A digital certificate is issued by a certificate authority to verify an individual's or entity's identity, linking their public key with their identification information. It differs from a digital signature, which validates the authenticity and integrity of a message, while both are essential for security. Additionally, various internet security protocols exist, including SSL, TLS, and different types of firewalls, which protect data and networks from unauthorized access and ensure secure communications.

1. Digital Certificate
Digital certificate is issued by a trusted third party which proves sender’s identity to the
receiver and receiver’s identity to the sender.
A digital certificate is a certificate issued by a Certificate Authority (CA) to verify the
identity of the certificate holder. The CA issues an encrypted digital certificate containing
the applicant’s public key and a variety of other identification information. Digital
certificate is used to attach public key with a particular individual or an entity.
Digital certificate contains:- The authenticity
1. Name of certificate holder.
2. Serial number which is used to uniquely identify a certificate, the individual or the
entity identified by the certificate
3. Expiration dates.
4. Copy of certificate holder’s public key.(used for decrypting messages and digital
signatures)
5. Digital Signature of the certificate issuing authority.
Digital certificate is also sent with the digital signature and the message.
Digital certificate vs digital signature :
Digital signature is used to verify authenticity, integrity, non-repudiation ,i.e. it is assuring that
the message is sent by the known user and not modified, while digital certificate is used to
verify the identity of the user, maybe sender or receiver. Thus, digital signature and certificate
are different kind of things but both are used for security. Most websites use digital certificate
to enhance trust of their users

2. Feature Digital Signature Digital Certificate
Basics /
Definition
Digital signature is like a fingerprint or an
attachment to a digital document that ensures
its authenticity and integrity.
Digital certificate is a file that ensures holder’s
identity and provides security.
Process / Steps
Hashed value of original message is encrypted
with sender’s secret key to generate the digital
signature.
It is generated by CA (Certifying Authority) that
involves four steps: Key Generation, Registration,
Verification, Creation.
Security
Services
Authenticity of Sender, integrity of the
document and non-repudiation.
It provides security and authenticity of
certificate holder.
Standard It follows Digital Signature Standard (DSS). It follows X.509 Standard Format

3. Public key– Key which is known to everyone. Ex-public key of A is 7, this information
is known to everyone.
Private key– Key which is only known to the person who’s private key it is.
Digital Signature
A digital signature is a mathematical technique used to validate the authenticity and
integrity of a message, software, or digital document.
Digital signature is electronic signatures, which assure that the message was sent by
a particular sender. While performing digital transactions authenticity and integrity
should be assured, otherwise, the data can be altered or someone can also act as if
he was the sender and expect a reply

4. Types of Internet Security Protocols
In today’s world, we transfer the data in bulk, and the security of this data is very important,
so Internet security provides that feature i.e., protection of data. There are different types of
protocol exist like routing, mail transfer, and remote communication protocol. But the Internet
security protocol helps in the security and integrity of data over the internet. There are many
protocols that exist that help in the security of data over the internet such as Secure Socket
Layer (SSL), Transport Layer Security (TLS).
SSL Protocol :
•SSL Protocol stands for Secure Sockets Layer protocol, which is an encryption-based
Internet security protocol that protects confidentiality and integrity of data.
•SSL is used to ensure the privacy and authenticity of data over the internet.
•SSL is located between the application and transport layers.
•At first, SSL contained security flaws and was quickly replaced by the first version of
TLS that’s why SSL is the predecessor of the modern TLS encryption.
•TLS/SSL website has “HTTPS” in its URL rather than “HTTP”.
•SSL is divided into three sub-protocols: the Handshake Protocol, the Record
Protocol, and the Alert Protocol.

