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From YouTube: Predicate Proofs: Tips on Proving Without Revealing - Michael Bailey, Paramount Software Solutions
Description
Predicate Proofs: Tips on Proving Without Revealing - Michael Bailey, Paramount Software Solutions
Indy and Aries have been designed with strong privacy protection as a foundational principle. In addition to putting personal information under the control of the end users, zero-knowledge and predicate proofs are used to keep users from needing to provide more than the minimum amount of information needed to accomplish their purposes. For example, there is no need for a bartender to know an exact birth date to prove age-based qualification to purchase an alcoholic beverage. Common implementations of age-based qualification depend on an “age” field in a verifiable credential, instead of on the birth date. A better solution is to base the credential on a birth date that is in a human-readable format that is also amenable to being processed by the current predicate proof technology. A demonstration of predicate proofs using such a format for dates, ISO 8601, will be presented.
Sessions Details & Slides (if available)- https://sched.co/j3cP
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----
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A
All
right,
let's
get
this
show
on
the
road
first,
just
to
welcome
to
everybody,
I'm
glad
to
be
able
to
talk
to
you.
This
is
kind
of
a
strange
way
to
do
it.
As
far
as
I'm
concerned,
I'm
much
more
used
to
talking
to
groups
of
people
live
and
having
some
interaction,
which
will
be
fairly
limited
in
this
context.
A
As
far
as
the
tools
that
we
have
here
for
our
interaction,
I
I'm
going
to
be
setting
my
display
so
that
I
will
be
looking
in
the
q
a
rather
than
in
the
chat.
So
if
you
have
questions,
please
post
them
there
and
you
can
gossip
about
me
all
you
want
in
the
chat-
and
I
probably
won't
see
it-
I'm
I'm
mike
bailey,
I'm
a
blockchain
architect
for
paramount
software
solutions.
A
I'm
also
an
assistant
professor
at
utah
state
university.
So
I
just
have
to
mention:
go
jazz
just
you
know,
because
that's
where
I'm
from
right
and
and
and
for
those
of
you
who
are
really
not
sports
fans
they're
in
the
nba
playoffs
right
now,
I'm
doing
very
well
all
right.
So
today,
what
I'm
going
to
be
talking
about
are
predicate
proofs
and-
and
I
kind
of
consider
them
almost
a
superpower
when
we
talk
about
zero
knowledge
proofs.
A
What
people
here
in
the
community,
in
particular,
tend
to
think
about
is,
is
controlled
disclosure,
where,
if
I
have
a
credential
that
has
lots
of
different
fields
in
it.
Maybe
I
just
I'm
going
to
share
one
field
with
you:
predicates
takes
it
to
a
whole
new
level
beyond
that,
so
so
I'm
gonna
introduce
for
those
of
you
who
aren't
already
familiar
with
what
credit
proofs
are.
I
will
introduce
them
and
give
you
some
tips
on
how
to
use
them,
but
I'll
actually
just
mention
towards
the
end.
A
A
So
this
is
one
of
the
key
tools
that
we
are
that
we
use
when
we're
trying
to
preserve
privacy.
Typically,
almost
everybody
who
gives
a
presentation
talking
about
this
type
of
thing.
They
give
the
driver's
license
example
and
show
all
the
drivers
license
data
and
how,
if
you're,
just
trying
to
buy
a
drink
in
a
bar.
When
you
hand
somebody
your
driver's
license,
you're,
giving
them
far
too
much
information
that
could
be
compromising
your
privacy.
A
A
A
If
all
you're
trying
to
do
is
show
that
you
graduated
your
gpa,
your
major,
you
know
what,
if
you're,
maybe
not
real
comfortable
with
the
the
fact
that
you
were
desperate
to
graduate,
and
so
you
dropped
out
of
civil
engineering
and
went
into
basket
weaving
instead
to
graduate
well
telling
people
your
your
major
is
not
required,
and
maybe
your
scholarships
and
and
pell
grants
and
things
like
that
might
be
on
there
not
required.
All
you
really
need
perhaps
is
if
we're
doing
controlled
disclosure
type
of
xero
knowledge
proofs.
A
A
Maybe
you
don't
want
to
show
that
you
graduated
in
in
1990,
or
something
like
that
you'd
rather
be
assumed
to
be
a
little
bit
younger.
