There are several different approaches for using deoxyribonucleic acid (DNA) to make chips hacker-proof.
One approach, which isn’t really adding anything to the chip but does come under the DNA heading, is using the natural tolerance limits of chip manufacturing that occurs across wafers. There are minute variations on the offset layer that stratifies the wafer, which can affect the power signature of chips on the wafer.
A second approach is physically inclinable functions, or PUF, which uses the unique signature DNA of chip identification. This works because PUF can be used to generate an unpredictable but repeatable response from the stimulus.
On other fronts, there have been some significant strides made in marking chips with plant DNA that makes them impossible (for now) to clone or counterfeit. One rather novel method fixes plant-generated DNA markers onto the chips. The advantage of this approach is that it can be done to just about any chip, and not necessary as part of the chip fabric or electronic layers. And, it works with most standard chip-marking equipment, so there are no added costs.
There are some bleeding-edge solutions on the drawing board, as well, that promise to offer a more real DNA-type methodology. This is based on bimolecular computing implementing some processes that are used in DNA computing; extreme information density, and massive parallelism.
DNA computing is a methodology that uses molecular biology to simulate the bimolecular structure of DNA and computing. There is currently some new work going on in the area of DNA computing that focuses on cryptography. It is an elegant theory of using DNA and amino-acid encoding to turn encryption schemes into virtually unbreakable platforms.
There are some rather ingenious methodologies that have been proposed on ways accomplish this. (See references 2, 3 and 4 a the end of this article.) For this discussion, we will look at using a one-time pad (OTP) encryption technique and applying DNA coding to make it even more secure.
Theoretically, an OTP cipher is an unbreakable cryptosystem. However, that is only true if certain conditions are met for each cypher. They are:
- It must be truly random.
- It can never be re-used.
- It must be kept secret.
However, in reality there are some issues with this, most of which deal with storing and auditing such keys. Therefore, by implementing DNA and amino acid coding, downsides can be eliminated.
The following is an abbreviated overview of a method proposed in a paper by professors out of Behna University in Egypt ). It is probably the most recent iteration of such a theory.
Essentially, it takes the standard binary code of 1s and 0s and applies it to convert the target code to a DNA sequence. It uses the four different bases found in a DNA sequence; Adenine (A) and Thymine (T), or Cytosine (C) and Guanine (G). These four bases, using binary 1s and 0s, can be encoded in the following way: 0 = A(00); 1 = C(01); 2 = G(10); 3 = T(11).
This binary coding scheme is then used to convert the target code or message to a DNA sequence. Then this DNA sequence is converted to the amino acid form. There are 64 possible 3-letter combinations of the DNA coding units T, C, A and G, which are used either to encode one of these amino acids, or as one of the three stop codons that signals the end of a sequence. Once the encoding is done, the data can be sent over any unsecured medium (refer to the paper for a precise explanation of the process and encryption/decryption algorithms).
From the outside, it would seem that it is not that difficult to decode the DNA sequence if one knows its protein source. However, because most amino acids have multiple codons, finding the correct sequence is virtually impossible because there are too many DNA sequences that could represent the same protein sequence. So unless both the sender and receiver have the same key, the data cannot be decoded correctly.
There are similar DNA methods being proposed that are lower on the food chain. There also is a proposed methodology that consists of a hybrid cryptographic protocol based on DNA technology which applies a DNA chip (microarray) with DNA probes to encrypt and decrypt sensitive information.