Network Security & Cryptography
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Transcript of Network Security & Cryptography
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Cryptography: An Innovative Technique for Information
Security
HIMANSHU GUPTA, FACULTY MEMBER, AMITY UNIVERSITY
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Security Attacks
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Security Attacks
Informationsource
Informationdestination
Normal Flow
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Security Attacks
Informationsource
Informationdestination
Interruption
• Attack on availability
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Security Attacks
Informationsource
Informationdestination
Interception
• Attack on confidentiality
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Security Attacks
Informationsource
Informationdestination
Modification
• Attack on integrity
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Security Attacks
Informationsource
Informationdestination
Fabrication
• Attack on authenticity
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Classify Security Attacks
passive attacks - eavesdropping on, or monitoring of, transmissions to:
obtain message contents, ormonitor traffic flows
active attacks – modification of data stream to:
masquerade of one entity as some otherreplay previous messagesmodify messages in transitdenial of service
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Security Attacks
Release of message contents
Trafficanalysis
• eavesdropping, monitoring transmissions
Passive threats
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Passive Attacks
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Security Attacks
Masquerade Denial ofservice
• some modification of the data stream
Active threats
Replay Modification of message contents
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Active Attacks
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Security Services
Confidentiality – protection from passive attacks
Authentication – you are who you say you are
Integrity – received as sent, no modifications, insertions, shuffling or replays
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Security Services
Nonrepudiation – can’t deny a message was sent or received
Access Control – ability to limit and control access to host systems and apps
Availability – attacks affecting loss or reduction on availability
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Network Security Model
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Cryptography
Cryptography -- from the Greek for “secret writing” -- is the mathematical “scrambling” of data so that only someone with the necessary key can “unscramble” it.
Cryptography allows secure transmission of private information over insecure channels (for example packet-switched networks).
Cryptography also allows secure storage of sensitive data on any computer.
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The language of cryptography
symmetric key crypto: sender, receiver keys identicalpublic-key crypto: encryption key public, decryption
key secret (private)
plaintext plaintextciphertext
KA
encryptionalgorithm
decryption algorithm
KB
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Public-Private key Cryptography
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Secret/Symmetric-key Cryptography
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Secure Communication over Insecure Medium
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RSA Encryption Algorithm
For example. make p = 7and q = 13
We then calculate N = 7∗13 = 91 and (p−1)(q−1) = 72
We next select ke relatively prime to 72 and< 72, yielding 5
Finally,we calculate kd such that ke*kd mod 72 = 1, yielding 29
We how have our keys
Public key, ke, N = 5, 91
Private key, kd , N = 29, 91
Encrypting the message 69 with the public key results in the cyphertext 62
Cyphertext can be decoded with the private key
Public key can be distributed in cleartext to anyone who wants to communicate with holder of public key
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Encryption and Decryption using RSA Asymmetric Cryptography
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What is a Firewall?
a choke point of control and monitoring interconnects networks with differing trustimposes restrictions on network services
only authorized traffic is allowed
auditing and controlling accesscan implement alarms for abnormal behavior
is itself immune to penetrationprovides perimeter defence
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Firewall: Technical Concept
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Firewall ConfigurationsFirewall Configurations
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Thank You!!!!
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Have A Nice Week!!!