Cryptography Reference
In-Depth Information
Input
: an encryption scheme
C
, a fixed message
x
Parameter
:
,
m
,
t
Preprocessing
1:
for
s
=
1to
do
pick a reduction function
R
s
at random and define
f
s
:
k
→
2:
R
s
(
C
k
(
x
))
for
i
=
1to
m
do
3:
pick
k
at random
4:
k
k
←
5:
for
j
=
1to
t
do
6:
compute
k
←
f
s
(
k
)
7:
end for
8:
k
) in table
T
s
insert (
k
,
9:
10:
end for
11:
end for
Figure 2.37.
Time-Memory tradeoff (Preprocessing).
Attack
Attack input
:
y
=
C
K
(
x
)
1:
for
s
=
1to
do
set
i
to 0
2:
set
k
to
R
s
(
y
)
3:
,.
<
while
T
s
contains no (
k
) entry and
i
t
do
4:
increment
i
5:
k
←
f
s
(
k
)
6:
end while
7:
if
T
s
contains a (
k
,.
) entry
then
8:
k
) entry from table
T
s
get the (
k
,
9:
while
C
k
(
x
)
=
y
and
i
<
t
do
10:
increment
i
11:
k
←
f
s
(
k
)
12:
end while
13:
if
C
k
(
x
)
=
y
then
14:
15:
yield
k
16:
end if
17:
end if
18:
end for
19:
abort: the attack failed
Figure 2.38.
Time-Memory tradeoff (Attack).
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