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S-Box using AES Technique
H. Anusuya Baby1, Christo Ananth2
1(PG Scholar/ECE, Francis Xavier Engineering College/ Anna University , India)
2(Assistant professor/ECE, Francis Xavier Engineering College/ Anna University , India)
Abstract— To design a substitution box (S-BOX) using both
encryption and decryption. From that, the proposed system can
achieve a higher throughput and higher energy efficiency. The
S-BOX is designed by using Advanced Encryption Standard
(AES). The AES is a symmetric key standard for encryption and
decryption of blocks of data. In encryption, the AES accepts a
plaintext input, which is limited to 128 bits, and a key that can be
specified to be 128 bits to generate the Cipher text. In decryption,
the cipher text is converted to original one. By using this AES
technique the original text is highly secured and the information
is not broken by the intruder. From that, the design of S-BOX is
used to protect the message and also achieve a high throughput ,
high energy efficiency and occupy less area.
Keywords— Advanced Encryption Standard (AES),
Substitution Byte, Cryptography.
I.INTRODUCTION
Cryptography is a technique which is used to protect the
information. In 1997 the National Institute of Standards and
Technology (NIST), a branch of the US government, started
a process to identify a replacement for the Data Encryption
Standard (DES). It was generally recognized that DES was
not secure because of advances in computer processing
power. The goal of NIST was to define a replacement for
DES that could be used for non-military information security
applications by US government agencies. Of course, it was
recognized that commercial and other non-government users
would benefit from the work of NIST and that the work
would be generally adopted as a commercial standard. The
NIST invited cryptography and data security specialists from
around the world to participate in the discussion and
selection process. Five encryption algorithms were adopted
for study. Through a process of consensus the encryption
algorithm proposed by the Belgium cryptographers Joan
Daeman and Vincent Rijmen was selected. Prior to selection
Daeman and Rijmen used the name Rijndael(derived from
their names) for the algorithm. After adoption the encryption
algorithm was given the name Advanced Encryption
Standard (AES) which is in common use today.
In 2001, the National Institute of standards and
Technology (NIST) found the Advanced Encryption
Standard (AES) Technique. It can be implemented in
hardware. There are a lot of disadvantages in DES
Technique. It is insecure and the message is easily broken by
the intruder. AES Technique has been widely used in a
variety of applications such as secure communication
systems and high throughput data servers.
.
The AES encryption algorithm is a block cipher that uses
an encryption key and a several rounds of encryption. A
cipher key is an encryption algorithm that works on a single
block of data at a time. In the case of standard encryption
technique the data is 128 bits, or 16 bytes, in length. The term
―rounds‖ refers to the way in which the encryption algorithm
mixes the data re-encrypting it ten to fourteen times
depending on the length of the key.
AES encryption uses a single key as a part of the
encryption process. The key can be 128 bits (16 bytes), 192
bits (24 bytes) or 256 bits (32 bytes) in length. The term
128-bit encryption refers to the use of a 128-bit encryption
key. With AES both the encryption and the decryption are
performed using the same key. This is called a symmetric
encryption algorithm. Encryption algorithm uses two
different keys that is public and a private key. Both are
called asymmetric encryption algorithm key technique. An
encryption key is simply a binary string of data used in the
encryption process. Because the same encryption key is used
to encrypt and decrypt data, it is important to keep the
encryption key as a secret and to use the keys that are hard to
guess. Some keys are generated by software used for this
specific task. Another method is to derive a key from a pass
phrase. Good encryption systems never use a pass phrase
alone as an encryption key.
The previous techniques used in the encryption are
parallel mix column and one target one process. The parallel
mix column occupies more area and delay. The one term
process also occupies more area and delay. So the complex
parallelism is introduced.. By using this technique , a higher
energy efficiency is achieved and also delay reduction is
possible. This technique is applied for so many applications
like military purpose, computer password and so on.
The reminder of this paper is organized as follows: section
2 explains the basic types of encryption. The encryption
types involve the brief explanation about four techniques
which we have given in the abstract. Section 3 presents the
complex parallelism. The section also explains the cyclic
loop of this mechanism. Section 4 discuss the simulation
results of one target one process, parallel mix column and
Complex parallelism.
II.TECHNIQUES INVOLVE IN ENCRYPTION
AES is a symmetric encryption algorithm, and it takes
a 128-bit data as a input and performs several rounds of
transformations to generate output cipher text. It is a
computer security standard issued by NIST for protecting the
electronic data. The basic processing unit used in this AES
algorithm is byte. AES is used to encrypt/decrypt data
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blocks of 128-bits and it can be implemented in both
hardware and software. AES acts as a block cipher which
operates on fixed length group of bits of data. AES is a
stream cipher which means the plain text bits are encrypted
one and set of transformations have been applied to the bits.
