Cryptology & Security Mechanisms

Cryptology is study of codes, both creating them ( how to protect data) and solving them (how to access protected data).

Cryptography

It is the study and application of codes and methodologies that secure information from access by unintended parties.

It enables unauthorized or malicious users from accessing data while still enabling the intended users to do so.

It includes all the methods that are used to keep the communication between two parties secret in a way that no one else can read, interpret, modify, or otherwise steal the message.

Cryptanalysis

It is technique of decoding messages from a non-readable format to readable format without knowing the key.

Or

It is a science of recovering the plaintext of messages without having access to the key.

Cryptanalysis is used to break cryptographic security system and gain access to the contents of encrypted messages, even if cryptographic key is unknown.

Types of Cryptanalytic attacks:

i. Ciphertext only attack

Attacker knows only ciphertext

ii. Known plaintext only attack

Attacker knows some combination of Pi, Ci (plain text, Ciphertext) and based on these, he try to decrypt the messages.

iii. Chosen plaintext attack

Attacker can choose random plaintexts to be encrypted and obtain the corresponding ciphertexts.

iv. Chosen Cipher attack

Cryptanalyst can choose different ciphertexts to be decrypted and has access to the decrypted plaintext.

v. Man-in-the-Middle attack

Cryptographic communications and key exchange protocols are susceptible to an attack in which the attacker is able to place himself on the communication line between tow parties.

vi. Brute Force Attack

It involves trying all possible keys until hitting on the one that results in plaintext.

etc…..

Security Mechanisms

These are set of processes that deal with recovery from security attacks. i.e. they are used to provide security.

Various mechanisms are designed to recover from these specific attacks at various protocol layers.

I. Encipherment

Hiding and covering of data which helps to become confidential. It uses some mathematical algorithms to transform data into a not readable form.

II. Digital Signature

It is from of electronic signature which is added by sender which is checked by receiver electronically. This mechanism is used to preserve data which is not more confidential but sender’s identity is to be notified.

III. Data Integrity

This security mechanism is used by appending value to data to which is created by data itself. It is similar to sending packet of information known to both sending and receiving parties and checked before and after data is received. If both the check values are same, the integrity of data is preserved.

IV. Authentication Exchange

In this, two entities exchange some messages to prove their identities to each other.

V. Traffic Padding/ Bit Stuffing

In this technique, we add some extra/dummy bits with the data while encrypting it. It helps data to be checked at the receiving end and is achieved by Even parity or Odd parity.

VI. Routing Control

Selecting or continuously changing the different available routes between the sender and receiver to prevent the attacker from eavesdropping on a particular route.

VII. Access Control

This mechanism is used to stop unattended access to data which you are sending. It can be achieved by various techniques such as applying passwords, using firewall, or just by adding PIN to data.

VIII. Notarization

This security mechanism involves use of trusted third party in communication. It acts as mediator between sender and receiver so that if any chance of conflict is reduced. This mediator keeps record of requests made by sender to receiver for later denied.