Ever wondered if the transactions, communications, information transfer that happens over the internet is secure or not? Is it hackable? The answer is yes, and to avoid that we use the concept of cryptography. In simple terms, cryptography is a technique of secure communication with the method of converting plain text from the sender into unreadable text or encoded message using a key or a cipher. When the intended receiver receives this encoded message, he has the key to decode it, and hence the transfer of information is protected in this case.
Having understood the concept of cryptography let us understand what quantum cryptography is.
As we discussed above, cryptography was the method of encrypting the data with a key and decoding it at the receiving end to protect it from attacks of cybercrimes. With the same logic, let us try and define quantum cryptography- if the technique used to encrypt the plaintext is the principle of quantum mechanics then it is called quantum cryptography. It takes advantage of the ‘no change theory’ that means it cannot be interrupted knowingly or unknowingly. As we know, as per the definition of quantum in physics is a packet of energy. Also, an important thing to note here is that it is different from post-quantum cryptography.
While it sounds simple, the complexity lies in understanding the principles of quantum mechanics which are used in this technique:
As per the definition of quantum cryptography, it uses the principles of quantum mechanics and quantum algorithms to make it technically unhackable. Let us consider a transfer of data between two parties i.e. sender and receiver. In quantum cryptography, the key used to cipher the plaintext is called quantum key distribution (QKD) i.e. a sequence of photons to transmit the data over an optical fiber cable. By comparing measurements of the properties of these photons, the parties involved will be able to find out what the key is and if it is compromised by any third party.
Let us dive deeper into understanding a step-by-step breakdown of the process and understand quantum cryptography basics:
This ensures the safety and confidentiality of information transmitted as the hacking or intercepting will be discarded in the communication medium itself. The photons that are compromised by the eavesdropper will change their state. The change can be noticed at the endpoint which makes it easier for detection and removal.
This is how encryption works- a sequence of binary digits is shared from one end then it is deciphered at the other end by either using a private or public key.
Symmetric cryptography is tougher to break compared to asymmetric cryptography. Let us have a look at what are the ways to defend ourselves against attacks in the case of quantum cryptography
First and foremost, using longer keys during encryption is the simplest way to protect against attacks. Although longer keys make the encryption slower and costlier. Another option is to use symmetric encryption for the transmission of messages themselves and then use asymmetric encryption for the key. The same idea is used behind transport layer security (TLS), an online standard.
The best solution would be to use a combination of post-quantum method algorithms of the likes of lattice-based encryption for an initial conversation and then securely exchange keys, main message can be encrypted using symmetric encryption
With increasing network attacks and malware, it’s becoming more important than ever to protect the data during transmission. Even if we perfect quantum technology with multiple security layers, one solution alone will be susceptible to attacks. And hence it is advised to have a hybrid solution during the communication.
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