Secure socket layer working

SSL working
102/09/12
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Contents:
202/09/12
 Cryptography and Secure Socket Layer
(SSL)
 Establishment of Secured connection for “Encryption”
 Briefing on Asymmetric Encryption algorithms

Cryptography:
302/09/12
 Security and Integrity
 Encryption helps in achieving this.
 SSL is one such type of protocols. Its two main
functions are:
 Encryption
 Identification

Few terms:
 Certificate:
- It is used to authenticate the website.
- Issued by Certificate Authority (CA).
- Mainly contains:
 Public Key
 Digital Signature
 Hashing:
- It is a process that compresses text to a single number.
- Used in a certificate and in SSL handshaking.
602/09/12

Data Transfer:
702/09/12
 Asymmetric Data Transfer
- Used in handshaking
- Two Keys are involved:
 Public Key: It is used to encrypt.
 Private Key: It is used to decrypt.
 Symmetric Data Transfer
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Used in application data transfer.
Same key is used in encryption & decryption.

SSL Protocol Design
SSL 3.0
Design
Handshaking
Protocol
Record
Protocol
Handshaking Protocol Functionalities:
- Negotiates the cipher suite,
- Authenticates the server and, optionally, the client and
- Establishes the session keys.
The Record Protocol:
- Secures the application data with the session key,
- Verifiestheapplicationdata’s integrityandorigin.

SSL DESIGN architecture
The handshaking Protocol actually has
three sub-protocols.
The“ChangeCipherProtocol”informsthe
peer about the set of keys change request.
The“alert”protocol notifiesthepeer about
the cause of protocol failure, It is not
normally sent during the handshake
protocol.
Diagram by, the computer science and Engineering Department,
The Ohio State University.

Key exchange algorithms
- Anonymous Diffie-Hellman (DH)
- Ephemeral Diffie-Hellman (DHE)
Using DH or DHE,no need to send a server or client certification message, certificate request
or verify messages; instead, server sends a server key-exchange message that provide
information to encrypt the premaster secret.
An option to negotiate a pre-shared key PSK exists.

Encryption Algorithms:
Key Cipher Hash
RSA DES HAC- MD5
Diffie Hellman Triple DES HMAC- SHA
AES
RC4
A B
Key Cipher Hash
RSA DES HAC- MD5
Diffie Hellman Triple DES HMAC- SHA
AES
RC4
1502/09/12
Computers agree how to encrypt !

The Problem
The Problem
•securing client-server
communications over
the internet.

Solution
Solution
•Setup Some
Security (TLS)

Asymmetric Key Cryptography:
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Diffi Hellman algorithm
Rivest, Shamir and Adleman (RSA) algorithm
2802/09/12

Symmetric key Cryptography:
2902/09/12
 Used for encryption of data.
 Substitution/Transposition/Simple round ciphers.
 Modern round ciphers: DES, Triple DES, AES

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