CRYPTOGRAPHY in network security Majeti Srividya CS 555

CRYPTOGRAPHYin network security

Majeti SrividyaCS 555

WHY WE NEED CRYPTOGRAPHY

Goal: Secure Communication

Confidentiality- read by someone else?

Authentication-Trusting the sender of message ?

Integrity-is the message unchanged?

Non-Repudiation-can the sender refute the message?

WHAT IS CRYPTOGRAPHY

Encryption

Decryption

Algorithm Eg: DES, RSA

Key Symmetric Asymmetric

ALGORITHMS:

http://www.mcpressonline.com/articles/images/2002/Encryption%20GuideV4--04230700.jpg



TECHNIQUES FOR CRYPTOGRAPHYSubstitution

Transposition

Combinational

http://www.infosectoday.com/Articles/Intro_to_Cryptography/CryptoFig04.jpg

http://upload.wikimedia.org/wikipedia/commons/2/2a/ROT13.png







EXAMPLE: SSL/TLS Secure Socket Layer/Transport Layer Security

Provides communication security between the transport layers of two hosts

Provides a secure tunnel between two hosts

Widely used to secure web shopping

Secure Socket Layer (SSL)

SSL SUB-PROTOCOLS

Handshake Protocol

Record Protocol

Alert Protocol

SSL HANDSHAKE PROCESS

SSL/TLS HANDSHAKE

http://minnie.tuhs.org/NetSec/Slides/week7.html



SSL RECORD PROTOCOL

SSL ALERT PROTOCOLAlert Description

Unexpected message An inappropriate message was received.

Bad record MAC A message is received without a correct MAC.

Decompression failure

The decompression function received an improper input.

Handshake failure Sender was unable to negotiate an acceptable set of security parameters from the available options.

Illegal parameters A field in the handshake message was out of range or was inconsistent with the other fields.

REFERENCES: http://www.infosectoday.com/Articles/Intro_to_Cryptography/CryptoFig04.jpg




http://www.google.com/imgres?q=ssl+handshake+process&um=1&hl=en&safe=off&sa=N&tbo=d&biw=1280&bih=880&tbm=isch&tbnid=hjVHl9FJ0S3AxM:&imgrefurl=http://blog.doteasy.com/2009/06/15/the-good-to-knows-of-ssl-and-ssl-certificates/&docid=XCmn9z-nYi-nVM&imgurl=http://blog.doteasy.com/wp-content/uploads/2009/06/ssl_handshake.png&w=440&h=463&ei=vmi1UIS_DanN0AG4sIHwDQ&zoom=1&iact=rc&dur=463&sig=100602218594818410526&page=1&tbnh=138&tbnw=131&start=0&ndsp=37&ved=1t:429,r:0,s:0,i:87&tx=76&ty=71

http://www.google.com/imgres?q=secure+socket+layer+protocol&um=1&hl=en&safe=off&tbo=d&biw=1280&bih=880&tbm=isch&tbnid=ruin1g2LwW3E2M:&imgrefurl=http://httpd.apache.org/docs/2.2/ssl/ssl_intro.html&docid=Pde5UpBQSvNfJM&imgurl=http://httpd.apache.org/docs/2.2/images/ssl_intro_fig2.gif&w=428&h=217&ei=z2m1UN73JsuH0QHu_oGYDg&zoom=1&iact=hc&vpx=506&vpy=477&dur=810&hovh=160&hovw=315&tx=96&ty=73&sig=100602218594818410526&page=1&tbnh=131&tbnw=258&start=0&ndsp=31&ved=1t:429,r:15,s:0,i:129

http://www.google.com/imgres?q=ssl+record+protocol&num=10&um=1&hl=en&safe=off&tbo=d&biw=1280&bih=880&tbm=isch&tbnid=XIMmxl7MuSmcoM:&imgrefurl=http://www.windowsecurity.com/articles/secure_socket_layer.html&docid=jpYEvb0YS599rM&imgurl=http://www.windowsecurity.com/img/upl/rysunek3a1026827782453.jpg&w=575&h=361&ei=E2u1UPmwCYW_0QGVy4CQCg&zoom=1&iact=rc&dur=0&sig=100602218594818410526&sqi=2&page=1&tbnh=128&tbnw=204&start=0&ndsp=18&ved=1t:429,r:1,s:0,i:87&tx=266&ty=255






















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CRYPTOGRAPHY in network security Majeti Srividya CS 555