So
you
don't
even
want
to
give
me
the
graduation
date,
so
the
basic,
zero
knowledge
proof
that
will
just
selectively
disclose
just
one
field
will
get
you
part
of
the
way
there.
A
A
That
the
transcript
came
from
the
university
it
was
issued
by
the
university
it
was
signed
by
the
university.
We
know
that
we
could
give
them
back.
We
we
could
demonstrate
to
somebody
that
we
have
this
transcript,
that
is
digitally
signed
by
the
university,
but
isn't
it
much
better
if
I
just
give
them
a
boolean,
yes
or
no,
but
be
able
to
trace
back
the
the
bullion
value
as
being
derived
from
something
that
was
digitally
signed
by
the
university
and
not
just
me
saying
it
okay.
A
A
A
For
example,
you
must
be
50
to
join
aarp.
Can
you
is
that
derived
down
to
a
yes
or
no
answer?
Yes,
okay.
So
this
is
something
that
if
you
have
a
credential,
you
could
check
an
age
on
a
credential
and
see
that
you're,
you're,
50
or
older.
You
can
join
aarp
notice.
How
cleverly
I'm
still
shying
away
from
the
you
know,
21
to
buy
a
drink
type,
of
example,
all
right
height.
A
If
you
had
something
that
a
credential
from
the
dmv
or
something
that
says
you're
this
tall,
well,
you
could
prove
height
or
if
you
had
weight
insurance
discount.
If
you
have
a
body
mass
index
less
than
28
okay,
so
so
that
would
be
something
you
could
do
a
true
or
false
and
provide
a
predator
proof
on
this
last
one
is
actually
one
that
a
customer
of
mine
was
interested
in.
They
were
actually
the
other
way
around
this.
They
said
we
service
the
following
states.
A
We
don't
really
want
to
know
which
state
they're
in
we
just
want
to
know
that
they're
from
one
of
these
states
can
I
give
you
a
list
of
of
states
and
and
have
a
predicate,
come
back
and
say
true
or
false.
This
person
is
in
one
of
your
service
area
states,
okay
or,
as
this
example
here
says,
offer
void.
If
you're
in
a
select
state
you
could
you
can
reverse
that,
so
these
are
potential,
predicate
objects
or
examples
of
them,
so
so
really
they
boil
down
to.
I
came
up
with
these.
A
If
anyone
else
can
think
of
other
things.
These
are
the
ones
that
I've
seen.
Customers
come
to
me
and
say
hey.
I
would
like
a
predicate
that
does
this
sort
of
thing
so,
for
example,
greater
than
or
less
than
would
be,
if
you're
over
50,
if
you're
over
21
those
types
of
numerical
type
of
of
greater
than
less
than
are
examples
of
of
predicate
type
of
operators
equal
to
is
is
another
one.
A
A
A
I
guess
an
example
would
be
if
you're
trying
to
prove
somebody
is
a
citizen
of
the
united
states.
Well,
one
way
to
tell
that
would
be
if
they
have
a
social
security
number.
Maybe
you
don't
really
even
want
to
know
their
social
security
number,
but
just
tell
me:
do
you
have
a
credential
with
a
social
security
from
social
security
administration
and
if
so,
they're
a
citizen-
and
you
know
things
go
forward,
so
just
possession
of
a
credential.
A
A
Let's
talk
about
what
we
do
have
well.
The
the
first
thing
I
ought
to
mention
is
one
of
the
reasons
that
we're
here
at
a
hyper
ledger
conference.
Talking
about
this
is
that
we
do
predicate
proofs
and
current
hyperledger
indie
and
aries
implementations,
okay,
so
state
of
the
art
we
we
have
this,
but
there
is
a
limitation
on
what
we
have
right
now.
A
All
we
have
implemented
are
numeric.
So
if
I
want
to
see
if
somebody
is
a
member
of
a
state
or
something
like
that,
a
member
set
like
that
that
isn't
you
know
something
that
can
be
just
defined.
Numerically
current
implementations
you're
out
of
luck,
I
can
tell
greater
than
or
less
than
that's
pretty
much
it.
A
Okay,
it's
based
on
cl,
comminish,
okay,
I'm
not
gonna,
I'm
I'm
gonna
hack,
this
I'll
just
say
it's
based
on
sealed
signatures
and
reading
through
a
a
recent
document
put
out
by
by
a
identity,
woman.
