Cryptanalytic Attack

Cryptanalytic Attack is performed based on the nature of the cryptographic #algorithm with the complement from the general characteristic of the plaintext. It is essentially finding a relationship between the plaintext and the ciphertext. Some #Cryptanalysts would use the sample plaintext-ciphertext pairs in aid on cracking the algorithm down. The purpose of the Cryptanalytic Attack is to find the relationship between the information that the cryptanalyst has obtained.

The goal of a Cryptanalytic Attack, rank from highest security threat to lowest, is to:

have a total break of the encryption scheme, that is getting hold of the private or decryption key
to decrypt some ciphertexts
to distinguish pairs of ciphertexts based on the message

With the assumption that the algorithm is known#, ranked from weak to strong, the intruder could carry out efficient attack if they have obtained the information of:

only ciphertext (COA)
known/suspect plaintext (KPA)
chosen plaintext, where the intruder obtained the encryption oracle (black box), which the plaintext could be used to produce ciphertext (e.g., Differential Cryptanalysis Attack#, Integral Cryptanalysis Attack#) (CPA)
chosen ciphertext, where the intruder obtained the decryption oracle, which the ciphertext could be used to produce plaintext (CCA)
chosen text, where the intruder obtained the cryptographic oracle, that is the entire system, which can produce either plaintext or ciphertext (CTA)

Other than the above attacks, there are some more attacks utilising different characteristic of the encryption scheme:

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Vigenère Cipher

However, Vigenère Cipher not entirely secure as the key could be repeated thus make it vulnerable to Frequency Analysis if there is too many repetitions. Another way to attack it is by guessing the number of alphabets being used, and then attack by brute force. If the key is too short, then it is easy to break with Kasiski Method#.
TNS3131 Chapter 2: Conventional Encryption and Message Confidentiality

Cryptanalytic Attack
TAC3121 Chapter 4: Asymmetric (Public-Key) Encryption

Cryptanalytic Attack
TAC3121 Chapter 1: Introduction

Cryptanalytic Attack
Side-Channel Attack

Side-Channel Attack is a kind of #Cryptanalytic Attack focuses on the time taken to respond to specific queries, total power consumption, or electromagnetic radiation emitted by the encryption scheme.
Rivest-Shamir-Adleman (RSA)

The security of RSA is guarantee by its Trapdoor One-Way Function# nature as primes \(p\) and \(q\) are only known to the key owner. It is impossible to do a Brute Force Attack on RSA due to the large key size. Other Cryptanalytic Attack such as mathematical attack based on difficulty of computing \(\phi(n)\), by factoring modulus \(n\) (can be overcome by having a larger \(n\)), timing attacks# on decryption algorithm, and chosen ciphertext attacks (CCA) can be done on RSA.
Permutation/Transposition Cryptography

A Cryptanalytic Attack done on Permutation/Transposition Cryptographic algorithm is by first guessing period, try all possible permutation on the period (Brute Force Attack), search for common patterns and then use lists of common diagrams and trigrams (Frequency Analysis#).
Meet-In-The-Middle (MITM)

MITM is a #known plaintext attack on an #encryption scheme by obtaining the ciphertext in between two encryption algorithms, and comparing the encrypted output from the plaintext and decrypted output from the final ciphertext. This process could be further understood with the following equation:
Man-In-The-Middle Attack (MITM)

MITM is a #Cryptanalytic Attack where the Cryptanalyst found a way to be in between two parties in a communication channel. It is exceptionally dangerous to encryption scheme that involves key exchange such as Symmetric Cryptography# and Asymmetric Cryptography#. It is form of #Interception.
Kasiski Method

Kasiski Method is a #Cryptanalytic Attack, developed by Baddage and Kasiski, attempts to break #Polyalphabetic Cipher by deducing the length of the keyword. The repetition in the ciphertext, especially in Vigenère Cipher gives clues to the key length by examining the period apart between multiple identical ciphertext patterns and find out the common factor# of the distances (excluding 1 as a possible key length). After that, we could easily do a Frequency Analysis on the ciphertext.
Integral Cryptanalysis Attack

Integral Cryptanalysis Attack is a #chosen plaintext attack utilising sets of plaintexts in which part of the plaintext is kept unchanged but with slight modification on the rest.
Indistinguishability Against Chosen Ciphertext Attack (IND-CCA)

IND-CCA is the highest security notion for an encryption scheme#. It is resistant to the most lenient Cryptanalytic Attack#, that is to distinguish two ciphertexts using chosen ciphertext attack.
Frequency Analysis

Frequency Analysis is a #Cryptanalytic Attack utilises the nature of natural language (human language) where there is redundancy in letter usage. Not every letter has the same frequency as others.
Digital Signature

Note: Hashing is used to avoid certain attacks.
Differential Cryptanalysis Attack

Differential Cryptanalysis Attack is a #chosen plaintext attack on block ciphers which the Cryptanalyst analyses the relationship of pairs of plaintexts to the targeted algorithm.
Cryptanalysis

Cryptanalytic Attack#
Chosen Ciphertext Attack (CCA) on RSA

We can take advantage of the multiplicative nature of #Rivest-Shamir-Adleman (RSA) and utilise it in our attempts to carry out #CCA. The multiplicative properties of RSA is stated below:
Chosen Ciphertext Attack (CCA) on El Gamal

We could perform a #CCA on El Gamal Encryption# with the following steps assuming that we have the ciphertext \(C = (c_1, c_2)\):
Brute Force Attack

If a #Cryptanalysis could crack an encryption scheme with an attempts less than of the Brute Force Attack, then it is considered to be a Cryptanalytic Attack on the scheme.
Asymmetric Cryptography

In addition, it is a must for an Asymmetric Cryptographic scheme to be resistant against Chosen Plaintext Attack (CPA)# since owning the public-key render a full control over the encryption algorithm. Otherwise, the scheme would be useless.
Analytic Attacks

Analytic Attacks is a #Cryptanalytic Attack utilising the encryption information gathered before carrying out attack to recover some or all subkey bits and if necessary involving Brute Force Attack#. They are generally categorised as statistical attacks.

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