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DNA Computers Applications:DNA Computers Applications:
CryptographyCryptography
Constanza Lampasona
Innovative Computer Architectures and Concepts
Computer Architecture Department - University of Stuttgart
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June 2002 DNA Computers Applications: Cryptography 2
MotivationMotivation
SiliconSilicon technologies have limitslimits
Research intends to deal with ³silicon´ disadvantagesdeal with ³silicon´ disadvantages
DNA computingDNA computing -> inherent parallelisminherent parallelism
Cryptographic problemCryptographic problem requires vast parallelism
Let¶s solve the cryptographic problem using a molecular computer!!!Let¶s solve the cryptographic problem using a molecular computer!!!
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June 2002 DNA Computers Applications: Cryptography 3
OutlineOutline1. Introduction
2. Cryptography
3. DNA Computing
4. Breaking DES using a molecular computer
5. Conclusions
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June 2002 DNA Computers Applications: Cryptography 4
IntroductionIntroduction Encoding data ³as in nature´
Recombination
algorithmInput Output
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June 2002 DNA Computers Applications: Cryptography 5
IntroductionIntroduction Cryptography
Gjoe joh uif lfz Shift by oneShift by one Finding the key
Secret writing
Data Encryptation Standard: approved c ryptographi c algorithmc ryptographi c algorithm as
required by FIPS 140-1 (Federal Information Processing Standards)
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June 2002 DNA Computers Applications: Cryptography 6
OutlineOutline1. Introduction
2. Cryptography
3. DNA Computing
4. Breaking DES using a molecular computer
5. Conclusions
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June 2002 DNA Computers Applications: Cryptography 7
CryptographyCryptography
³The art of writing wit h a secret key secret key or in an enigmatic way´
From the Greek: cryptocrypto--,, hidden + --graphy graphy , writing
Let¶s look at history...
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June 2002 DNA Computers Applications: Cryptography 8
CryptographyCryptography Encryption
Protecting information
Ensure privacyprivacy
Keep the information hiddeninformation hidden
Data Transformation Unreadable form
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June 2002 DNA Computers Applications: Cryptography 9
CryptographyCryptography Decryption
Reverse of Encryption
Encrypted data Transformation Intelligible form
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June 2002 DNA Computers Applications: Cryptography 10
CryptographyCryptography
Encryption Decryption
Secret KEY
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June 2002 DNA Computers Applications: Cryptography 11
CryptographyCryptographyEncrypted data (cipher-text): Khoor zruog
Secret KEY: shift by 3
Decrypted data (plain-text): Hello world
a b c d e f g h i j k l m n o p q r s t u v w x y z
d e f g h i j k l m n o p q r s t u v w x y z a b c
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June 2002 DNA Computers Applications: Cryptography 12
CryptographyCryptography Data Encryption Standard (DES)
Crytographic algorithm (National Bureau of Standards).
E nciphering E nciphering and Deciphering Deciphering.
64-bit key.
Data depends on key¶s security.
Unique keyUnique key for encryting and decryting.
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June 2002 DNA Computers Applications: Cryptography 13
CryptographyCryptography DES¶ Data Encryption Algorithm
E nc iphering
Initial
permutation
IP
ComputationInverse initial
permutation
IP -1
Input Output
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June 2002 DNA Computers Applications: Cryptography 14
CryptographyCryptographyInitial
permutation
IP
ComputationInverse initial
permutation
IP -1
Input Output
IP
58 50 42 34 26 18 10 2
60 52 44 36 28 20 12 4
62 54 46 38 30 22 14 6
64 56 48 40 32 24 16 8
57 49 41 33 25 17 9 159 51 43 35 27 19 11 3
61 53 45 37 29 21 13 5
63 55 47 39 31 23 15 7
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June 2002 DNA Computers Applications: Cryptography 15
CryptographyCryptographyInitial
permutation
IP
ComputationInverse initial
permutation
IP -1
Input Output
Uses the permuted input block as input.
Produces a pre-output block.
16 iterations.
