DNA Based Steganography

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DNA Based Steganography

NOMAN ISLAM

National University of Computer and Emerging National University of Computer and Emerging Sciences, Karachi

Sciences, Karachi

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Outline

 Preliminaries and traditional Approaches to Preliminaries and traditional Approaches to

Steganography Steganography

 Polymerase Chain ReactionPolymerase Chain Reaction

 DNA based SteganographyDNA based Steganography

 Relevant WorkRelevant Work

 ConclusionConclusion

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Preliminaries

 Two principal ways to keep a message out of the Two principal ways to keep a message out of the enemy’s hands:

enemy’s hands:

 Conceal the message and hope that the enemy can’t find Conceal the message and hope that the enemy can’t find

it (

it (Steganography)Steganography)

 Scramble the message, and hope that if it is intercepted) Scramble the message, and hope that if it is intercepted)

the enemy is unable to unscramble it (

the enemy is unable to unscramble it (CryptographyCryptography))  Stegano means covered/secret and graphy means Stegano means covered/secret and graphy means

drawing drawing

 It is the art and science of writing hidden messages in It is the art and science of writing hidden messages in

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Preliminaries

 Steganalysis is the detection of Steganalysis is the detection of

steganography by a third party. This can steganography by a third party. This can

be done by various mean like statistical be done by various mean like statistical

and structural analysis of carrier and structural analysis of carrier

 Payload is the desired data to be transport Payload is the desired data to be transport

 Carrier is the signal, stream, or data file Carrier is the signal, stream, or data file

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Steganography Approaches

 Shaving the head of messenger and putting message Shaving the head of messenger and putting message on it

on it

 Carving the messages on wood of wax tabletsCarving the messages on wood of wax tablets  Invisible Inks Invisible Inks

 (Phenolphthalein, a pH indicator that turns pink in the (Phenolphthalein, a pH indicator that turns pink in the

presence of a base such as ammonia presence of a base such as ammonia

 other sources include lemon juices, milk etcother sources include lemon juices, milk etc

 Microdots (developed by Professor Zapp, used in Microdots (developed by Professor Zapp, used in world war II by Germans)

world war II by Germans)

 complete documents, pictures, and plans reduced in size complete documents, pictures, and plans reduced in size

to the size of a period and attached to common to the size of a period and attached to common

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Steganography Approaches

 Null Ciphers (used in World War II by germans)Null Ciphers (used in World War II by germans)

 unencrypted messages with real messages embedded in the unencrypted messages with real messages embedded in the

current text. For example, consider the message: current text. For example, consider the message:

Fishing freshwater bends and saltwater coasts Fishing freshwater bends and saltwater coasts rewards anyone feeling stressed. Resourceful anglers

rewards anyone feeling stressed. Resourceful anglers

usually find masterful leapers fun and admit

swordfish rank overwhelming any day

By taking the third letter in each word the following message By taking the third letter in each word the following message

emerges: emerges:

Send Lawyers, Guns, and Money

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An Example from Modern

Practice

By removing all but the last 2 bits of each colour component, an almost completely black image results. Making the resulting image 85 times brighter

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Polymerase Chain Reaction

(PCR)

 The PCR (developed by Kary Mullins who The PCR (developed by Kary Mullins who got Nobel prize in 1993) mimics the DNA

got Nobel prize in 1993) mimics the DNA

copying mechanism in an artificial manner

 This process is done in a tube under suitable This process is done in a tube under suitable temperature and provides a quick means of

temperature and provides a quick means of

selectively amplifying small quantities of

DNA

 It has found applications in Forensic It has found applications in Forensic Analysis and Steganography

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PCR Requirements

 PCR Vial requires following for DNA replication:PCR Vial requires following for DNA replication:

 A piece of DNAA piece of DNA

 Large quantities of four nucleotide (A,T,C,G)Large quantities of four nucleotide (A,T,C,G)  Primer SequencesPrimer Sequences

 Two small pieces of synthetic DNA, each complementing a Two small pieces of synthetic DNA, each complementing a

specific sequence at one end of the target sequence, serve as specific sequence at one end of the target sequence, serve as primers. Each primer binds to its complementary sequence. primers. Each primer binds to its complementary sequence. Polymerases start at each primer and copy the sequence of Polymerases start at each primer and copy the sequence of that strand.

that strand.

