What is the key space of an affine cipher?
The key space of an affine cipher is a fundamental concept in classical cryptography, particularly within the domain of modular arithmetic and historical ciphers. The affine cipher is a type of substitution cipher, which means it replaces each letter in the plaintext with a corresponding letter in the ciphertext according to a mathematical function. Understanding
Are letter frequency analysis attack effective against substitution cipher?
Letter frequency analysis is a technique used in cryptanalysis to break substitution ciphers, which are a type of classical cipher. A substitution cipher is a method of encoding where each letter in the plaintext is replaced with another letter. The Caesar cipher, where each letter in the plaintext is shifted a certain number of places
Are substitution ciphers an example of asymmetric ciphers?
Substitution ciphers are a type of classical cryptographic technique that have been used for centuries to encrypt messages. In the context of cryptographic methods, they fall under the category of symmetric ciphers rather than asymmetric ciphers. To understand why this is the case, it is essential to consider the definitions and characteristics of symmetric and
Can we tell how many irreducible polynomial exist for GF(2^m) ?
In the field of classical cryptography, specifically in the context of the AES block cipher cryptosystem, the concept of Galois Fields (GF) plays a important role. Galois Fields are finite fields that are extensively used in cryptography for their mathematical properties. In this regard, GF(2^m) is of particular interest, where m represents the degree of
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, AES block cipher cryptosystem, Introduction to Galois Fields for the AES
Why in FF GF(8) irreducible polynomial itself does not belong to the same field?
In the field of classical cryptography, particularly in the context of the AES block cipher cryptosystem, the concept of Galois Fields (GF) plays a important role. Galois Fields are finite fields that are used for various operations in AES, such as multiplication and division. One important aspect of Galois Fields is the existence of irreducible
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, AES block cipher cryptosystem, Introduction to Galois Fields for the AES
At the stage of S-boxes in DES since we are reducing fragment of a message by 50% is there a guarantee we don’t loose data and message stays recoverable / decryptable?
At the stage of S-boxes in the Data Encryption Standard (DES) block cipher cryptosystem, the reduction of the message fragment by 50% does not result in any loss of data or render the message unrecoverable or undecryptable. This is due to the specific design and properties of the S-boxes used in DES. To understand why
- Published in Cybersecurity, EITC/IS/CCF Classical Cryptography Fundamentals, DES block cipher cryptosystem, Data Encryption Standard (DES) - Encryption
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
What is the difference between a MAC and HMAC, and how does HMAC enhance the security of MACs?
A Message Authentication Code (MAC) is a cryptographic technique used to ensure the integrity and authenticity of a message. It involves the use of a secret key to generate a fixed-size tag that is appended to the message. The receiver can then verify the integrity of the message by recomputing the tag using the same
What is the purpose of a message authentication code (MAC) in classical cryptography?
A message authentication code (MAC) is a cryptographic technique used in classical cryptography to ensure the integrity and authenticity of a message. The purpose of a MAC is to provide a means of verifying that a message has not been tampered with during transmission and that it originates from a trusted source. In classical cryptography,
What are the weaknesses of the secret prefix and secret suffix methods for constructing MACs?
The secret prefix and secret suffix methods are two commonly used techniques for constructing Message Authentication Codes (MACs) in classical cryptography. While these methods have their advantages, they also possess certain weaknesses that need to be considered when implementing MACs. In this answer, we will explore the weaknesses of both the secret prefix and secret
- Published in Cybersecurity, EITC/IS/ACC Advanced Classical Cryptography, Message Authentication Codes, MAC (Message Authentication Codes) and HMAC, Examination review
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