Network security and cryptography

Network Security &

Role of Cryptography

ByRaj Kumar Rampelli

Need for Network security Classification of Network Attacks

◦ Possible Attacks

Security Features Security Mechanism: Cryptography Types of Encryption-Decryption techniques

◦ Symmetric: Shared Key Type◦ Asymmetric: Public/Private Key Type

Public Key Infrastructure Digital Signature Public Key Infrastructure implementation and its factors

◦ Generation of key pair◦ Obtain Digital certificate◦ Encryption/Decryption analysis◦ Digital certificate role

Conclusion

Outline

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What is a Network ?◦ Data Carrier

Data ?◦ Anything which conveys something between

1st person (sender/receiver) and 2nd person (receiver/sender)

Categories of Data ?◦ Normal◦ Confidential Data can’t be enclosed to 3rd person.

Goal ?◦ Protection of DATA i.e. Information Security.◦ Preventing compromise or loss of DATA from unauthorized

access

Need for Network Security

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What is Network Attack ?◦ An action that compromises the security of DATA

Categories of Attacks◦ Passive

Learn from DATA and make use of system information Do not alter the DATA Very difficult to identify the attack Ex: Eavesdropping (Interception)

◦ Active Modifies the DATA Ex: Denial of Service

Possible Attacks◦ Interruption◦ Interception◦ Modification◦ Fabrication

Classification of Attacks

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Normal Flow

Interruption

◦ Attack on “availability” Disconnection of a wireless or wired internet

connection Unavailability of a particular web site Inability to access any web site

Possible Attacks

Sender ReceiverDisturb

Sender Receiver

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Interception (No Privacy)

◦ Attack on “confidentiality”◦ Packet Analyzer software

Intercept and log traffic passing over a network Captures each Packet and decodes the data Ex: Microsoft Network Monitor

◦ Man in the middle attack◦ Wiretapping: capture the data◦ Intruder can be a person or a program or a computer

Possible Attacks (cont.)

Sender Receiver

Intruder

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Modification◦ Attacker modifies the data sent by the sender◦ Gain access to a system and make changes

Alter programs so that it performs differently◦ Attack on “Integrity”

Fabrication◦ Attacker acts like Sender◦ Gain access to a person’s email and sending

messages◦ Attack on “Authenticity”◦ Lack of mutual authentication

Possible Attacks (cont.)

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A Transaction/Communication (or a service) is secure if and only if the following security features are provided◦ Confidentiality◦ Integrity◦ Authenticity (Mutual Authentication)◦ Non-repudiation

Cryptography◦ Symmetric key Cryptography◦ Public Key Infrastructure

Security Features

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Cryptography

Services•Provide security features

Symmetric Key Cryptography

•Data Encryption

Standard (DES)•Triple DES

•Advanced ES

Public Key Infrastructure•Public-Private

Key•RSA•ECC

Encryption and

Decryption•Cypher Text

Digital Signature

Digital Certificate

Security Mechanism: Cryptography

String of information that binds the unique identifier of each user to his/her

corresponding public key.

A mathematical scheme for demonstrating the authenticity, non-repudiation and integrity of

a digital message

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Symmetric Key scenario

Public-Private Key scenario

Encryption-Decryption Techniques

Sender (plain text) SK(plain text)

Cipher Text (Encrypted

text)

Receiver SK(Cipher text) Plain

text

Sender (plain text) PubKey(plain

text)

Cipher Text (Encrypted

text)

Receiver PrivKey(Cipher text)

Plain text

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• Generation of Public-Private key pair

• Generation of certificate request message

• Receive and store digital certificates

• Encryption and Decryption• Generation and verification of

digital signature message• Verification of Digital certificate

Performance factors at client

PKI Implementation

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Generate public and private key pair at client Check the following details using different

Public Key Cryptography (PKC) algorithms◦ Time taken for key pair generation◦ Storage space required for storing the key pair◦ Repeat above two steps by changing the key size in

the algorithm◦ Analyze the results and choose optimal algorithm

suitable for your application. PKC algorithms

◦ RSA◦ ECC

Performance factor-1:Generation of Key Pair

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Generate certificate request message (CRM) using public-private key pair

Apply for new Digital Certificate◦ Send CRM and user/app credentials to Certificate

Authority (CA) CA verifies the requester credentials

◦ Approves/Rejects the application◦ If approved,

Generate Digital Certificate using requester credential with public key information

Store it in Digital certificate data base locally Send Digital certificate to requester

Receive Digital certificate from CA and store locally.

Performance factor-2:Obtain Digital certificate

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String of information that binds the unique identifier of each client to his/her corresponding public key.

Pre-requite for obtaining Digital certificate◦ Generate public-private key pair locally◦ Generate certificate request message

Digital certificate used to authenticate server credentials during mutual authentication process

Mutual authentication process:◦ a client authenticating themselves to a server and that server

authenticating itself to the user in such a way that both parties are assured of the others' identity [wiki]

Authenticating an entity using its Digital certificate:◦ Check the validity period of certificate◦ Verify the digital signature of CA on the certificate using CA’s

public key

What is Digital certificate

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Client encrypts the message using server’s public key The time taken for encryption of fixed size message

◦ Using server’s ECC public key◦ Using server’s RSA public key◦ Analyze the results.

Client decrypts the received message (from server) using client’s private key

The time taken for decryption of fixed size message◦ Using client’s ECC private key◦ Using client’s RSA private key◦ Analyze the results.

Performance factor-3:Encryption of Data at client

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A valid digital signature gives a recipient reason to believe that the message was created by a known sender (Authenticity), such that the sender cannot deny having sent the

message (Non-repudiation) and that the message was not altered in transit (Integrity).

Performance factor-4:Digital signature generation & verification

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A method to Secure “Data transactions” between users is needed◦ Should ensure all desired security features for any

transaction. Cryptography: collections of standards/techniques for

securing the Data.◦ PKI ensures all security features

As the key size increases, the more difficult to crack the data.

Analyze PKI Implementation factors using different cryptographic algorithms with different key sizes

Digital certificate: Mainly used for authenticity Digital signature: Mainly used for Integrity of data

Conclusion

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THANK YOU

Have a Look at: My PPTs: http://www.slideshare.net/rampalliraj/

My Tech Blog:

http://practicepeople.blogspot.in/

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