[Bitcoin-development] Electrum security model concerns

[Gregory Maxwell]

On Sat, Oct 6, 2012 at 12:37 PM, Gregory Maxwell <gmaxwell at gmail.com> wrote:
> I'm concerned about how the particular security model of electrum is
> being described; or rather— not being described.

Just to close the loop on this: I finally got in touch with Thomas on
IRC and walked over the security issues I brought up here, plus a
number of other ones.

He took the concerns seriously and rapidly redesigned big swaths of
electrum to eliminate the issues structurally.  Electrum no longer a
classical thin client it is now a slightly watered down
simplified-payment-validation node with generally the same security
properties as other SPV nodes. Its network behavior leaves it somewhat
more vulnerable to isolation and compromise by a high hash power
attacker, because it does not (yet) make an effort to make sure it's
really on the longest chain. It is also more vulnerable to transaction
hiding (a DOS attack) for similar reasons.  But this is still a
massive improvement.  The UI was also changed and the confirmation
status of payments is no longer hidden.

There are still things to improve— both in the client and the security
communication to users. But I wanted to leave a note that it's come a
long way and that I now feel confident that any remaining issues will
be resolved.