A NEW APPROACH TOWARDS INFORMATION SECURITY BASED ON DNA CRYPTOGRAPHY

SRI SAI COLLEGE OF ENGINEERING ANDTECHNOLOGY
Badhani,Pathankot,Punjab,India
M.Tech. Thesis
A NEWAPPROACHTOWARDS
INFORMATION SECURITY BASEDON
DNA CRYPTOGRAPHY
Presented in partial fulfillment of the requirements for the degree of
Master of Technology in Computer Science & Engineering
PRESENTING BY: ABHISHEK
MAJUMDAR(1269890)
UNDER THE SUPERVISION OF
PROF . MEENAKSHI SHARMA
Date: Jun 7, 2015
PUNJABTECHNICAL UNIVERSITY
Jalandhar- Kapurthala Highway, Jalandhar

Abstract
 Data security is one of the most significant issues of
data transmission and communication of today's world.
 In order to make secure data the researchers are
working on the evolvement of new cryptographic
algorithms.
 One of the efficient directions of achieving security data
communication is DNA based Cryptography.
 The proposed encoding and decoding process is based
on the use of the DNA sequencing string of the DNA
strands. The encoded text that is cipher text produced
by the encoding algorithm is looks similar with the
biological structure of the DNA strands sequence.
CSE Dept. SSCET, Badhani
2

Objective
 Encrypt the plain text into DNA sequence
(cipher text ) using new DNA encryption
technique.
 Decrypt this cipher text using DNA decryption
technique.
 Propose a new model to DNA cryptography
3

Outline
 Introduction
 Basis of cryptography
 Brief idea of DNA
 DNA Cryptography
 Related Works
 Proposed Method
 Key Selection and Generation
 Encryption
 Algorithmic steps
 Work flow
 Ensuring Integrity
 Algorithmic steps
 Strength
 Conclusion
 Future Scope
 References
4

 Cryptography: The art of protecting
information by transforming Plain Text into an
unreadable format.
 Those who possess the secret key can
decrypt the message .
 Encrypted messages can sometimes broken
by Cryptanalysis .
Basis of Cryptography
5

Basis of Cryptography contd….
6
Figure 1.Basic Structure of Cryptography

Symmetric Cipher Model
7
Figure 2. Simplified Model of Symmetric Encryption

Intruder’s Attack
Basis of Cryptography Intruder’s
Attack
8
Figure 3.Threat of Intruder

Background Study
 Genetic Code: Information encoded within
genetic material (DNA or mRNA base) .
 DNA sequence : Order of nucleotide bases in
the DNA molecule.
ATTAGCCTTATGCATGAACC
9

Brief idea of DNA
 Deoxyribo Nucleic Acid
 Carrier of the genetic information
 A double stranded molecule.
 Each strand is based on 4 bases:
 Adenine (A)
 Thymine (T)
 Cytosine (C)
 Guanine (G)
DNA sequence
10

Brief idea of DNA Base Pairing
 Adenine (A) pairs with Thymine (T)
 Guanine (G) pairs with Cytosine(C)
Hydrogen
Bonds
Figure 4. DNA Base Pairing

DNA Cryptography
 First introduced by L. Adleman in 1990s.
 Plaintext message Encoded into DNA
sequences.
 Based on one-time-pads .
12

Related works
Bibhash Roy et al.
The use of round in the encoding scheme is taken from this
work.
Each time the user has to validate and authenticate them self
while accessing the service of the algorithm and every time a
new key is generated randomly for data communication.
The encryption scheme is designed based on the property of
DNA sequencing. It is much more difficult to do cryptanalyst the
coded form of message without knowing the selected DNA
sequence.
Mohammad Reza Abbasy et al.
Common DNA sequence is shared between the sender and
the receiver. Then the occurrences of the DNA representation of
the plain text in the reference DNA sequence is listed by using
an indexing method where every couple of nucleotides in DNA
reference sequence is given an index number.
13

