<s>
Veriexec	B-Application
is	O
a	O
file-signing	O
scheme	O
for	O
the	O
NetBSD	B-Device
operating	O
system	O
.	O
</s>
<s>
It	O
introduces	O
a	O
special	O
device	O
node	O
(	O
)	O
through	O
which	O
a	O
signature	O
list	O
can	O
be	O
loaded	O
into	O
the	O
kernel	B-Operating_System
.	O
</s>
<s>
The	O
list	O
contains	O
file	B-Application
paths	I-Application
,	O
together	O
with	O
hashes	B-Algorithm
and	O
an	O
expected	O
file	O
type	O
(	O
"	O
DIRECT	O
"	O
for	O
executables	O
,	O
"	O
INDIRECT	O
"	O
for	O
scripts	O
and	O
"	O
FILE	O
"	O
for	O
shared	O
libraries	O
and	O
regular	O
files	O
)	O
.	O
</s>
<s>
The	O
kernel	B-Operating_System
then	O
verifies	O
the	O
contents	O
of	O
the	O
signed	O
files	O
against	O
their	O
hashes	B-Algorithm
just	O
before	O
they	O
are	O
opened	O
in	O
an	O
exec( )	O
or	O
open( )	O
system	B-Operating_System
call	I-Operating_System
.	O
</s>
<s>
When	O
Veriexec	B-Application
is	O
enabled	O
at	O
level	O
0	O
,	O
the	O
kernel	B-Operating_System
will	O
simply	O
warn	O
about	O
signature	O
mismatches	O
.	O
</s>
<s>
At	O
the	O
highest	O
,	O
level	O
3	O
,	O
the	O
kernel	B-Operating_System
will	O
not	O
allow	O
unsigned	O
files	O
to	O
be	O
accessed	O
at	O
all	O
.	O
</s>