She
she
said:
json's
ekpcl
generates
a
numeric
representation
of
each
field
and
then
signs
both
the
numeric
and
text
representation
of
the
statements
using
a
seal
signature.
A
So
what
this
is
basically
saying
is
that
we
we
are
going
to
the
degree
that
we
actually
are
are
signing
things
twice
in
order
to
make
this
thing
work
in
these
implementations
and
indian
aries,
one
of
which
is
a
numeric
representation,
and
that
allows
us
to
use
these
predicates
in
order
to
do
it.
So
so
there
are
some.
A
A
So,
for
example,
even
if
we
use
the
most
computer
slash
human
friendly
format
for
for
representing
dates,
I
like
the
iso,
8601
format.
Okay,
it
puts
the
year
first
and
then
the
month
of
the
day.
So
this
is
today's
date
and
as
long
as
a
person
knows
what
to
expect,
that's
pretty
human
readable,
and
it's
also
very
good
for
representing
things
in
a
way
that
computers
can
operate
on
them,
because
this
is
in
a
a
little
endian
format.
That
is
able
to
be.
A
A
202106
that
would
just
increment
that
last
little
eight
and
hexadecimal
to
a
nine,
and
I
can
easily
tell
with
a
computer,
I
can
say:
is
this
greater
than
or
less
than
and
and
and
that
will
work
for
me,
however,
the
current
implementations
of
what
is
in
indian
aries
doesn't
even
do
this
as
soon
as
you
put
those
little
dashes
in
there,
then
indies
and
indy
and
aries
implementations
will
say
well.
That
is
a
text
string.
That
is
not
a
numeric,
and
so,
if
you
try
to
do
a
predicate
proof,
it
will
fail.
A
So
there
are
definitely
limitations
on
the
current
implementation
and
actually,
when
I
first
proposed
this
little
presentation
that
was
going
to
be
the
thrust
of
my
entire
presentation
is
that
we
need
to
fix
it
so
that
we
could
take
text
like
this,
convert
it
into
just
a
hexadecimal
representation
of
it,
and
we
would
be
able
to
if
we,
if
we
just
tweak
indian
aries
just
a
little
bit,
we
would
be
able
to
do
predicate
proofs
on
strings
like
this.
That
are
also
human
readable,
because
dates
is
one.
A
The
main
thing
that
everybody
wants
is
stuff
for,
but
that
being
said
as
you'll
see
later
in
the
presentation,
some
of
the
my
reasoning
has
has
been
overcome
and
we're
we're
going
to
go
on
and
and
leave
this
for
now
just
realize
that
there
isn't
that
limitation
right
now,
I'm
going
to
do
a
brief,
little
demonstration
of
a
way
to
work
around
this
to
some
degree.
Right
so
say
that
I
want
to
get
a
transcript.
A
A
I
I
just
put
graduation
date
gpa
and
major
and
okay,
and
I
want
to
be
able
to
prove
that
I've
graduated
before
after
a
certain
date.
Okay.
Now,
in
order
to
do
this,
I'm
going
to
add
an
additional
field
to
the
credential,
I'm
going
to
call
it
a
date
code.
You
can
see
it's
really
the
utf-8,
except
that
I
omitted
the
dashes
all
right,
and
so,
if
I
do
it
like
this,
I
can
issue
a
predicate
proof
on
that
date.
Code.
A
A
Okay,
if
it's
not
something
that
is
immediately
recognizable
as
a
date
and
and
you
have
to
have
a
graduation
date
and
that
rather
than
just
having
one
or
the
other
all
right,
so
there
there's
there's
the
and-
and
this
is
actually
working
code
here-
I'm
not
going
to
take
the
chance
of
of
it
in
the
in
this
little
presentation.
That's
very
brief,
but
but
we
this
is
implemented.
A
A
Okay,
aries
is
getting
that
implementation
is
active
and
ongoing.
It's
one
of
the
most
exciting
things
happening
in
the
aries
community
right
now
and
here's
the
bad
news
predict
proofs
are
going
to
be
a
casualty
of
this.
I
I
learned
this
after
I
proposed
this
presentation,
but
I
think
this
presentation
is
still
worthwhile,
because
I
think
it's
going
to
be
a
temporary
thing.
