgb(34,68,102);font-family:Arial,sans-serif;font-size:14.0018014907837px;line-height:21.0027027130127px">It \
would take a while to grind through many modern large key size hand \
shakes.</span></div><div><span \
style="color:rgb(34,68,102);font-family:Arial,sans-serif;font-size:14.0018014907837px;line-height:21.0027027130127px"><br></span></div><div><font \
color="#224466" face="Arial, sans-serif"><span \
style="font-size:14.0018014907837px;line-height:21.0027027130127px">With modern cell \
phones old  acoustic  modem signal rates are clamped.   Given the \
growing</span></font></div><div><font color="#224466" face="Arial, sans-serif"><span \
style="font-size:14.0018014907837px;line-height:21.0027027130127px">dominance of cell \
phones some work might add a side or back channel for making voice and \
data</span></font></div><div><font color="#224466" face="Arial, sans-serif"><span \
style="font-size:14.0018014907837px;line-height:21.0027027130127px">over IP \
interesting.    As a bootstrap start sharing the local IP address and TCP \
version</span></font></div><div><font color="#224466" face="Arial, sans-serif"><span \
style="font-size:14.0018014907837px;line-height:21.0027027130127px">and then \
transition from audio to a point to point TCP/IP link and port number.   Or a VPN \
server... or....</span></font></div><div><span \
style="color:rgb(34,68,102);font-family:Arial,sans-serif;font-size:14.0018014907837px;line-height:21.0027027130127px"><br></span></div><div><span \
style="color:rgb(34,68,102);font-family:Arial,sans-serif;font-size:14.0018014907837px;line-height:21.0027027130127px"><br></span></div><div><span \
style="color:rgb(34,68,102);font-family:Arial,sans-serif;font-size:14.0018014907837px;line-height:21.0027027130127px"><br></span></div><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"><br></blockquote></div>-- \
<br><div class="gmail_signature"><div dir="ltr">   T o m      M i t c h e l \
l</div></div> </div></div>


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