Do the encryption and decryption functions need to be kept secret for the cryptographic protocol to remain secure?
The security model underlying modern cryptography is based on several well-established principles, the foremost of which is Kerckhoffs’s Principle. This tenet asserts that the security of a cryptographic protocol should rely solely on the secrecy of the key, not on the secrecy of the algorithms used for encryption or decryption. Hence, to address the question:
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, Introduction, Introduction to cryptography
Can cryptanalysis be used to communicate securely over an insecure communication channel?
Cryptanalysis, by its definition, is the study and practice of analyzing information systems in order to understand hidden aspects of the systems, typically with the intent of breaking cryptographic security systems and gaining access to the contents of encrypted messages, without being provided with the key normally required to do so. The term is fundamentally
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, Introduction, Introduction to cryptography
Do Internet, GSM, and wireless networks belong to the insecure communication channels?
Internet, GSM, and wireless networks are all considered insecure communication channels from the perspective of classical and modern cryptography. To understand why this is the case, one must examine the inherent properties of these channels, the types of threats they face, and the security assumptions made in cryptographic protocol design. 1. Definition of Secure vs.
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, Introduction, Introduction to cryptography
Is an exhaustive key search effective against substitution ciphers?
An exhaustive key search, also known as brute-force attack, involves systematically trying every possible key in the keyspace of a cipher until the correct key is found. The effectiveness of such an approach depends greatly on the size of the keyspace, which is determined by the number of possible keys, and the structure of the
Does the AES MixColumn sublayer include a nonlinear transformation that can be represented by a 4×4 matrix multiplication?
The Advanced Encryption Standard (AES) is a widely adopted symmetric key block cipher, and its security is derived from a carefully orchestrated series of linear and nonlinear transformations on the data block. One of the key components in AES is the MixColumns sublayer, which plays a critical role in providing diffusion by mixing the columns
Is the encryption function in the RSA cipher an exponential function modulo n and the decryption function an exponential function with a different exponent?
The RSA cryptosystem is a foundational public-key cryptographic scheme based on number-theoretic principles, specifically relying on the mathematical hardness of factoring large composite numbers. When examining the encryption and decryption functions in RSA, it is both accurate and instructive to characterize these operations as modular exponentiations, each employing a distinct exponent. Key Generation in RSA
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, Introduction to public-key cryptography, The RSA cryptosystem and efficient exponentiation
What does Fermat’s Little Theorem state?
Fermat's Little Theorem is a foundational result in number theory and plays a significant role in the theoretical underpinnings of public-key cryptography, particularly in the context of algorithms such as RSA. Let us analyze the theorem, its statement, and its didactic value, specifically within the context of cryptography and number theory. Correct Statement of Fermat’s
Are quantum random numbers generators the only real nondeterministic random numbers generators?
Quantum random number generators (QRNGs) have gained significant attention in both academic and applied cryptography circles due to their ability to produce random numbers based on inherently unpredictable quantum phenomena. To fully address whether QRNGs are the only "real nondeterministic true random number generators," it is necessary to examine the concepts of randomness, determinism, and
Do practical stream ciphers distribute the truly random key?
The question of whether practical stream ciphers distribute a truly random key engages foundational cryptographic principles, especially concerning the distinction between theoretical constructs like the one-time pad and real-world algorithms designed for feasible deployment. Addressing this question requires clarifying several terms: what is meant by a “truly random key,” how stream ciphers generate their keystreams,
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, Stream ciphers, Stream ciphers, random numbers and the one-time pad
What does the value K stand for in a shift cipher?
In classical cryptography, particularly in the context of the shift cipher—which is often referred to as the Caesar cipher—the value denoted by represents the key used for both encryption and decryption processes. The shift cipher is a type of substitution cipher where each letter in the plaintext is shifted by a fixed number of positions
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, History of cryptography, Modular arithmetic and historical ciphers