It may vary during encryption process. The plain text input
and cipher output are the blocks of 128 bits. The number of
rounds depend on key size. Each 128-bit is processed in a
permutation and rotation operation. There are different
techniques involved in this encryption.
A. Substitution Byte:
It is a non- linear substitution byte. Each Byte is replaced
by another byte. This substitution Byte uses S-BOX for
generating the cipher text. This S-box involves two process.
First one is used to take the multiplicative inverse of finite
field of the matrix (i.e input data). Secondly, the Affine
Transformation is applied to the output of multiplicative
inverse. Area reduction is possible in this finite field and
finite field is used to create a compact field AES
implementation. In new technology, the S-Box can be
obtained from its truth table by using two level logic such as
sum of products and product of sum. If the above mentioned
technology is used , the primitive logic cells can be reduced
and also cell size can be optimized using synthesis tool. The
S- Box is computed from inverse of input to the original
input. The example of Affine Transformation is given by
Consider an example, 4X4 matrix is a input text and [s1
s2 s3 s4] is the inverse of the input . the remaining one [ 0
1 1 0 ] is a cipher key. The output is a [ z1 z2 z3 z4 ]. The
input is multiplied with inverse of input with a cipher key and
the output is obtained. The inverse input is the multiplicative
inverse of the given input matrix. The example of
Substitution Byte is given below.
Example of Substitution Byte input
Operation of Substitution Byte
B. Shift Row:
The technique used in this model is the transformation of
the row. Consider a 4x4 matrix, the first row of the matrix
remains unchanged. The second row , first bit is shifted to the
last one. Then the last one is shifted to the third place. Finally
the third row and forth row is finally rotated. The message is
shuffled. In otherwords, The row transformation can be
expressed as a reconstruction of the matrix using an key
expression for each element. The row expressions calculate
circular transformation .The example of shift row is given
below.
Example of Shift Row input
Operation of Shift Row
C. Mix Column:
During this process, the matrix of the input column is
shuffled. From that, the message is unbroken. It is similar to
Substitution Byte. It uses the polynomial function. It is also
based on finite field multiplication. The Mix column is based
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on the multiplication of two matrices and xor operation of
both input and cipher key.
Example of Mix Column input
Operation of Mix Column
D. Add Round Key:
The sender sends a message to the receiver using a
password (i.e key). The key is known by both sender and
receiver. The key is added to the input ( which is in the form
of cipher text ). The message is not hackable by any other
intruders and also the information is more shuffled and
secure.
III. ANALYSIS OF SYSTEM TECHNIQUES
The different types of technique involve in this encryption
and decryption. There are three techniques
A. One Target and One Process:
The input is fed to the add round key. so the key is
mixed with input (i.e cipher text). Then the output of the add
round key is shuffled with sub byte, shift row, mix column
and add round key. This process is repeated upto nine times.
Then the ouput is processed with key elongation process.
The output of key elongation is send to the final stage add
round key. Finally the cipher text is generated from the plain
text by using this OTOP technique.
B. Parallel Mix Columns:
The OTOP model is easily hackable by intruder. So the
efficiency of OTOP model is small. This process is similar
to the OTOP model. The input is fed to the add round key (i.e
cipher text). The output is fed to the sub byte and shift row.
The output of the shift row is added to the parallelizing mix
column for shuffling the message. Then the output is added
to the add round key. The process is repeated for nine times.
The key elongation process is applied to the final stage
output. The efficiency of parallel mix column is much higher
than OTOP model. The area reduction is possible in this
parallel mix column.
C. Complex Parallelism:
The input is fed to the four main blocks that is replacement
bye, row transformation, shuffle the column and xor
operation with key. The process is simulated upto nine times.
The process is optimized with complex parallelism and the
message is secure with cipher keys.
Fig 1: Complex Parallelism
First the input is fed to the xor operation with key. The
process involves in this stage is inserting a key to the input
data. Then we have to send the data to replacement byte.
Parallelizing the replacement byte is used to secure the
message. The message is much more shuffled by combining
the replacement byte. Then the next one is row
transformation. This is used to transfer or shift the data. Then
the next step is shuffle the column. It is used to shuffle the
input with key. this is done by polynomial function. Then the
last one is xor operation with key. The input is xored with
key. The process is repeated upto nine times for shuffling the
message. Finally the original text is covered by cipher key
and the output of the data is cipher text(only with cipher
keys). The cipher text information is unbroken by any other
intruder. Finally the cipher text text input is given to the
reverse process of complex parallelism. The original
message is received by the S-box. Thus The information is
secured by using complex parallelism.
