Re: SSHv1's exponent is always 35

yawnmoth <terra1024@xxxxxxxxx> wrote:
Every time I connect to an SSHv1 server and get the public key modulo /
exponent, the exponent is always 35. Should it be?

It's not _guaranteed_ to be. One particular key generator always
chooses the exponent to be 35, and that particular key generator is
more widely used than others, so you will see an overwhelming
majority of exponents being 35. But it's permitted for someone to
write a key generator which uses a different (or even - *gasp* - a
randomly chosen) exponent, and therefore clients and servers are
required to be able to handle this case correctly in case it comes
up.

(PuTTY's key generator consistently uses 37, as it happens, because
my generation algorithm found it more convenient to have the
exponent be prime. However, PuTTY's key generator isn't often used
to generate _server_ public keys, although it should work fine if
someone really wanted to.)
--
Simon Tatham "A defensive weapon is one with my finger on the
<anakin@xxxxxxxxx> trigger. An offensive weapon is one with yours."
.