 DNA polymerase DNA polymerase

 usually Thermus Aquaticus (Taq) polymeraseusually Thermus Aquaticus (Taq) polymerase

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PCR Process

 DenaturationDenaturation

 This phase separates the two DNA chains in the This phase separates the two DNA chains in the

double helix. This is done simply by heating the vial

to 90-95 degrees centigrade (about 165 degrees

Fahrenheit) for 30 seconds

 Primer AnnealingPrimer Annealing

 But the primers cannot bind to the DNA strands at But the primers cannot bind to the DNA strands at

such a high temperature, so the vial is cooled to 55

decrees C (about 100 degrees F). At this

temperature, the primers bind or "anneal" to the

ends of the DNA strands. This takes about 20

seconds

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PCR Process

 Primer ExtensionPrimer Extension

 The final step of the reaction is to make a complete copy of The final step of the reaction is to make a complete copy of

the templates. Since the Taq polymerase works best at the templates. Since the Taq polymerase works best at

around 75 degrees C (the temperature of the hot springs around 75 degrees C (the temperature of the hot springs

where the bacterium was discovered), the temperature of the where the bacterium was discovered), the temperature of the

vial is raised. The Taq polymerase begins adding nucleotides vial is raised. The Taq polymerase begins adding nucleotides

to the primer and eventually makes a complementary copy of to the primer and eventually makes a complementary copy of

the template. If the template contains an A nucleotide, the the template. If the template contains an A nucleotide, the

enzyme adds on a T nucleotide to the primer. If the template enzyme adds on a T nucleotide to the primer. If the template

contains a G, it adds a C to the new chain, and so on to the contains a G, it adds a C to the new chain, and so on to the

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PCR Process

 This completes one PCR cycleThis completes one PCR cycle

 The three process takes less than 2 minutesThe three process takes less than 2 minutes

 At the end of a cycle, each piece of DNA in the At the end of a cycle, each piece of DNA in the

vial has been duplicated. vial has been duplicated.

 If the cycle is repeated 30 or more times, each If the cycle is repeated 30 or more times, each

newly synthesized DNA piece can act as a new newly synthesized DNA piece can act as a new

template, so after 30 cycles, 1 billion copies of a template, so after 30 cycles, 1 billion copies of a

single piece of DNA can be produced. single piece of DNA can be produced.

 Taking into account the time it takes to change Taking into account the time it takes to change

the temperature of the reaction vial, 1 million the temperature of the reaction vial, 1 million

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DNA based Steganography

 Idea was developed by Taylor Clelland at Mount Idea was developed by Taylor Clelland at Mount

Sinai School of Medicine in New York Sinai School of Medicine in New York

 The researches first perform a simple encryption The researches first perform a simple encryption

technique to encode a message in the form of technique to encode a message in the form of

DNA bases DNA bases

 The message is then hid among billions of other The message is then hid among billions of other

similar DNA strands similar DNA strands

 Only an intended recipient (who has the key: Only an intended recipient (who has the key:

primer sequences) could isolate and read from primer sequences) could isolate and read from

millions of similar strands by applying PCR millions of similar strands by applying PCR

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DNA Based Steganography – Basic

Steps

 Assign 3-base units to letters of the alphabet, Assign 3-base units to letters of the alphabet,

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Steps

 The message sequence is then The message sequence is then

sandwiched between two carefully sandwiched between two carefully

selected oligonucleotide units -primers selected oligonucleotide units -primers

(consisting of 20 bases each in the original (consisting of 20 bases each in the original

experiment), known only to the sender experiment), known only to the sender

and the intended recipient and the intended recipient

 The DNA message is like a dot and can be The DNA message is like a dot and can be

taped over in a period in a typed letter taped over in a period in a typed letter

