Secure Socket Layer (SSL)
What is a Secure Socket Layer?
SSL, or Secure Sockets Layer, is an Internet security protocol that encrypts
data to keep it safe. It was created by Netscape in 1995 to ensure privacy,
authentication, and data integrity in online communications. SSL is the older
version of what we now call TLS (Transport Layer Security).
Websites using SSL/TLS have “HTTPS” in their URL instead of “HTTP.”
How does SSL work?
● Encryption: SSL encrypts data transmitted over the web, ensuring
privacy. If someone intercepts the data, they will see only a jumble of
characters that is nearly impossible to decode.
● Authentication: SSL starts an authentication process called a
handshake between two devices to confirm their identities, making
sure both parties are who they claim to be.
● Data Integrity: SSL digitally signs data to ensure it hasn’t been
tampered with, verifying that the data received is exactly what was
sent by the sender.
Why is SSL Important?
Originally, data on the web was transmitted in plaintext, making it easy for
anyone who intercepted the message to read it. For example, if someone
logged into their email account, their username and password would travel
across the Internet unprotected.
SSL was created to solve this problem and protect user privacy. By encrypting
data between a user and a web server, SSL ensures that anyone who
intercepts the data sees only a scrambled mess of characters. This keeps the
user’s login credentials safe, visible only to the email service.
Additionally, SSL helps prevent cyber attacks by:
● Authenticating Web Servers: Ensuring that users are connecting to
the legitimate website, not a fake one set up by attackers.
● Preventing Data Tampering: Acting like a tamper-proof seal, SSL
ensures that the data sent and received hasn’t been altered during
transit.
Secure Socket Layer Protocols
● SSL Record Protocol
● Handshake Protocol
● Change-Cipher Spec Protocol
● Alert Protocol
SSL Record Protocol
SSL Record provides two services to SSL connection.
● Confidentiality
● Message Integrity
In the SSL Record Protocol application data is divided into fragments. The
fragment is compressed and then encrypted MAC (Message Authentication
Code) generated by algorithms like SHA (Secure Hash Protocol) and MD5
(Message Digest) is appended. After that encryption of the data is done and in
last SSL header is appended to the data.
Handshake Protocol
Handshake Protocol is used to establish sessions. This protocol allows the
client and server to authenticate each other by sending a series of messages
to each other. Handshake protocol uses four phases to complete its cycle.
● Phase-1: In Phase-1 both Client and Server send hello-packets to
each other. In this IP session, cipher suite and protocol version are
exchanged for security purposes.
● Phase-2: Server sends his certificate and Server-key-exchange. The
server end phase-2 by sending the Server-hello-end packet.
● Phase-3: In this phase, Client replies to the server by sending his
certificate and Client-exchange-key.
● Phase-4: In Phase-4 Change-cipher suite occurs and after this the
Handshake Protocol ends.
SSL Handshake Protocol Phases diagrammatic representation
Change-Cipher Protocol
This protocol uses the SSL record protocol. Unless Handshake Protocol is
completed, the SSL record Output will be in a pending state. After the
handshake protocol, the Pending state is converted into the current state.
Change-cipher protocol consists of a single message which is 1 byte in length
and can have only one value. This protocol’s purpose is to cause the pending
state to be copied into the current state.
Alert Protocol
This protocol is used to convey SSL-related alerts to the peer entity. Each
message in this protocol contains 2 bytes.
The level is further classified into two parts:
Warning (level = 1)
This Alert has no impact on the connection between sender and receiver.
Some of them are:
● Bad Certificate: When the received certificate is corrupt.
● No Certificate: When an appropriate certificate is not available.
● Certificate Expired: When a certificate has expired.
● Certificate Unknown: When some other unspecified issue arose in
processing the certificate, rendering it unacceptable.
● Close Notify: It notifies that the sender will no longer send any
messages in the connection.
● Unsupported Certificate: The type of certificate received is not
supported.
● Certificate Revoked: The certificate received is in revocation list.
Fatal Error (level = 2):
This Alert breaks the connection between sender and receiver. The
connection will be stopped, cannot be resumed but can be restarted. Some of
them are :
● Handshake Failure: When the sender is unable to negotiate an
acceptable set of security parameters given the options available.
● Decompression Failure: When the decompression function
receives improper input.
● Illegal Parameters: When a field is out of range or inconsistent with
other fields.
● Bad Record MAC: When an incorrect MAC was received.
● Unexpected Message: When an inappropriate message is received.
The second byte in the Alert protocol describes the error.
Salient Features of Secure Socket Layer
● The advantage of this approach is that the service can be tailored to
the specific needs of the given application.
● Secure Socket Layer was originated by Netscape.
● SSL is designed to make use of TCP to provide reliable end-to-end
secure service.
● This is a two-layered protocol.
Versions of SSL
SSL 1 – Never released due to high insecurity
SSL 2 – Released in 1995
SSL 3 – Released in 1996
TLS 1.0 – Released in 1999
TLS 1.1 – Released in 2006
TLS 1.2 – Released in 2008
TLS 1.3 – Released in 2018
SSL Certificate
SSL (Secure Sockets Layer) certificate is a digital certificate used to secure
and verify the identity of a website or an online service. The certificate is
issued by a trusted third-party called a Certificate Authority (CA), who verifies
the identity of the website or service before issuing the certificate.
The SSL certificate has several important characteristics that make it a
reliable solution for securing online transactions:
● Encryption: The SSL certificate uses encryption algorithms to
secure the communication between the website or service and its
users. This ensures that the sensitive information, such as login
credentials and credit card information, is protected from being
intercepted and read by unauthorized parties.
● Authentication: The SSL certificate verifies the identity of the
website or service, ensuring that users are communicating with the
intended party and not with an impostor. This provides assurance to
users that their information is being transmitted to a trusted entity.
● Integrity: The SSL certificate uses message authentication codes
(MACs) to detect any tampering with the data during transmission.
This ensures that the data being transmitted is not modified in any
way, preserving its integrity.
● Non-repudiation: SSL certificates provide non-repudiation of data,
meaning that the recipient of the data cannot deny having received it.
This is important in situations where the authenticity of the
information needs to be established, such as in e-commerce
transactions.
● Public-key cryptography: SSL certificates use public-key
cryptography for secure key exchange between the client and server.
This allows the client and server to securely exchange encryption
keys, ensuring that the encrypted information can only be decrypted
by the intended recipient.
● Session management: SSL certificates allow for the management
of secure sessions, allowing for the resumption of secure sessions
after interruption. This helps to reduce the overhead of establishing a
new secure connection each time a user accesses a website or
service.
● Certificates issued by trusted CAs: SSL certificates are issued by
trusted CAs, who are responsible for verifying the identity of the
website or service before issuing the certificate. This provides a high
level of trust and assurance to users that the website or service they
are communicating with is authentic and trustworthy.