Related works contd…
H.Z. Hsu and R.C.T.Lee et al.
They presented three methods, the insertion method, the complementary pair method
and the substitution method.
For each method, they secretly select a reference DNA sequence, transform the
sequence into binary bits using binary coding scheme then sub divide the reference
sequence bits into segments of fixed number of bits and incorporate the secret message
into each segments.
After incorporating the message into the DNA sequence, the encoded form of the
message is transform into the DNA sequence form, send this encoded message
together with many other DNA, or DNA-like sequences to the receiver.
The receiver is able to identify the particular desired sequence that is hidden in the
encoded message and ignore all of the other sequences. Thus receiver could be able to
extract the message.
The process of encryption containing different information along with the original
message has also been extracted.
14

Sabari Pramaniket al.
A single stranded DNA string used as the secret key whose length
depends on the plain text and they used it to encrypt the plain text.
They divided the plain text into a number of DNA plain text packets
and attach the packet sequence number with each packet.
Nirmalya Karet al
A method in which rather than sharing the actual keys directly
between the sender and receiver, session keys are shared between
the sender and the receiver that actually bears the information about
the encryption keys.
They had designed an encryption scheme by using the technologies
of DNA synthesis and moreover extra bits and the faked DNA
sequence were padded within the cipher text that made the message
more secure from intruders.
15

Amal Khalifa et al.
Discussed a method of text hiding where the text is encrypted using
amino acid and DNA based playfair cipher and also use
complementary rules to hide the resultant cipher text in a DNA
sequence.
Wang, Xing et al.
A new way to show how cryptography works with DNA computing, it
can transmit message securely and effectively.
They have used RSA algorithm belongs to asymmetric key
cryptography along with DNA computing theory.
Suman Chakraborty et al.
Incorporated an idea of DNA based image encryption using soduko
solution matrix to perform some computations on behalf of the
message.CSE Dept. SSCET, Badhani
16

Proposed method
 3 phases :
 Key Generation and Selection
 256 bit key
 Round key generation
 Encryption of Plain Text:
 Block Ciphering
 DNA Encoding, Primer padding, Hash Mapping
 Ensuring Integrity:
 Shared Hash Function.
17

Key Selection & Generation Algorithmic
step
Input: A randomly chosen 256 bit key
Output: 4 round encryption keys
 Step 1. Let, K be the key, K= '1011 1010 0011 0011 1100 1100 1010 0011 0000
0000 0000 0000 1111 1111 1111 1111 1110 1110 1001 0011 0000 1010 1111 0100
1011 1100 0101 1001 0011 1011 0001 1010 0011 1001 0011 0100 1010 1100 1001
1010 0000 0001 1000 1010 1111 0001 1010 0101 0000 0001 1010 1100 1000 1111
1000 1111 0001 1111 0011 0010 1100 0001 1111 1000‘
 Step2. Transformation of key values into matrix row wise
Table 1. Key MatrixCSE Dept. SSCET, Badhani
18

step
 Step 3. Read the key values column wise (two columns at a time), label the
sub-keys with DNA bases (A, T, C, G) as follows:
A= '1011 0000 1110 1011 0011 0000 0000 0001 1010 0000 1110 1100 1001
0001 0001 1111'
T= '0011 0000 1001 0101 0011 1000 1010 0011 0011 0000 0011 1001 0100
1010 1100 0010'
C= '1100 1111 0000 0011 1010 1111 1000 1100 1100 1111 1010 1011 1100
0001 1111 0001'
G= '1010 1111 1111 0001 1001 1010 1000 1111 0011 1111 0100 1010 1010
0101 1111 1000'
19

step
 Step 4. Let, randomly selected DNA sequence with DNA bases be 'TGCA'
then,
Round 1 key:
Key1=TGCA = '0011 0000 1001 0101 0011 1000 1010 0011 0011 0000 0011 1001
0100 1010 1100 0010 1010 1111 1111 0001 1001 1010 1000 1111 0011 1111 0100
1010 1010 0101 1111 1000 1100 1111 0000 0011 1010 1111 1000 1100 1100 1111
1010 1011 1100 0001 1111 0001 1011 0000 1110 1011 0011 0000 0000 0001 1010
0000 1110 1100 1001 0001 0001 1111‘
Round 2 key:
Key2 =ATGC = '1011 0000 1110 1011 0011 0000 0000 0001 1010 0000 1110 1100
1001 0001 0001 1111 0011 0000 1001 0101 0011 1000 1010 0011 0011 0000 0011
1001 0100 1010 1100 0010 1010 1111 1111 0001 1001 1010 1000 1111 0011 1111
0100 1010 1010 0101 1111 1000 1100 1111 0000 0011 1010 1111 1000 1100 1100
1111 1010 1011 1100 0001 1111 0001'
20

