Can two different inputs x1, x2 produce the same output y in Data Encryption Standard (DES)?
In the Data Encryption Standard (DES) block cipher cryptosystem, it is theoretically possible for two different inputs, x1 and x2, to produce the same output, y. However, the probability of this occurring is extremely low, making it practically negligible. This property is known as a collision. DES operates on 64-bit blocks of data and uses
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, DES block cipher cryptosystem, Data Encryption Standard (DES) - Key schedule and decryption
In case of an attack on a single LFSR, if attackers capture 2m bits from the middle of transmission (message) can they still calculate configuration of the LSFR (values of p) and can they decrypt in backwards direction?
In the field of classical cryptography, stream ciphers are widely used for encryption and decryption of data. One of the common techniques used in stream ciphers is the utilization of linear feedback shift registers (LFSRs). These LFSRs generate a keystream that is combined with the plaintext to produce the ciphertext. However, the security of stream
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, Stream ciphers, Stream ciphers and linear feedback shift registers
How truly random are TRNGs based on random physical processes?
Randomness is a fundamental concept in cryptography, as it plays a crucial role in ensuring the security of cryptographic systems. True Random Number Generators (TRNGs) based on random physical processes are often used to generate random numbers for cryptographic purposes. These TRNGs aim to produce unpredictable and unbiased random numbers by exploiting the inherent randomness
How many public parametres Diffie-Hellman protocol has?
The Diffie-Hellman protocol is a fundamental cryptographic algorithm used for secure key exchange between two parties over an insecure channel. It was introduced by Whitfield Diffie and Martin Hellman in 1976 and is based on the concept of the discrete logarithm problem in number theory. The protocol allows two parties, often referred to as Alice
- Published in Cybersecurity, EITC/IS/ACC Advanced Classical Cryptography, Diffie-Hellman cryptosystem, Diffie-Hellman Key Exchange and the Discrete Log Problem
Why a block cipher can be easily turned into a stream cipher while the opposite is not the case?
A block cipher can be indeed easily turned into a stream cipher while the opposite is not the case. This is due to the fundamental differences between block ciphers and stream ciphers, as well as the properties and requirements of each. To better understand this problem, let's first define what block ciphers and stream ciphers
How to account for wrapping around in a shift cipher?
In the field of classical cryptography, the shift cipher is a simple and widely used encryption technique. It operates by shifting each letter of the plaintext by a fixed number of positions in the alphabet. To account for wrapping around, where shifting beyond the end of the alphabet would result in a loop back to
Is it correct that a stream cipher using a truly random key binary sequence is the unbreakable One-Time Pad cipher?
A stream cipher is a type of encryption algorithm that operates on individual bits or bytes of plaintext and produces a corresponding stream of ciphertext. It is based on the use of a key stream, which is generated by combining a secret key with a random or pseudorandom sequence of bits. The key stream is
What does the Kerckhoffs’s principle state?
The Kerckhoffs's principle, named after the Dutch cryptographer Auguste Kerckhoffs, is a fundamental principle in the field of cryptography. It states that a cryptosystem should remain secure even if an adversary knows all the details of the system, except for the secret decryption key. In other words, the security of a cryptosystem should rely solely
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, History of cryptography, Modular arithmetic and historical ciphers
What are the three prerequisites for the one-time pad encryption method to ensure security?
The one-time pad encryption method is a cryptographic technique that provides unconditional security when implemented correctly. To ensure the security of the one-time pad, three prerequisites must be met: perfect secrecy, random key generation, and secure key distribution. Perfect secrecy is the fundamental requirement for the one-time pad encryption method. It guarantees that the ciphertext
How does understanding entropy contribute to the design and evaluation of robust cryptographic algorithms in the field of cybersecurity?
Understanding entropy is crucial in the design and evaluation of robust cryptographic algorithms in the field of cybersecurity. Entropy, in the context of classical cryptography, refers to the measure of uncertainty or randomness in a given set of data. It plays a fundamental role in ensuring the security and effectiveness of cryptographic algorithms by providing