IV RESULTS AND DISCUSSION
The information is encrypted by using complex
parallelism. The simulation results of OTOP model and
Parallel Mix Column are discussed below. Finally the
encrypted output of complex parallelism is also given below.
A. One Target One Process:
The input is a 128-bit. The plain text is given to the OTOP
encryption key. The cipher text is generated by using cipher
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keys. The OTOP model involves the process of SubBytes,
Shift Row, Mix Column and Add Round key. All the above
process is used to perform the message shuffling purpose.
The permutation and rotation process are done by using the
key elongation process. The message is secure and the
information is shuffled for security purposes. The number of
LUTs are reduced by 0.8%. Then the number of occupied
slices are decreased by 0.9%. The gate count is increased in
this OTOP model.
Fig 2: Compilation of OTOP model
The figure 2 shows the compilation of OTOP model. The
area utilization is 81% in this OTOP model. The delay is
calculated in the comparison table for area efficiency.
B.Parallel Mix Column:
The input is a 128-bit. The plain text is given to the
Parallel Mix Column encryption key. The cipher text is
generated by using cipher keys. The Parallel Mix Column
model involves the process of SubBytes, Shift Row, Mix
Column and Add Round key. All the above process is used to
perform the cyclic rotation for rotating the input keys . The
key elongation process is done by using key rotation. The
message is safe and the information is shuffled for security
purposes. The number of LUTs are reduced by 0.9%. Then
the number of occupied slices are decreased by 0.9%. The
gate count is increased in this Parallel Mix Column model.
Fig 3: Compilation of Parallel Mix Column
The figure 3 shows the compilation of Mix Column. The
area utilization is 96% in this Parallel Mix Column. The path
route delay is calculated
F.Complex Parallelism:
Fig 4: Compilation of S-Box
The design of S-Box is used to the protect the message.
The figure 4 shows the compilation of substitution byte.
The above figure shows the shuffling of message and also
elongating the key.
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Fig 5: Encrypted data of Complex Parallelism
The figure 5 shows the proces of complex parallelism
encryption. It will show the complex parallelism process.
The process involves the operation of one task one
processor, Parallel Mix columns and complex parallelism.
Fig 7: Decrypted data of Complex Parallelism
It implements in 167 processor using complex parallelism
technique. The process is the combination of various
techniques like Substitution Byte, Shift Row Mix Column
and Add Round Key. The message is secure and the delay is
reduced by other methods. The figure 6 and 7 show the
compilation of complex parallelism. The delay of complex
parallelism is small compared to other techniques.
Fig 8: Compilation of Complex Parallelism
The above simulation results discuss the detailed
description of three models. The comparison table of area
and delay are discussed in the below section. The table 1
discusses the comparison of area with LUTs and route path.
The table 2 discusses the comparison of delay with path and
route delay.
TABLE 1: Comparison of Area
Encryption Name
LUT
Route Path
OTOP model
21658
11
Parallel Mix
Column
21658
11
Complex
Parallelism
21634
5
The OTOP model occupies more LUT in the hardware
implementation. The number of gates in the OTOP model is
very high .The parallel mix column occupies less LUT
compare to OTOP model and high compare to complex
parallelism. The number of gates occupied in the hardware is
same as the OTOP model. The complex parallelism
technique occupies less LUTs for hardware implementation.
The number of paths in the complex parallelism are less
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compared to the both previous model. The path delay and
route delay is efficient in the complex parallelism compared
to the OTOP model and Parallel Mix Column.
TABLE 2: Comparison of Delay
Encryption
Name
Delay
Gate Delay
Path Delay
OTOP model
307.909ns
105.862ns
202.047ns
Parallel Mix
Column
232.742ns
116.830ns
115.912ns
Complex
Parallelism
232.245ns
116.683ns
115.562ns
VI. CONCLUSION
In this brief, cryptography AES technique is presented to
protect the information. To increase the efficiency, the
complex parallelism technique is used to involve the
processing of Substitution Byte, Shift Row, Mix Column and
Add Round Key. Using S- Box complex parallelism, the
original text is converted into cipher text. From that, we have
achieved a 96% energy efficiency in Complex Parallelism
Encryption technique and recovering the delay 232 ns. The
complex parallelism that merge with parallel mix column and
the one task one processor techniques are used. In future,
Complex Parallelism single loop technique is used for
recovering the original message.
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Vol. 3 Issue 3, March - 2014
International Journal of Engineering Research & Technology (IJERT)
ISSN: 2278-0181
www.ijert.orgIJERTV3IS030404