<s>
Link	B-General_Concept
encryption	I-General_Concept
is	O
an	O
approach	O
to	O
communications	O
security	O
that	O
encrypts	O
and	O
decrypts	O
all	O
network	O
traffic	O
at	O
each	O
network	O
routing	O
point	O
(	O
e.g.	O
</s>
<s>
network	B-Protocol
switch	I-Protocol
,	O
or	O
node	O
through	O
which	O
it	O
passes	O
)	O
until	O
arrival	O
at	O
its	O
final	O
destination	O
.	O
</s>
<s>
Link	B-General_Concept
encryption	I-General_Concept
offers	O
two	O
main	O
advantages	O
:	O
</s>
<s>
if	O
the	O
communications	O
link	O
operates	O
continuously	O
and	O
carries	O
an	O
unvarying	O
level	O
of	O
traffic	O
,	O
link	B-General_Concept
encryption	I-General_Concept
defeats	O
traffic	O
analysis	O
.	O
</s>
<s>
Link	B-General_Concept
encryption	I-General_Concept
can	O
be	O
used	O
with	O
end-to-end	O
systems	O
by	O
superencrypting	O
the	O
messages	O
.	O
</s>
<s>
Bulk	B-General_Concept
encryption	I-General_Concept
refers	O
to	O
encrypting	O
a	O
large	O
number	O
of	O
circuits	O
at	O
once	O
,	O
after	O
they	O
have	O
been	O
multiplexed	B-Architecture
.	O
</s>