step
Round 3 key:
Key3 = CATG = '1100 1111 0000 0011 1010 1111 1000 1100 1100 1111 1010 1011
1100 0001 1111 0001 1011 0000 1110 1011 0011 0000 0000 0001 1010 0000 1110
1100 1001 0001 0001 1111 0011 0000 1001 0101 0011 1000 1010 0011 0011 0000
0011 1001 0100 1010 1100 0010 1010 1111 1111 0001 1001 1010 1000 1111 0011
1111 0100 1010 1010 0101 1111 1000‘
Round 4 key:
Key4 = GCAT = '1010 1111 1111 0001 1001 1010 1000 1111 0011 1111 0100 1010
1010 0101 1111 1000 1100 1111 0000 0011 1010 1111 1000 1100 1100 1111 1010
1011 1100 0001 1111 0001 1011 0000 1110 1011 0011 0000 0000 0001 1010 0000
1110 1100 1001 0001 0001 1111 0011 0000 1001 0101 0011 1000 1010 0011 0011
0000 0011 1001 0100 1010 1100 0010'
21

Key Selection & Generation
Workflow
Figure 5. 4 Round Keys Generation Operation
22

Message Encryption Algorithmic step
Input: Input File; Round Keys.
Output: Cipher text
 Step 1: Read the byte values from the input file called plaintext and transform each
byte value into 8-bit binary representation.
 Step 2: Make 256-bit plaintext blocks from the binary representation.
 Step 3: Repeat step 4 and 11 for each block of plaintext.
 Step 4: Split the 256-bit block into four 64-bit blocks, namely P1, P2, P3, P4.
 Step 5: Subdivide each 64 bit Plain text parts into two 32 bit parts, namely P1L , P1R ,
P2L, P2R, P3L, P3R, P4L , P4R
 Step 6: Repeat step 7 and 10 for each Keyi, where 1 ≤ i ≤ 4.
 Step 7: Read the round encryption key and split into 64 bit parts, namely K1, K2, K3,
and K4.
 Step 8: Subdivide each 64 bit round key parts into two 32 bit parts, namely K1L , K1R ,
K2L, K2R, K3L, K3R, K4L , K4R
23

Message Encryption Algorithmic step
 Step 9: Compute four 64 bit parts of the Intermediate Cipher Text and store into 4
temporary variables:
temp1= Concate [(P1L ⊕ K1R), (P1R ⊕ K1L)]
 Step 10: Combine all 64-bit cipher blocks to form 256-bit Intermediate cipher text
block:
ICT = Concate(temp1,temp2,temp3,temp4)
 Step 11: Input ICT as input for the next round as plaintext.
 Step 12: Compute result of round 4 as final cipher text CT.
 Step 13: Club together all the 256-bit cipher text blocks.
24

Message Encryption Round operation
Figure 6. Encryption Operation for 4 Rounds
25

Message Encryption Rounds X-OR operation
Figure 7. Proposed EX-OR Operation
26

Message Encryption DNA Encoding
 Cipher text is converted into the DNA form of the data using Binary
to DNA substitution rule.
 Use WatsonCrick complementary rule of DNA.
 Primer selection from a public DNA database.(say NCBI).
 Padding extra information.
27

 Using the substitution rule: A=00, T=11, C=01 and G=10.
CT= 'TCTC TTGC AGGC CGAC GACT GTCG AATA TGTA TCAT
GCTT GACG
AACC ATTA CCCC CCGG TTCT CGAT GGAA ACAT TTTG CATT
CTTC GGCT
AGTG GCGG GAGA GGAA TATT TGTG ATTT ATTC GTGT‘
 Using the complementary rule: A T; T C; C G; G A→ → → →
CT= 'CGCG CCAG TAAG GATG ATGC ACGA TTCT CACT CGTC
AGCC ATGA TTGG TCCT GGGG GGAA CCGC GATC AATT
TGTC CCCA GTCC GCCG AAGC TACA AGAA ATAT AATT CTCC
CACA TCCC TCCG ACAC'
28

