The use of DNA as a unique piece of evidence did not start until 1984, by a scientist known as Alec Jeffreys. It did not make its mark in the United States until at least the late 1980’s, when the FBI invested many resources in exploring the use of DNA as a form of criminal evidence which could be presented in a court of law.
As a result of this massive effort, one of the world’s largest databases was born. Today it is known as the Combined DNA System, or CODIS for short. This database is now used by law enforcement agencies at all levels throughout the United States, as well as internationally. By 2012, CODIS held the DNA records of more than 1.2 million individuals, primarily those of criminals, suspects, and illegal immigrants.
At the present time, DNA is only used for forensic purposes, often collected as a means of latent evidence. It can only be used for identification purposes, not for verification applications, due to the time (four to five hours) required to process the raw data that is collected.
But due to the uniqueness and richness of the data that DNA possesses, there is a strong interest in using it as a potential biometric technology. The use of DNA makes strict use of the patterns which are found in deoxyribonucleic acid, which is located in the cell nucleus of all living beings, no matter how large or how small.
DNA Recognition: How It Works
DNA profiling makes use of the common, repetitive patterns of the four base pairs, which are Adenine (A), Cytosine (C), Guanine (G), and Thymine (T). It should be noted that DNA profiling occurs in the uncoded portion of the DNA sequence, which is simply known as the uncoded DNA, for which there is no identified function. A base pair pattern can look like this: AGCCTTCAGTA.
This sequence is also known as a Short Tandem Repeat, or an STR for short. A unique STR exists when two or more base pairs appear in a certain and repetitive pattern, and also when this exact pattern is repeated close by in adjacent spots. It should be noted that the STR is typically anywhere from two to four nucleotide base letters, and even larger patterns, known as Variable Number Tandem Repeats, or VNTR for short, can contain up to eighty letters. This thus provides for a much higher degree of accuracy and probability. But this analysis can take up to days to complete, not just a matter of a few short hours.
There are two kinds of DNA which are currently present in all living beings:
- Nuclear DNA: This is the contribution of genetic components from both the mother and the father, and is most commonly found in the blood, saliva, semen, and even the bones.
- Mitochondrial DNA: This is the contribution of genetic components from the mother only, and it can also be found in the hair and the teeth. This is the type of DNA which is used to identify missing individuals.
The raw DNA sample can be collected from blood, semen stains, saliva, hair, or even under voluntary conditions. With the latter approach, a buccal swab can be very easily inserted into the mouth, in order to collect a sample of DNA. After the DNA sample is collected from the specific source, the DNA is then isolated, and then further divided into much shorter segments (known as restriction enzymes) which terminate the DNA strands at various points and differentiated in size using an electric current.
The differentiated sizes are then placed onto a nitrocellulose filter which possesses different fluorescent dyes, which then further attach themselves to the differing repeating patterns. This is then X-rayed, and the resulting image is a DNA “fingerprint.” An image of a DNA strand can be seen in Figure 1, below.
Figure 1: Magnified image of a DNA strand
Subsequently, this DNA fingerprint is translated into a DNA profile which displays the number of STR’s at the specific locations. The DNA markers used to construct this DNA profile are located on chromosome numbers 1, 2, 4, 5, 10, and 17. These specific locations are referred to as DNA loci. After this profile is constructed, the findings occur in one of the following three categories:
- Exclusion: This result possesses the highest level of certainty, i.e., the raw data is different from the source it was collected from.
- Non-Exclusion: The raw data cannot be excluded as coming from the same source, i.e., the raw DNA sample and the source from which it was collected are similar but not identical.
- No Result: No conclusions can be drawn.
DNA Recognition Technology: Advantages & Disadvantages
Because DNA recognition technology is still undergoing heavy research and development, it can only be matched up against five of the seven criteria, which are as follows:
- Uniqueness: Amongst all of the other biometrics, DNA possesses the most unique and richest information and data (even more so than the retina), and if it proves to be a viable biometric technology, it will far surpass the levels of the other biometrics which currently exist in the marketplace.
- Collectability: The right quality and quantity of DNA must be present, and the material must not be contaminated.
- Performance: DNA analysis is very useful and robust for forensic applications, but it is not yet useful for verification purposes. The four to five hours of analysis currently required to process a DNA sample will need to be reduced to a matter of seconds for verification applications.
- Acceptability: DNA is very much prone to privacy rights issues, and while the DNA profile itself possesses genetic information about an individual, the raw DNA data does not.
- Resistance to Circumvention: DNA is rich in terms of unique data and information, so it cannot be substituted for another person’s DNA.
Other disadvantages of DNA recognition include:
- DNA samples are prone to degradation and contamination.
- Implementing the security protocols for a DNA-based biometric system could prove exceptionally complex. This applies to database protection and overall system confidentiality in equal measure.
Up Next: Our next article will examine another biometric technology of the future: Gait Recognition.
Ravi Das is a Cybersecurity Consultant and Business Development Specialist. He also does Cybersecurity Consulting through his private practice, RaviDas Tech, Inc. He also possesses the Certified in Cybersecurity (CC) cert from the ISC2.