<s>
A	O
witness-indistinguishable	B-General_Concept
proof	I-General_Concept
(	O
WIP	O
)	O
is	O
a	O
variant	O
of	O
a	O
zero-knowledge	B-Protocol
proof	I-Protocol
for	O
languages	O
in	O
NP	O
.	O
</s>
<s>
In	O
a	O
typical	O
zero-knowledge	B-Protocol
proof	I-Protocol
of	O
a	O
statement	O
,	O
the	O
prover	O
will	O
use	O
a	O
witness	O
for	O
the	O
statement	O
as	O
input	O
to	O
the	O
protocol	O
,	O
and	O
the	O
verifier	O
will	O
learn	O
nothing	O
other	O
than	O
the	O
truth	O
of	O
the	O
statement	O
.	O
</s>
<s>
Witness-indistinguishable	B-General_Concept
proof	I-General_Concept
systems	O
were	O
first	O
introduced	O
by	O
Feige	O
and	O
Shamir	O
.	O
</s>
<s>
Unlike	O
zero-knowledge	B-Protocol
proofs	I-Protocol
,	O
they	O
remain	O
secure	O
when	O
multiple	O
proofs	O
are	O
being	O
performed	O
concurrently	O
.	O
</s>