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DNA Based Steganography – Basic

Steps

 Only a recipient knowing the sequences of both Only a recipient knowing the sequences of both

primers would be able to extract the message, primers would be able to extract the message, using the polymerase chain reaction (PCR) to using the polymerase chain reaction (PCR) to

isolate and make copies of (amplify) the isolate and make copies of (amplify) the message-containing DNA strand. It would then be a simple containing DNA strand. It would then be a simple matter to determine the sequence of nucleotides in matter to determine the sequence of nucleotides in the relevant strand and decode the message. In the relevant strand and decode the message. In contrast, an eavesdropper would have to undertake contrast, an eavesdropper would have to undertake the virtually impossible task of sifting through 4^20 the virtually impossible task of sifting through 4^20

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How Secure is this?

 First, the message itself is concealed in a First, the message itself is concealed in a

microdot, very rare that some one figure out

that

 The secret message is masked by enormous The secret message is masked by enormous complexity of DNA in which it is contained.

complexity of DNA in which it is contained.

If the primer is 20 bases long, there are

4^20 possibilities

 The original message is also encoded in The original message is also encoded in triplets (so there are 4*4*4 possibilities)

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How Secure is this?

 How ever [4] has analyzed the method How ever [4] has analyzed the method

and developed a statistical method to and developed a statistical method to

detect regions of DNA which are different detect regions of DNA which are different

from its background to warrant further from its background to warrant further

investigations investigations

 A signature graph is drawn to find out A signature graph is drawn to find out

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Relevant Work

 [1] has extended this basic technique of DNA [1] has extended this basic technique of DNA

based steganography based steganography

 They developed algorithms for DNA based They developed algorithms for DNA based

cryptography by employing: cryptography by employing:

 One Time Pad Cipher for AdditionOne Time Pad Cipher for Addition

 One Time Pad Cipher for XOR operationOne Time Pad Cipher for XOR operation

 Since, using DNA bases, a truly random one time Since, using DNA bases, a truly random one time

pad can be developed, hence they claimed their pad can be developed, hence they claimed their

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Conclusion

 In short DNA is very useful in computational In short DNA is very useful in computational

algorithm because of algorithm because of

 its massively parallel operationits massively parallel operation

 ultra scale storage - ultra scale storage - A gram of DNA contains A gram of DNA contains

10^21 DNA bases = 10^21 tera-bytes 10^21 DNA bases = 10^21 tera-bytes

 fast replicationfast replication

 easy to hide – needle in a haystackeasy to hide – needle in a haystack

 Steganography along with ultra-scale storage Steganography along with ultra-scale storage

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every-I believe things like DNA

I believe things like DNA

computing will eventually

lead the way to a “molecular

revolution,” which ultimately

will have a very dramatic

effect on the world. – L.

Adleman

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References

1.

1. ‘‘DNA-Based Cryptography’, Ashish Gehani, Thomas DNA-Based Cryptography’, Ashish Gehani, Thomas

LaBean, and John Reif

2.

2. ‘‘Cryptography with DNA binary strands’, Ande Leier, Cryptography with DNA binary strands’, Ande Leier,

Christoph Richter, Wolfgang, Hilmar, December 1999

3.

3. ‘‘Hiding Messages in DNA Microdots’, NATURE 399 Hiding Messages in DNA Microdots’, NATURE 399

(1999):533-534

4.

4. ‘‘Finding Secret Messages in DNA Microdots’, Stephen Finding Secret Messages in DNA Microdots’, Stephen

A. Jarvis, Jason S. Mirsky, John F. Peden and Nigal J.

Saunders, September, 2000

5.

5. ‘‘DNA Based Steganography for Security Marking’, DNA Based Steganography for Security Marking’,

Wendell M. Smith, Technology Transfer Group , XIX

INTERNATIONAL SECURITY PRINTERS’ CONFERENCE

Montreux, 14-16 May 2003