They
will
be
back
now.
Why
are
they
a
casualty
of
it?
A
Talking
to
some
cryptographer
friends-
and
I
will
not
put
my
my
self
in
that
camp-
but
talking
to
some
cryptographer
friends-
they
are
doable,
but
it's
just
going
to
be
something
that's
on
the
backlog
for
the
time
being,
it's
it's
not
something
immediately.
Obvious
and
they're
gonna
have
to
go
away
and
and
and
figure
it
out.
A
A
I
I
guess
I
should
say
credential
definitions,
the
these
credential
definitions
are
basically
all
the
keys
for
every
field
that
go
into
the
the
credentials
that
you're
going
to
issue,
and
so
each
individual
field,
each
individual
attribute,
has
its
own
key
set
and-
and
those
are
all
being
put
into
this
into
these
credential
definitions
that
need
to
be
stored.
Somewhere
with
json
ld
and
vbs,
plus
there
is
a
deterministic
key
expansion.
All
you
have
to
do
is
store
one
key
for
the
entire
credential
class
that
you're
going
to
issue.
A
So
you
don't
have
to
store
these
large
precomputed
credentials
that
have
lots
of
individual
keys
in
them.
So
that's
an
advantage.
The
biggest
advantage
is
probably
the
rich
tech
rich
document
for
format
rdf
that
allows
hierarchical
schemas.
So
if
you
have
a
schema
that
somebody
has
come
up
with
for
for
something
and
then
somebody
wants
to
incorporate
that
scheme
into
another
schema,
json
ld
will
support
that.
A
I
I
particularly
like
the
multilingual
capabilities,
because,
if
you
think
of
it,
you
could,
if
you
have
hierarchical
schemas,
you
could
have
a
base
schema
and
then
have
okay,
another
schema
that
is
going
to
incorporate
that
for
english
another,
and
it's
also
going
to
incorporate
it
for
spanish,
and
it's
also
going
to
incorporate
it
for
bengali
and
have
multiple
copies
of
the
same
schema
one
for
each
language
that
you're
going
to
issue
credentials
in
and
that
way
this.
This
will
provide
multilingual
capabilities
in
your
credentials.
A
A
A
A
So,
for
example,
going
back
to
this,
I
wouldn't
have
to
show
a
separate
date
code.
I
could
have
in
my
credentials
I'm
displaying
to
the
user
the
values
in
human
readable
format,
but
I
could
have
hidden
in
my
same
credential
the
exact
same
values
for
the
exact
same
fields
in
a
more
machine,
readable
format
such
as
this,
and
that
would
be
supported
now
with
the
json
ld.
A
A
So
in
conclusion,
I'm
nearly
at
the
end
of
my
time
a
limited
form
of
predicate
proofs
exist
in
indian
aries
they,
but
they
are
going
to
be
lost
until
we
figure
out
how
to
do
predators
for
bbs
plus
signatures,
which
is
I'm
told,
is
doable
but
needs
to
be
added
to
the
to-do
list,
and
potentially
they
will
be
better
than
ever.
When
this
happens.
A
A
Indy
has
historically
stored,
credential
type
of
metadata,
the
different
types
of
keys
and
such
needed
for
digital
signatures,
the
public
part
of
those
keys
onto
a
blockchain,
the
indie
project
in
particular,
and
so
so
this
this
particular
project,
even
though
a
lot
of
it
seems
like
it
is
external
to
blockchain,
it
has
originated
in
hyperledger
we're
ahead
of
the
rest
of
the
world
and
a
lot
of
this
stuff
and
it's
exciting
stuff,
and
it
still
has.
There
are
still
a
lot
of
indie
legends
like
sovereign
and
things
that
are
out
there.
A
Okay,
as
far
as
indy
there's
two
different
types,
the
question
is:
it's
our
development
in
indy
for
json,
ld,
ldbsplus,
there's
two
different
parts
of
indy:
there's
the
india
sdk
and
in
the
sdk
was
the
part
that
was
used
to
be
used
to
develop
agents.
It
really
is
not
being
continued
to
be
developed
much
anymore,
then
there's
the
indy
as
far
as
the
ledgers
that
are
used
to
to
store
the
public
keys
and
there
will
not
be
a
much
need
for
any
development
on
the
indy
ledger.