Information Technology Reference
In-Depth Information
320
312
032
For a 3 cell GF(2
2
)
SACA
, T is:
Step 3.
Construct
SACA
by implementing the result ofTheorem 3.
3 Cellular Automata Based Authentication (CAA)
Scheme for Message/Image
The schemes for message and image authentication are noted along with proof
ofrobustness against the attacks. The GF(2) CA based authentication scheme
proposed in [9] is insecure against attacks based on Differential Cryptanalysis.
The proposed scheme overcomes the problem.
3.1
SACA
as One-Way Hash Function Generator
The proposed scheme employs
keyed one-way hash
function based authentication
using GF(2
p
)
SACA
and its dual
SACA
. The one-way hash function maps a
secret key and an arbitrary length input message data to a fixed length hash
output referred to as message digest .
3.2
CAA for Digital Message
Let, A has a message M to send to B and they share a common secret key K.
A calculates message digest
C
K
(
M
) from M, and K employing one way
SACA
based hash function. Message M and digest
C
K
(
M
) are transmitted to B where
B performs the same function on the received message to generate a new digest
C
K
(
M
). The message gets authenticated if
C
K
(
M
) and
C
K
(
M
) matches.
Algorithm 1
Generate Message Digest
Input
: Message M of length |M | bits; Private key P: n × p bits :
- n cell GF(
2
p
) SACA and its dual SACA
Output
: Message Digest: n × p bits
Step 1:
Group Message M into k blocks { M
1
, M
2
, ... M
k
} each of length n
symbol (S
1
, S
2
, ..., S
n
)inGF(
2
p
)
Let P
1
=
P (Private Key)
For(i=1 to k)
{
Step 2:
Form a tridiagonal matrix CA
M
i
whose n diagonal elements are
n-symbols of M
i
; off diagonal values are 1 and the remaining all values are zero
Step 3:
Run each of the CAs for one step:
(a)
Run CA
M
i
with P
i
as seed to obtain P
i
1
(b)
Run SACA with P
i
1
as seed to obtain P
i
2
(c)
Run SACA with P
i
2
as seed to obtain P
i
3