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June 2002 DNA Computers Applications: Cryptography 16
CryptographyCryptographyInitial
permutation
IP
ComputationInverse initial
permutation
IP -1
Input Output
IP-1
40 8 48 16 56 24 64 32
39 7 47 15 55 23 63 31
38 6 46 14 54 22 62 30
37 5 45 13 53 21 61 29
36 4 44 12 52 20 60 2835 3 43 11 51 19 59 27
34 2 42 10 50 18 58 26
33 1 41 9 49 17 57 25
Plain-text Cipher-text
Key
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June 2002 DNA Computers Applications: Cryptography 17
OutlineOutline1. Introduction
2. Cryptography
3. DNA Computing
4. Breaking DES using a molecular computer
5. Conclusions
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June 2002 DNA Computers Applications: Cryptography 18
DNA ComputingDNA Computing
DNADNA(Deoxyribonucleic acid) GeneticGenetic information ³memory´
NucleotidesNucleotides strung into
polymer chainspolymer chains (DNA Strands)
Four classes of nucleotides:
Adenine, Guanine, Cytosine, Thymine Adenine, Guanine, Cytosine, Thymine (A,C,G,T)
DNA
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June 2002 DNA Computers Applications: Cryptography 19
DNA ComputingDNA Computing The Structure of DNA
The double helix structure discovered by Watson and Crick
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June 2002 DNA Computers Applications: Cryptography 20
DNA ComputingDNA Computing
Based on Adleman¶sAdleman¶s work (1994)
Solve huge problemshuge problems by parallel search
Much faster Much faster than a conventional computer
More hardwareMore hardware vs. more DNA
DNADNA
Computer:Computer:
DNA Strands
+
Combinations
=
³Solution´
DNADNA
Computer:Computer:
DNA Strands
+
Combinations
=
³Solution´
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June 2002 DNA Computers Applications: Cryptography 21
OutlineOutline1. Introduction
2. Cryptography
3. DNA Computing
4. Breaking DES using a molecular computer
5. Conclusions
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June 2002 DNA Computers Applications: Cryptography 22
Breaking DESBreaking DES
FindingFinding aa keykey given one pair one pair (plain-text, cipher-text).
PrePre--processingprocessing + one day of workone day of work = recover the key.
First exampleFirst example of a real problem solved using DNA.
The Idea
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June 2002 DNA Computers Applications: Cryptography 23
Breaking DESBreaking DES
Generate all possible solutions in parallelGenerate all possible solutions in parallel
Remove wrong solutionsRemove wrong solutions
Massive parallel DNA computing approach:
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June 2002 DNA Computers Applications: Cryptography 24
Breaking DESBreaking DES
Representing binary stringsRepresenting binary strings
Plan of DES attackPlan of DES attack
Prepare the DNA solutionPrepare the DNA solution
Extract desired patternsExtract desired patterns
Read the resultRead the result
Break DES!!!Break DES!!!
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June 2002 DNA Computers Applications: Cryptography 25
Breaking DESBreaking DES
DES(M0,k) encoding plain-text with all possible 256 keys
4 months
Extract DES(M0,k)=E0, (plaintext, cipher-text)
Read k
1 day
Summary of the experiment
DNA Computer:DNA Computer:
DNA Strands+
Combinations
=
³Solution´
DNA Computer:DNA Computer:
DNA Strands+
Combinations
=
³Solution´
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June 2002 DNA Computers Applications: Cryptography 26
OutlineOutline1. Introduction
2. Cryptography
3. DNA Computing
4. Breaking DES using a molecular computer
5. Conclusions
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June 2002 DNA Computers Applications: Cryptography 27
ConclusionsConclusions DNA computing with a concrete application,
Cryptography
Very general attack on DES, using 64-bit key
Cryptosystems with 64-bit key are insecure
Future of molecular computers: Unclear
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June 2002 DNA Computers Applications: Cryptography 28
SummarySummary
Cryptography
DES
DNA Computing >>> Parallelism
Breaking DES