Cryptanalysis Attacks

In this class, We discuss Cryptanalysis Attacks.

The reader should have prior knowledge of additive cipher. Click here.

Crypt analysis is a method to break the secret codes.

There are four ways to do crypt analysis.

1) Cipher text-only attack

2) Known plain text attack

3) Chosen plain text attack

4) Chosen ciphertext attack

Cryptography algorithms are open to all.

Once we find the cipher text, finding the key should be difficult in cryptography.

1) Cipher text-only attack: we discuss two methods

Brute force attack

Statistical attack.

In the brute force attack we try different possible keys and find the plain text.

In a statistical attack, we find the frequency of characters based on language and find the key.

In English the character “e” is obtained 12 percent times.

By looking at the cypher text, the most frequently occurred character is considered as “e”.

Known plain text attack:

If we have cipher text and plain text pairs, then identifying the key from these pairs is called a known plain text attack.

Chosen plain text attack:

If we have access to the source mobile.

We can collect chosen plain text and cipher text pairs.

Using this chosen plain text and cipher text pairs is called a chosen plain text attack.

Chosen cipher text attack:

If we have access to the destination mobile.

We can find chosen cipher text and plain text pairs.

Finding the key from these pairs is called chosen ciphertext attack.