DNA Lock™ Counterfeit-Resistant Authentication
Carter Bancroft, Ph.D., Mount Sinai School of Medicine, NY

• Background: “DNA-Based Steganography”
  [Clelland, Risca, Bancroft. Hiding Messages in DNA Microdots. Nature (1999) 399:533-534]
  
  
• Summary: We have extended our DNA-based steganography concept to the development of a secure authentication technique. DNA Lock ™ yields a highly concealed DNA-encoded authentication code that can be detected and read only by authorized personnel, and is thus highly counterfeit-resistant.
  

Properties of DNA as a Technological Tool

• DNA is the central repository of information in the cell.
  
  
• DNA stores information efficiently. Four different bases (A, T, G, and C) imply 4^n possible different n-mers.
  
  
• A large number of elements (DNA strands) occupies a small space: 10^12 strands in about 100ul (1/10th of a marble).
  
  
• Hybridization between two DNA strands is strongly sequence- specific. Only complementary strands will hybridize:
  

Approach by Bancroft Group to Development of DNA-Based Technologies

• Definition: DNA-Based Technologies are non-biological technologies that employ the biological polymer DNA.
  
  
• Summary: We are developing DNA-based technologies that are based upon:
  - The biochemical properties of DNA, and its enzymes.
  - The techniques of molecular biology that we employ in our biomedical research.
  
  
• Technique Examples: PCR, DNA microarrays (microchips).

DNA-Based Steganography

• Background: Most current cryptosystems (e.g., RSA) are based upon factorization problems, and are thus vulnerable to attack by powerful (ultimately quantum?) computation.
  
  
• Summary: We have developed “DNA-Based Steganography”- a method for camouflaging a DNA-encoded message within the enormous complexity of the human genome.
  
  We believe that “breaking” DNA-based steganography would represent an intractable biochemical problem. This technique is thus strongly resistant to either computational or biochemical attacks.

DNA Lock™

Counterfeit-resistant identification of

• Labels, packaging, or documents.
  
• Solid objects (e.g., industrial parts).
  
• Liquids (e.g., ink, perfume, forensic samples).

DNA Lock™ Summary and Considerations

• Authentication DNA Code highly concealed: Ratio of Concealing DNA/Authentication Code DNA = 30 million. This makes detection and counterfeiting of Authentication Code DNA extremely difficult.
  
  
• Concealing DNA can be from any organism(s) in the world.
  
  
• Enormous number of different DNA codes:
  Number of different codes = n4 (where n= # DNA bases in the Authentication Code sequence).
  
  -10 bases of code yields 410 ~ one million different codes.
  
  -20 bases of code yields 420 ~ one trillion different codes.
  


• Readout: Requires biochemical analysis (PCR, plus DNA sequence analysis), implying no hand-held reader (at present).
  
  
• Proof-of-principle, and publicity: Underlying technology published 1999 in Nature (“Hiding Messages in DNA Microdots”, 399:533).
  
  - Paper received extensive publicity: multiple newspapers worldwide (including NY Times Science section), websites, plus Bancroft interviews on radio (BBC) and TV (Tokyo).
  
  - Resulting patent subject of NY Times article, 1/14/02.
  
  
• Patent status: U.S. Patent #6,312,911 “DNA-based steganography”, issued to Bancroft and Clelland, November 6, 2001.

DNA Microarrays: Potential Utility with DNA Lock™

1. Current Use of DNA Microarrays in Biology
DNA Microarray = Ordered Array of Thousands of DNA Samples.

Current Use in Biology: Gene Expression Patterns (“Signatures”).

• A robot spots up to 10,000 DNA samples (~100x100 matrix) onto a 2cm^2 array on glass or filter.
  
  
• The array is hybridized with colored cellular RNA probe(s) (simultaneous use of two or more probes increases efficiency).

DNA Microarrays: Potential Utility with DNA Lock™

2. Potential Extension of DNA Lock™ to Authentication Tags Containing DNA Microarrays

• Microarray can be formed on removable filter (or directly on plastic support).
  
  
• All spots contain concealing DNA; only a pattern of spots contains authentication code DNA.

1. Remove filter tag from support, attach to authenticated item.
   
   
2. Authentication (Level 1): Determine whether analysis (primer extension) with specific primer yields expected spot pattern. [Spot pattern could represent a binary code (#’s written as 0 or 1).]
   
   
3. Authentication (Level 2): Determine whether DNA product contains the correct authentication code sequence.

• “DNA-Based Steganography”, a technique for hiding messages in genomic DNA, that is resistant to either computational or biochemical attack.
  
  
• DNA Lock™ (derived from DNA-Based Steganography), for counterfeit-resistant authentication of valuable objects.