 Select a DNA sequence fromthe NCBI database:
DNAseq = ’TTCC CAAT AGGC TGGA CTGC TTAC CACC CCAT
GTGG CCTC AAAG AGCT CCAG TCAC TCCT TTAC GAAC
CCAA TCAC TCCA GAAC TTTA GAAC AAAG TTTC TGAG
TTAC TCCT TGTA ATAG GCTA AATA’ (say)
 Split DNAseq into 2 parts:
Starting primer = ’TTCC CAAT AGGC TGGA CTGC TTAC CACC
CCAT GTGG CCTC AAAG AGCT CCAG TCAC TCCT TTAC’
Ending primer = ’GAAC CCAA TCAC TCCA GAAC TTTA GAAC
AAAG TTTC TGAG TTAC TCCT TGTA ATAG GCTA AATA’
29

 After padding extra coding:
CT=TTCC CAAT AGGC TGGA CTGC TTAC CACC CCAT GTGG
CCTC AAAG AGCT CCAG TCAC TCCT TTAC CGCG CCAG
TAAG GATG ATGC ACGA TTCT CACT CGTC AGCC ATGA
TTGG TCCT GGGG GGAA CCGC GATC AATT TGTC CCCA
GTCC GCCG AAGC TACA AGAA ATAT AATT CTCC CACA
TCCC TCCG ACAC GAAC CCAA TCAC TCCA GAAC TTTA
GAAC AAAG TTTC TGAG TTAC TCCT TGTA ATAG GCTA
AATA
Figure 8. Basic format of the cipher DNA sequence
30

 Hash Mapping:
 CT is now mapped into a randomly selected array of 16 characters
using a hash mapping technique and form FCT.
Let, the randomly selected hash array be,
HA[16]=A, K, Z, S, J, B, T, M, L, F, P, C, R, Y,Q, O
 Each combination of DNA sequence is mapped into with the hash
function array (HA) by means of index values.
Table 2. Hash mapping array with DNA sequence
31

 Final Cipher Text (FCT) computation:
FCT=’BPLKSQMRFQBZLPPKYOPTASSFPSTZTFBZCCPSJSRMKQ
ZRBFLFCTSPKRBOTFOOOAPQRTABMTPLYPQCAQJLSAKKAB
FPLLTPTCZZRZPATZTLRZBJRZASBTMSBZTFMJKSQJAJ’
32

Message Encryption workflow
Figure 9. Schematic diagram of the overall
Message encoding method
33

Message Decoding workflow
Figure 10. Schematic diagram of the overall
Message decoding method
34

Ensuring Integrity
 Shared Hash function at both side.
 MD5 used as Hash function.
 Create Message Detection Code (MDC).
Figure 11. Message transmission ensuring
35

Key Analysis
36

Test Datasets
File Types File Size
(in KB)
Cipher Size
(in KB)
Encryption time
(in ms)
Decryption Time
(in ms)
.doc 147 588 6833 4846
.pdf 384 1536 11466 8050
.jpg 768 3072 39431 22371
.mp3 3105 12420 62712 28314
.flv 4028 16112 78717 34804
37
Table 2. Test Datasets with attributes

Length Analysis
CSE Dept. SSCET, Badhani Figure 12. Length Analysis
38 FileSizeinKB
File Type

Time Analysis
CSE Dept. SSCET, Badhani Figure 12. Time Analysis
39 TimeinMilliseconds
File Type

Strength of Proposed Approach
 Enhanced security:
 Long 256 bit encryption key– Difficult to brute force attacks
 Improved DNA base encryption – Provide ambiguity
 Use of Message Detection Code – Ensuring integrity
40

Conclusion
 Since there are large number of DNA
sequences are available it is almost
impossible to predict which sequence has
been used for encryption.
 Intruders will not be able to predict the main
cipher text for cryptanalysis due to the
presence of extra information along with the
main cipher.
41

Future Scope
 Implementation of signature, steganography.
 This improved concept can be used in the
security concerned of real time security of
distributed network systems.
42

Reference
43
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