An attacker sniffs encrypted traffic from the network and is subsequently able to decrypt it. The attacker can now use which cryptanalytic technique to attempt to discover the encryption key?
An attacker sniffs encrypted traffic from the network and is subsequently able to decrypt it. The attacker can now use which cryptanalytic technique to attempt to discover the encryption key?
An attacker who is able to decrypt encrypted traffic and wishes to discover the encryption key might use a chosen ciphertext attack. In this type of attack, the attacker can choose ciphertexts and obtain their corresponding plaintexts, allowing them to potentially derive the encryption key through analysis. This matches the scenario described where the attacker can already decrypt traffic and may choose specific ciphertexts to work with.
What is the difference between chosen plaintext and chosen ciphertext attack? In both of cases, adversary has access to paintext-ciphertext pairs. Where lies the difference? The difference is how the plaintext-ciphertext pairs that the attacker has access to are generated. In a chosen plaintext attack, the attacker can even choose some plaintext and is handed the corresponding ciphertext. In other words, the attacker may encrypt arbitrary messages. In a chosen ciphertext attack, the attacker can additionally choose some ciphertext and is handed the corresponding plaintext. In other words, the attacker may encrypt and decrypt arbitrary messages.
In chosen cyphertext attack Attacker has many samples of encrypted text acquired from sniffing and is able to decrypt arbitarary sample of text. This is chosen cypher text attack beacuse attacker can choose arbitary encrypted text and decrypt it. Observing output and comparing this to input samples he can deduct the encryption key. Chosen-plaintext attack is an opposite attack to chosen-cypher text attack. in Chosen-cypher text attack attacker chooses samples of plaintext, encrypt it and compares output with inputs to deduct encryption key. Question in exam is a bit stupid. Normally doing sniffing is rather unlikely that attacker can decrypt payload and still be looking for encryption key that is often specyfic to session.