<s>
A	O
Schnorr	B-Algorithm
group	I-Algorithm
,	O
proposed	O
by	O
Claus	O
P	O
.	O
Schnorr	O
,	O
is	O
a	O
large	O
prime-order	O
subgroup	O
of	O
,	O
the	O
multiplicative	O
group	O
of	O
integers	O
modulo	O
for	O
some	O
prime	O
.	O
</s>
<s>
Schnorr	B-Algorithm
groups	I-Algorithm
are	O
useful	O
in	O
discrete	O
log	O
based	O
cryptosystems	B-General_Concept
including	O
Schnorr	B-Algorithm
signatures	I-Algorithm
and	O
DSA	O
.	O
</s>
<s>
Because	O
the	O
Schnorr	B-Algorithm
group	I-Algorithm
is	O
of	O
prime	O
order	O
,	O
it	O
has	O
no	O
non-trivial	O
proper	O
subgroups	O
,	O
thwarting	O
confinement	O
attacks	O
due	O
to	O
small	O
subgroups	O
.	O
</s>
<s>
Implementations	O
of	O
protocols	O
that	O
use	O
Schnorr	B-Algorithm
groups	I-Algorithm
must	O
verify	O
where	O
appropriate	O
that	O
integers	O
supplied	O
by	O
other	O
parties	O
are	O
in	O
fact	O
members	O
of	O
the	O
Schnorr	B-Algorithm
group	I-Algorithm
;	O
is	O
a	O
member	O
of	O
the	O
group	O
if	O
and	O
.	O
</s>