5. TLS Protocol :
•Same as SSL, TLS which stands for Transport Layer Security is widely used for the
privacy and security of data over the internet.
•TLS uses a pseudo-random algorithm to generate the master secret which is a key
used for the encryption between the protocol client and protocol server.
•TLS is basically used for encrypting communication between online servers like a
web browser loading a web page in the online server.
•TLS also has three sub-protocols the same as SSL protocol – Handshake Protocol,
Record Protocol, and Alert Protocol.
SHTTP :
•SHTTP stands for Secure HyperText Transfer Protocol, which is a collection of
security measures like Establishing strong passwords, setting up a firewall, thinking
of antivirus protection, and so on designed to secure internet communication.
•SHTTP includes data entry forms that are used to input data, which has previously
been collected into a database. As well as internet-based transactions.
•SHTTP’s services are quite comparable to those of the SSL protocol.
•Secure HyperText Transfer Protocol works at the application layer (that defines the
shared communications protocols and interface methods used by hosts in a network)
and is thus closely linked with HTTP.
•SHTTP can authenticate and encrypt HTTP traffic between the client and the server.
•SHTTP operates on a message-by-message basis. It can encrypt and sign individual
messages.

6. Types of Firewalls in Network Security
Nowadays, protecting our sensitive data from unauthorized and unwanted sources has
become a significant challenge. There are numerous tools available that can provide various
levels of security and aid in the protection of private information stored in any system. A
‘firewall’ is a network security mechanism that protects our systems and data against
unauthorized access.
A firewall is a cybersecurity device or software application that filters network traffic. A
firewall acts as a traffic cop at your computer’s port. A fundamental purpose of a firewall
is to create a barrier that separates an internal network from incoming external traffic to
block malicious traffic requests and data packets, such as malware and hacking while
allowing legitimate traffic to pass through. A firewall enables only the traffic that has
been configured to accept, like IP addresses. It differentiates between legitimate and
malicious traffic and allows or blocks specific data packets based on predefined security
rules.

7. A Firewall is a necessary component of a company’s overall cybersecurity strategy. Most
computers have an in-built firewall, but it isn’t always the best option for security. What
can a firewall do to keep us safe?
It guards computers against unauthorized access.
It blocks unwanted content.
It provides a secure network when multiple people interact at the same time.
It prevents ransomware from spreading.
It protects private information, such as online banking credentials.
Types of Network Firewall :
Packet Filters –
It is a technique used to control network access by monitoring outgoing and incoming
packets and allowing them to pass or halt based on the source and destination Internet
Protocol (IP) addresses, protocols, and ports. This firewall is also known as a static
firewall.
Stateful Inspection Firewalls –
It is also a type of packet filtering which is used to control how data packets move
through a firewall. It is also called dynamic packet filtering. These firewalls can inspect
that if the packet belongs to a particular session or not. It only permits communication if
and only if, the session is perfectly established between two endpoints else it will block
the communication.

8. Application Layer Firewalls –
These firewalls can examine application layer (of OSI model) information like an HTTP
request. If finds some suspicious application that can be responsible for harming our
network or that is not safe for our network then it gets blocked right away.
Next-generation Firewalls –
These firewalls are called intelligent firewalls. These firewalls can perform all the tasks that
are performed by the other types of firewalls that we learned previously but on top of that, it
includes additional features like application awareness and control, integrated intrusion
prevention, and cloud-delivered threat intelligence.
Circuit-level gateways –
A circuit-level gateway is a firewall that provides User Datagram Protocol (UDP) and
Transmission Control Protocol (TCP) connection security and works between an Open
Systems Interconnection (OSI) network model’s transport and application layers such
as the session layer.

9. Software Firewall –
The software firewall is a type of computer software that runs on our computers. It protects
our system from any external attacks such as unauthorized access, malicious attacks, etc. by
notifying us about the danger that can occur if we open a particular mail or if we try to open
a website that is not secure.
Hardware Firewall –
A hardware firewall is a physical appliance that is deployed to enforce a network boundary.
All network links crossing this boundary pass-through this firewall, which enables it to
perform an inspection of both inbound and outbound network traffic and enforce access
controls and other security policies.
Cloud Firewall –
These are software-based, cloud-deployed network devices. This cloud-based firewall
protects a private network from any unwanted access. Unlike traditional firewalls, a cloud
firewall filters data at the cloud level.