PUBLIC KEY ENCRYPTION:
1. Public key encryption is also called Asymmetric encryption. It uses the concept of a key value pair, a different key is used for the encryption and decryption process. One of the keys is typically known as the private key and the other is known as the public key.
2. The private key is kept secret by the owner and the public key is either shared amongst authorized recipients or made available to the public at large.
3. The data encrypted with the recipient's public key can only be decrypted with the corresponding private key.

CRACKING:
1. Cracking is where someone edits a program source so that the code can be exploited or modified. A cracker (also called a black hat or dark side hacker) is a malicious or criminal hacker
2. "Cracking" means trying to get into computer systems in order to steal, corrupt, or illegitimately view data.
3. A cracker is someone who breaks into someone else's computer system, often on a network, bypassing passwords or licenses in computer programs
4. Software cracking is the most often used  of cracking which is nothing but removing tl, encoded copy protection.
5. There is another type of cracking called password cracking. This is mainly used to crack the passwords. Password cracking can be performed either by using an automated program or can be manually realized.
6. One more interesting fact apout cracking is social engineering. It is a method of getting passwords and information using human weakness
7. The other method that uses social engineering crackers is password guessing.
8. They find your personal information from some personal datal facts and try to guess a password
9. Usually a cracker maintains knowledge of the vulnerabilities he or she finds and exploits them for personal advantage, not revealing them to either to the general public or to the manufacturer.

Types of Encryption :
There are two types of encryption schemes as listed below:
i. Synunetric Key encryption,
ii. Public Key encryption.
Symmetric Key Encryption :
Symmetric encryption is a technique to use the same key for both encryption and decryption. The main disadvantage of the symmetric key encryption is that all authorized persons involved, have to exchange the key used to encrypt the data before they can decrypt it. If anybody intercepts the key information, they may read all message. Depicts the working of symmetric key encryption.
Public Key Encryption:
Public key encryption is also called Asymmetric encryption. It uses the concept of a key value pair, a different key is used for the encryption and decryption process. One of the keys is typically known as the private key and the other is known as the public key. The private key is kept secret by the owner and the public key is either shared amongst authorized recipients or made available to the public at large. The data encrypted with the recipient's public key can only be decrypted with the corresponding private key. public key encryption.

(i) Social engineering:
A misuse of an individual's weakness, achieved by making them to click malicious links, or by physically accessing the computer through tricks. Phishing and pharming are examples of social engineering.
(ii) Phishing:
Phishing is a type of computer crime used to attack, steal user data, including login name, password and credit card numbers. It occurs when an attacker targets a victim into opening an e-mail or an instant text message. The attacker uses phishing to distribute malicious links or attachments that can perform a variety of functions. including the extraction of sensitive login credentials from victims.
(iii) Pharming:
Pharming is a scamming practice in which malicious code is installed on a personal computer or server, misdirecting users to fraudulent web sites without their knowledge or permission.Pharming has been called "phishing without a trap" It is another way hackers attempt to manipulate users on the Internet. It is a cyber attack intended to redirect a website's traffic to a fake site.