In cryptography a key is a piece of information (parameter) that determines the functional output of a cryptographic algorithm.

Cyber attacks are launched primarily or causing significant damage to a computer system or for stealing important information from an individual or from an organization.

Password cracking is the process of using an application program to identify an unknown or forgotten password to a computer or network resource. It can also be used to help a threat actor obtain unauthorized access to resources.  A password cracker recovers passwords using various techniques.

Unauthorized access is when someone gains access to a website, program, server, service, or other system by breaking into a legitimate user account.

It includes stealing of codes/ programs and other information illegally and creating duplicate copies by unauthorized means and utilizing this data either for one's own benefit or for commercial profit.

Firewall Server:
A firewall is a computer network security-based system that monitors and controls the incoming and outgoing network traffic based on predefined security rules. A firewall commonly establishes a block between a trusted internal computer network and entrusted computer outside the network.
They are generally categorized as network-based or host-based.
1. Network-based firewalls are positioned on the gateway computers of LANs [local area Network], WANs [Wide Area Network], and intranets,
2. Host-based firewalls are positioned on the network node itself. The host-based firewall may be a service as a part of the operating system or an agent application such as endpoint security or protection.

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.

Digital signature :
(i) Digital signatures are based on asymmetric cryptography and can provide -assurances of evidence to origin, identity and status of an electronic document, transaction or message, as well as acknowledging informed by the signer.
(ii) To create a digital signature, signing software (email) creates a one-way hash of the electronic data to be signed.
(iii) The user's private key to encrypt the hash, returning a value that is unique to the hashed data. The encrypted hash, along with other information such as the hashing algorithm, forms the digital signature. Any change in the data, even to a single bit, results in a different hasp value.

(iv) This attribute enables others to validate the integrity of the data by using the signer's public key to decrypt the hash. If the decrypted hash matches a second computed hash of the same data, it proves that the data hasn't changed since it was signed.
(v) If the two hashes don't match, the data has either been tampered with in some way (indicating a failure of integrity) or the signature was created with a private key that doesn't correspond to the public key presented by the signer (indicating a failure of authentication).

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.

To protect the information the following points to be noted:
1. Complex password settings can make your surfing secure.
2. When the internet is not in use, disconnect it.
3. Do NOT open spam mail or emails that have an unfamiliar sender.
4. When using anti-virus software, keep it up to- date

1. A proxy server acts as an intermediary between the end users and a web server. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resources available from a different server.
2. The proxy server examines the request, checks authenticity and grants the request based on that. Proxy servers typically keep the frequently visited site addresses in its cache which leads to improved response time.

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 cyberattac intended to redirect a website's traffic to a fake site.

Phishing:
1. 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-rnailer an instant text message.
2. 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.

UNAUTHORIZED ACCESS:
1. Unauthorized access is when someone gains access to a website, program, server, service, or other system by breaking into a legitimate user account.
2. For example, if someone tries guessing a password or user name for an account that was not theirs until they gained access, it is considered an unauthorized access.