Academicians

 In the case of updating the database, the responsibility of the system  is to check whether the existing functional dependencies are getting  violated during the process of updating. In case of a violation of  functional dependencies in the new database state, the rollback of  the system must take place. A canonical cover or irreducible a set of functional dependencies  FD is a simplified set of FD that has a similar closure as the original  set FD. Extraneous attributes An attribute of an FD is said to be extraneous if we can remove it  without changing the closure of the set of FD. Example: Given a relational Schema R( A, B, C, D) and set of  Function Dependency FD = { B → A, AD → BC, C → ABD }.  Find the canonical cover? Solution: Given FD = { B → A, AD → BC, C → ABD }, now  decompose the FD using decomposition rule( Armstrong Axiom ). 1. B → A 2. AD → B ( using decomposition inference rule on AD →  BC) 3. AD → C ( using de...

 The functional dependency is a relationship that exists between two  attributes. It typically exists between the primary key and non-key  attribute within a table. 1. X → Y  The left side of FD is known as a determinant, the right side of the  production is known as a dependent. For example: Assume we have an employee table with attributes: Emp_Id,  Emp_Name, Emp_Address. Here Emp_Id attribute can uniquely identify the Emp_Name attribute of employee table because if we know the Emp_Id, we can  tell that employee name associated with it.

 Virus and Worms Computer virus is a program that can “infect” legitimate programs by modifying them to  include a possibly “evolved” copy of itself.  Viruses spread themselves, without the knowledge or permission of the users, to  potentially large numbers of programs on many machines.  A computer virus passes from computer to computer in a similar manner as a biological  virus passes from person to person.  Viruses may also contain malicious instructions that may cause damage or annoyance;  the combination of possibly Malicious Code with the ability to spread is what makes  viruses a considerable concern. Computer virus has the ability to copy itself and infect the system.  The term virus is also commonly but erroneously used to refer to other types of malware,  Adware and Spyware programs that do not have reproductive ability.  A true virus can only spread from one system to another (in some form of executable  code) when its host is taken...

Keyloggers and Spywares  Keystroke logging, often called keylogging, is the practice of noting (or logging) the keys  struck on a keyboard, typically in a covert manner so that the person using the keyboard  is unaware that such actions are being monitored.  Keystroke logger or keylogger is quicker and easier way of capturing the passwords and  monitoring the victims’ IT savvy behavior. It can be classified as software keylogger and  hardware keylogger. Software Keyloggers  Software keyloggers are software programs installed on the computer systems which  usually are located between the OS and the keyboard hardware, and every keystroke is  recorded. Software keyloggers are installed on a computer system by Trojans or viruses without the  knowledge of the user.   Cybercriminals always install such tools on the insecure computer systems available in  public places (i.e., cybercafés, etc) and can obtain the required information about the...

 Password Cracking  Password is like a key to get an entry into computerized systems like a lock.  Password cracking is a process of recovering passwords from data that have been stored in or transmitted by a computer system.  Usually, an attacker follows a common approach – repeatedly making guesses for  the password. The purpose of password cracking is as follows: 1. To recover a forgotten password. 2. As a preventive measure by system administrators to check for easily crackable  passwords. 3. To gain unauthorized access to a system. Manual password cracking is to attempt to logon with different passwords. The attacker  follows the following steps: Find a valid user account such as an Administrator or Guest; 2. create a list of possible passwords; 3. rank the passwords from high to low probability; 4. key-in each password; 5. try again until a successful password is found. Passwords can be guessed sometimes with knowledge of the user’s personal  informatio...

Phishers work in the following ways: 1. Planning: Criminals, usually called as phishers, decide the target. 2. Setup: Once phishers know which business/business house to spoof and who their  victims. 3. Attack: the phisher sends a phony message that appears to be from a reputable source. 4. Collection: Phishers record the information of victims entering into webpages or pop￾up windows. 5. Identity theft and fraud: Phishers use the information that they have gathered to make  illegal purchases or commit fraud. Nowadays, more and more organizations/institutes provide greater online access for their customers and hence criminals are successfully using Phishing techniques to steal personal information and conduct ID theft at a global level