[Music]
hi thank you MOS for the presentation
and thank you everybody for coming my
name is ignazi Ramos I work at polygon
at the protocol team and today I will be
presenting what the frog is the
pessimistic proof but before going
straight to the pessimistic proof let me
give you a bit of
context and nowaday one of the problems
of of blockchain not being mainstream in
my opinion is the the fragmentation
there are a lot of good projects and
they have to deploy in all the chains
but the worst thing is that for the user
experience this is like very very bad
because they may want to use for one
reason or another or or or another more
than one chain Two Chains whatever
number of
chains so if they want to move assets
from one chain to another one sometimes
there are delays some sometimes it's
difficult to track hike fees they have
to wait a lot this is why um from
polygon we
propose the aggregation
layer the agregation layer connects
Sovereign chains together unifying
liquidity users and state but with the
feel of a single chain a multi-chain web
that is better for the user experience
better for Network effects and better
for security we think for example like
internet well where everything is built
at the top top of the same protocol the
TCP IP in the aggregation layer we will
be aggregating chain in a unified bridge
and they not have to be only evbm chain
compatibles they can only be like what
we call Sovereign chains for example a
Solana whatever chain that they maintain
like an state of their
balances but with this system there is a
problem what happen if one of these
change is compromised what happen if one
of these chains has a back that the
bridge gets brain what will happen is
that the other chains will be affected
because of the insecurity of one of the
other chains this is where we
introduce the pessimistic proof the
pessimistic proof has this name because
it pessimistically thinks that any of
the chains that are added in the
aggregation layer can be
vulnerable so it tries to secure this
how does it do it the solution is to
architect the aggregation layer in a way
that assumes that every prer can be un
sound the pessimistic proof guarantees
that even if a PR for a particular chain
is UN sound that Pro cannot drain more
funds than are currently deposited on
that chain in this way a sound issue
cannot infect the rest of the
ecosystem so this means that every time
a chain wants to submit their Bridges to
be Consolidated he will has to attach a
proof proving that he has enough balance
to execute those
bridges the proving system that will um
handle all of these the proof generation
and the verification can be any of the
advaned like General BMS like for
example dis for example R zero or
sp1 so let's go a bit deeper on the
pessimistic proof now we will get a bit
more Tech but it will be anyway very
high yes very high level at least this
is a aligning talk so it will be it will
be
painless so we handle this the proof
generation with the3 we have the local
balance Tre the local Exit 3 and the
nullifier threee the local balance Tre
is the one that handles the balance of
each one of the tokens in the network
each one of the Le has the following
information the origin network of the
token the token address and the balance
the origin Network and the token address
completely define a token so this
balance is the one that handles all the
balances of the tokens in the CH in in
one in each one of the chains another
one is the local Exit 3 the local Exit 3
grow sequentially every time a bridge is
created so in each one of the in each
one of the leaves he has the information
of a bridge a even yes and the third one
is the nullifier tree the nullifier tree
basically it's used for the um
aggregation layer um to avoid the double
spending I will explain it
later and finally the step steps for
computing this proof are this four well
here it's a a very summarize oface first
of all you apply the Bridge exit to all
local exit three generating the new
local exit three after that we apply the
bridge exits and imported Bridges The
Bridge exit are the one that are
generated from my chain that want to
transfer assets to other chains and the
imported bridges are the ones that are
generated in other chains I want to
transfer assets to my chain so we
compute them and we add them to the
local balance Tre generating a new local
balance tree finally we check the
nullifiers we check that none of this
bridge that we importing has already
been computed or has already been
Consolidated or spent and finally we
check that none of the balances in the
local balance three is lower than zero
meaning that we can compute all these
Bridges with the balances that we have
in our chain so that will be anything
from from my side thank you very much
and if you have any
question okay let's give a big round of
applause for ignasi thank you ignasi for
um for this presentation so these proofs
apart from their name they're actually
very fun apart from being pessimistic
right we have time for for a few
questions I will hit you with the red
box which you talk at this is a
microphone so please raise your hand if
you have a question for
ignasi it's not easy right yes
please okay great presentation so my
question is is this only for polygon
networks or is supposed to work no no it
will support any chain like um in the
example there were like the cdks and the
C which are polygon network but it can
support like any chain that handles a
balance of the state as I said it can
even handle Solana fantastic it doesn't
even have to be evm compatible great
because it's one of the Chang is
responsible of the state transition
more yeah there
please so um this sounds like a um
security uh measure how does this help
with like
interoperability sorry what can you
repat the last pessimistic proof sounds
from yes it's 100% security security
does it help does it simplify
interoperability in any way like you say
Solana could use pessimistic proofs like
does does will does this help sending
assets from one chain to the other that
yes it helps in the way that you are
sure that this chain has enough funds to
be transferred so you the only thing you
have to do is um verify that proof you
don't have like to if in case now on the
bridges wait that the transaction is
finalized or in case of an optimistic
roll up wait this days for the withdraw
this will not be happening that make um
the
interoperability very
fast okay thank you all that was it uh
yes we have let's go like very I'll be
here around
anyway thank you okay
well no that's it thank you
ignasi thanks again