Introduction to Classical Cryptography

Summary

In today's world, with societies of information that transmits a growing number of personal data via public channels, the protection of information is a global challenge. It is the technique used to authenticate users among two parties in the public environment, where there are unauthorized users and suspicious activities. Two types of process involved in classical cryptography are encryption and decryption, which are performed at the sender and receiver sides, respectively. Encryption is the method by which legible data or plain text is combined with key (additional information) and converted into an illegible data or cipher text. Decryption is the method by which cipher text is again transformed to plain text. Classical cryptography depends on mathematics and on the complexity of computing factorization in large numbers. The two major categories of classical cryptography are symmetric key cryptography and asymmetric key cryptography. In symmetric classical, both encryption and decryption are done using same key called private key [1]. In asymmetric classical, the sender uses public key to encrypt the message and the receiver uses private key to decrypt the message. The most widely used conventional cryptographic scheme is Data Encryption Standard (DES), Advanced Data Encryption Standard (AES), and Rivest‐Shamir‐Adleman (RSA). These algorithms have a primary advantage of flexibility and their protection, based on computational and validated security claims. The disadvantage relies on security of protocols against adversary.

Message authentication code (MAC) plays an important role in classical cryptography. MAC value ensures the authenticity and data privacy of message, and it will detect any changes in the transformed messages. Secure Hash Algorithm, also known as SHA, is a family of cryptographic approaches that is used to keep the information secured [2]. SHA and MAC functions generally include bitwise operations, compression functions, and modular operations. All cryptographic approaches should fulfill the security features such as confidentiality, integrity, privacy, reliability, authentication, and non‐repudiation. Cryptography tools are far more effective in the instances of signatures confirmation, user authentication, and to conduct other cryptography practices. The most extensively used classical cryptographic tools are security token, Java Cryptographic Libraries (JCA), Docker, and authentication keys. The major applications of cryptography implies banking, digital currencies, military communications, secure network communications, disk encryption, health care, education, software, and marketing.