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Cryptography
Published in R. Balakrishnan, Sriraman Sridharan, Discrete Mathematics, 2019
R. Balakrishnan, Sriraman Sridharan
At the heart of this cryptography is the concept of a “one-way function.”Roughly speaking, a one-way function is a 1–1 function f which is such that whenever k is given, it is possible to compute f(k) “rapidly” while it is “extremely difficult” to compute the inverse of f in a “reasonable” amount of time. There is no way of asserting that such and such a function is a one-way function since the computations depend on the technology of the day—the hardware and the software. So what passes for a one-way function today may fail to be a one-way function a few years later.
Introduction
Published in Vlad P. Shmerko, Svetlana N. Yanushkevich, Sergey Edward Lyshevski, Computer Arithmetics for Nanoelectronics, 2018
Vlad P. Shmerko, Svetlana N. Yanushkevich, Sergey Edward Lyshevski
An example of the application of a residue number system is public key cryptography. Two keys are used in the encryption and decryption of messages: one that must be kept secret and one that may be made public. These two keys are related mathematically by a so-called "one-way" function. A one-way function is easy to compute in one direction but very hard (computationally infeasible) to compute in the other direction. An example of a one-way function is multiplication versus factorization. It is simple to multiply two large prime numbers, but very hard to factor the result.
Systems Management
Published in Paul J. Fortier, Handbook of Local Area Network Software, 1991
If X = 10 is the plain text information, f(X) = 15020 is the cipher text. The calculation of f(X) is very straightforward. Given Equation (5) and f(X) = 15020, the value of X = 10 is not as easy to calculate. The type of one-way function often used in Public-Key cryptography is called a trapdoor function. A trapdoor function is a one-way function except that a secret means has been built into the function to allow easy deciphering. This information is very carefully hidden and without the secret key the cipher text cannot be deciphered.
Hybrid lightweight cryptography with attribute-based encryption standard for secure and scalable IoT system
Published in Connection Science, 2022
Mounika Jammula, Venkata Mani Vakamulla, Sai Krishna Kondoju
A symmetric key cypher is one in which an unvarying size block of plain text is processed via a changeable function with a key as a parameter to produce cypher text. The symmetric key cypher and stream cypher (Jammula et al., 2022) store a string of bits of plaintext with a stream of bits generated by a key when it is passed through a function, resulting in a bit string of cypher text. The hash function is a cryptographic primitive that takes a given sized block of plaintext and converts it into a unique string of bits using a one-way function. One-way functions are essential components of many tools used in contemporary cryptography. They are utilised in message authentication, digital signatures, and pseudorandom generators. Furthermore, a one-way hash function is built in such a way that identifying a text that hashes to a given value is problematic. The MAC system employs a technique that encrypts messages using session encryption and the delivered regular text communication. The information is next processed by the MAC method, which creates identification labels with a specified distance. The message's MAC is the consequence of the data processing. Message authentication codes (Kumar et al., 2022a) are cryptographic primitives that take a key and a lengthy string of bits from a message as input and output a unique shorter string of bits. It is also known as the keyed hash function.