Today, every message that we send online, every transaction that we carry out online using classical computers. It is highly encrypted. It means that the messages and the transactions being sent between two parties are highly safe and secure, and it cannot be easily intercepted by a third party. In the world of classical computers. Only those who possess the encryption key, only they can access the messages and the transactions that are going on online. In classical computing, the security of messages has been ensured by various encryption techniques such as integer factorization and other mathematical models that have been developed or the discrete logarithm problem. We should have a basic idea that these are the kind of encryption techniques which are used to keep all computer transactions transaction safe and secure in the classical computing domain. These encryption keys cannot be cracked or predicted by other classical computers, because the calculations are so complex that it might take years, or maybe decades or even centuries for a classical computer to crack these complex mathematical problems. However, the emergence of quantum computing has directly challenged traditional encryption, which is used in all classical computers. So to understand this, we need to understand the basic difference between classical computing, and quantum computing.

Classical computer functions in the binary format, at the lowest level of the computer language transactions, are carried out in bits, and each bit can either occupy zero or one as a binary state at any given point of time. So for example, if we take a two-bit computer. These are the four different states that the computer can occupy, but binary computing doesn't allow for these states to be occupied simultaneously at any given point of time, the binary bits can be either 00 or 01 or 10 or 11. So this significantly slows down the speed of computing, with classical computers. Even if you build supercomputers, they still carry out transactions in the binary state with very high levels of encryption. It becomes almost impossible for classical computers, even for supercomputers to crack these encryption keys. We know classical computers, including supercomputers might take years or even decades to crack these complex mathematical problems. However, the emergence of quantum computing marks a paradigm shift in the way computing is done. As the name itself indicates what computers exist in the quantum state. Here, instead of bits, we have something known as cubits, and they can simultaneously occupy the position of zero and one. So basically, quantum computing provides for the superposition of states, two different states can exist simultaneously and this exponentially increases the computing power of the system. So this allows for parallel computing to be carried out, and thereby quantum computers have the potential to crack these encryption keys that were primarily designed for classical computers.

Hence, the emergence of quantum computers is seen as a threat to traditional encryption. And this has created the need for a new type of encryption, that has been developed under quantum cryptography, and as well as under post-quantum cryptography. These are two emerging domains in the field of quantum computing, and it is seeking to develop strong encryption techniques and methods which will make it difficult even for quantum computers to crack. Currently, experts are looking at a concept known as lattice structure to design the encryption keys, because when a lattice structure is adopted into a mathematical model and based on this if an encryption key is designed, then it might become impossible, even for quantum computers to crack the encryption keys. See a lattice structure is nothing but a series of points that are arranged regularly in space in one dimension. It could just be a series of regularly spaced points in three dimensions. It could be the honeycomb structure, which is a hexagon structure. It could also be the crystalline structure of salt, which is essentially a lattice structure. So when this lattice structure is adopted into a mathematical model. And based on this, if encryption keys are developed, then those encryption keys cannot be cracked, even by quantum computers. So currently, this is the focus area of research in the field of quantum cryptography and post-quantum cryptography.

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