Survey on Cryptanalysis:

Cryptanalysis refers to the study of ciphers, ciphertext, or cryptosystems (that is, to secret code systems) with a view to finding weaknesses in them that will permit retrieval of the plaintext from the ciphertext, without necessarily knowing the key or the algorithm. This is known as breaking the cipher, ciphertext, or cryptosystem.

Breaking is sometimes used interchangeably with weakening. This refers to finding a property (fault) in the design or implementation of the cipher that reduces the number of keys required in a brute force attack (that is, simply trying every possible key until the correct one is found). For example, assume that a symmetric cipher implementation uses a key length of 2^128 bits (2 to the power of 128): this means that a brute force attack would need to try up to all 2^128 possible combinations (rounds) to be certain of finding the correct key (or, on average, 2^127 possible combinations) to convert the ciphertext into plaintext, which is not possible given present and near future computing abilities. However, a cryptanalysis of the cipher reveals a technique that would allow the plaintext to be found in 2^40 rounds. While not completely broken, the cipher is now much weaker and the plaintext can be found with moderate computing resources.

There are numerous techniques for performing cryptanalysis, depending on what access the cryptanalyst has to the plaintext, ciphertext, or other aspects of the cryptosystem. Below are some of the most common types of attacks:

1. Known-plaintext analysis
With this procedure, the cryptanalyst has knowledge of a portion of the plaintext from the ciphertext. Using this information, the cryptanalyst attempts to deduce the key used to produce the ciphertext

2. Chosen PlainText Analysis
The cryptanalyst is able to have any plaintext encrypted with a key and obtain