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https://archive.devcon.org/archive/watch/6/rate-limiting-nullifier/
RLN (Rate limiting nullifier) is a construct based on zero-knowledge proofs that enable spam prevention mechanisms for decentralized, anonymous environments.
Speaker(s): AtHeartEngineer
Skill level: Intermediate
Track: ZKPs: Privacy, Identity, Infrastructure, & More
Keywords: zk,spam,anonymous
Follow us: https://twitter.com/efdevcon, https://twitter.com/ethereum
Learn more about devcon: https://www.devcon.org/
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Devcon is the Ethereum conference for developers, researchers, thinkers, and makers.
Devcon 6 was held in Bogotá, Colombia on Oct 11 - 14, 2022.
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A
A
There
we
go
so
our
land
has
been
mentioned
quite
a
few
times
throughout
presentations
this
week
and
I
wanted
to
kind
of
talk
about
how
it
worked
like
what's
under
the
hood
in
a
way
that's
like
accessible
to
most
people,
so
the
key
part
is
the
rate
limiting.
So
it's
basically
controlling
like
how
fast
you
can
interact
with
the
system.
A
So
it
is
made
up
of
a
couple
of
things
so
semaphore,
which
is
the
talk
before
this,
which
is
basically
just
proving
you're
part
of
an
anonymity
set
without
revealing
Who
You
Are
samir's
secret
sharing
scheme,
which
is
the
majority
of
this
talk,
and
some
time
or
event
delineation,
which
I'll
get
into
in
a
minute,
there's
kind
of
three
stages
to
how
Arlen
works.
So
there's
a
registration
process
so
like
joining,
which
is
basically
just
a
Markle
tree
and
signaling,
which
is
your
actual
sending
of
messages.
A
Then
there
is
the
slashing
or
secret
recovery.
So
yeah
so,
like
I
just
said,
the
registration
process
is
just
the
Merkle
tree,
so
this
is
basically
what
semaphore
is
so
it's
just
proving
you're
part
of
and
and
an
anonymity
Set,
and
this
can
be
done
on
or
off
chain.
So
the
signaling
part.
This
is
kind
of
the
the
meat
of
all
of
this
is
so
it's
a
circum
circuit
and
the
first
public
input
is
the
epoch
which
is
like
a
time
or
it
could
be
like
a
post
on
Reddit
or
something
like
that.
A
Just
some
delineation
in
a
time
or
an
event,
and
then
the
actual
message
and
then
a
secret
key,
and
out
of
that
comes
proof
that
your
Epoch
and
your
message
are
accurate
and
you
know
verified
with
what
you
put
into
it.
It
proves
that
you
belong
to
that
that
Merkle
tree
that
membership
group
and
it
spits
out
a
secret
chair.
A
So
this
secret
chair
is
one
of
the
most
important
parts
of
of
how
rln
Works.
Basically,
if
you
have
a
a
secret,
you
can
plot
that
on
a
graph
and
on
the
y-axis
you
can.
You
know
this
is
basically
how
Sumer
secret
sharing
Works
the
random,
so
you
have
to
have
a
random
point
to
construct
your
shares
and
that
is
derived
from
the
epoch
and
the
shares
are
generated
from
the
message
hash.
A
So
the
shares
basically
the
the
whole
idea
behind
Superior
secret
sharing
scheme
is
you
have
you
have
a
secret,
you
break
it
up
into
parts
and
you
distribute
those
parts
publicly
and
if
you
have
enough
of
them,
you
can
reconstruct
the
secret.
So,
with
these
two
shares
you
can
reconstruct
where
that
line
is
so
I'm
going
to
go
through
how
that
works.
So
if
you
have
one
share,
you
really
don't
know
where
that
line
is
right.
A
If
you
have
two
shares,
then
you
can
see
where
it
crosses
the
y-axis
and
you
can
determine
what
the
secret
is.
So
if
someone
basically
submits
too
many
messages
too
fast,
like
you
know,
within
a
15
second
time
period
or
whatever
your
your
rate
limiting
is,
then
someone
can
reconstruct
your
your
secret,
your
private
key,
basically
figure
out
your
identity,
commitment
and
withdraw.
A
You
know
a
steak
or
something
like
that,
and
this
can
be
split
up
into
multiple
pieces.
It
doesn't
just
have
to
be
a
linear
function.
This
could
be
a
polynomial,
so
you
can
have
like
multiple
shares
that
you
need
to
be
able
to
recover.
So
you
can
say,
like
you
know,
a
person
can
send
15
messages
per
day,
but
that's
it.
So
this
is
the
actual
circuit.
I
know
this
looks
a
little
confusing,
but
if
you
kind
of
just
look
and
see
how
all
this
is
assembled,
it's
really
not
that
bad.
A
So
you
have
the
epoch,
the
message
and
the
secret
key
going
in
and
the
center
part
here
I
have
a
little
laser
pointer.
This
center
part
is
the
shimir
secret
sharing
scheme
and
the
right
side.
This
is
basically
just
the
construction
of
the
identity
commitment,
so
it's
your
like
public
identifier
for
being
anonymous
and
the
left
side.
A
So
this
is
just
the
this
is
nullifier,
so
it's
basically
the
equivalent
of
like
a
nonce
and
some
use
cases
for
this
that
we
thought
of
is
you
know
you
could
do
like
auctions,
where
you
can
have
only
so
many
bids
per
item
or
whatever
bits
per
user.
You
can
have
a
bulletin
board
system
like
Reddit,
where
you
can
only
have
you
know
you
can
only
comment
once
per
post
or
you
know,
once
per
level
of
post.
A
This
we've
also
thought
about
using
this
for
preventing
denial
of
surface
attacks
for
something
like
cloudflare,
where
we
can
do
that
anonymously
and
decentralized,
and
then
so.
This
is
also
used
in
a
couple
applications
that
the
PSE
has
developed
like
skidder.
So
like
we
have
a.
We
have
ZK
chat
in
there,
so
it's
Anonymous
chat
where
it's
rate
limited,
and
so
we
have
a
JavaScript
library
for
this.
A
We're
working
on
a
rush
library
in
collaboration
with
the
VAC
team
and
we're
probably
gonna
write
a
python
version
and
a
couple
other
bindings
for
languages
yeah.
So
if
you
want
to
look
at
the
documentation
or
the
code,
there's
the
QR
code
and
if
you
have
any
questions,
you
can
join
our
Discord
again
I'm
at
heart,
engineer
and
yeah.
Thank
you.
Thank.