SSL (Secure Sockets Layer) is a protocol that provides secure communication between a web browser and server. It provides authentication of the server and encryption of data for confidentiality. SSL was developed by Netscape in 1994 and is now implemented as TLS (Transport Layer Security). The SSL/TLS handshake establishes an encrypted connection in a four step process using messages like client hello, server hello, and server key exchange.

1. BABA GHULAM SHAH BADSHAH
UNIVERSITY
12/9/2016
1
AFROZ BGSBU
NAME :- AFROZ HAIDER
ROLL NO:- 08-MCA-2014
TOPIC NAME:-SECURE SOCKET LAYER(SSL)
PRESENTED TO:-
DR.SANJAY JAMWAL
COURSE TITLE:- CRYPTOGRAPHY AND
NETWORK SECURITY

2. • It is an Internet protocol for secure exchange of
information between a web browser and a web
server
• It provides
▫ Authentication
▫ Confidentiality
• Developed by Netscape Corporation in 1994
• Currently comes in three versions : 2, 3 and 3.1
2

3. 3

4. Application Layer
Transport Layer
Internet Layer
Data Link Layer
Physical Layer
SSL Layer
4

5. X
L5 data
010101010100010101010010
Transmission medium
H4L5 data
H3L4 data
Application
Transport
Internet
Physical
H2L3 data Data Link
Y
L5 data
010101010100010101010010
H4L5 data
H3L4 data
H2L3 data
5

6. X
L5 data
010101010100010101010010
Transmission medium
H4L5 data
H3L4 data
Application
Transport
Internet
Physical
L5 data SSLSH
H2L3 data Data Link
Y
L5 data
010101010100010101010010
H4L5 data
H3L4 data
L5 data SH
H2L3 data
6

7. 7

8. 1 • Handshake protocol
2 • Record protocol
3 • Change Cipher protocol
4 • Alert protocol
8

9. Type Length Content
1 byte 3 bytes 1 or more bytes
Message Format
9

10. Message Type Parameters
Hello request None
Client hello Version, Random number, Session id, Cipher suite,
Compression method
Server hello Version, Random number, Session id, Cipher suite,
Compression method
Certificate Chain of X.509V3 certificates
Server key exchange Parameters, signature
Certificate request Type, authorities
Server hello done None
Certificate verify Signature
Client key exchange Parameters, signature
Finished Hash value
10

11. 1
• Establish security capabilities
2
• Server authentication and key exchange
3
• Client authentication and key exchange
4
• Finish
11

12. • Used to initiate logical connection and establish
security capabilities.
• Consists of two messages
▫ Client hello
▫ Server hello
12

13. Web
Browser
Web
Server
Step 1: Client hello
Step 2: Server hello
13

14. • Identifies highest version of SSL that client can supportVersion
• 32 bit date time field
• 28 byte random number
Random
• Variable length session identifier
• Can be zero (new session) or non zero (connection exists)
Session id
• Contains list of cryptographic algorithms supported by the
clientCipher suite
• Contains list of compression algorithms supported by the
client
Compression
method
14

15. • Identifies lower of version suggested by client and
highest supported by serverVersion
• Same structure as that in client hello
• Random value independent of client’s value
Random
• Uses same value if client sends non zero value
• Otherwise creates new session id
Session id
• Contains single cipher suite which server selects from
the list sent by clientCipher suite
• Contains single compression algorithm which server
selects from the list sent by client
Compression
method
15

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Web
Browser
Web
ServerStep 2: Server key exchange
Step 3: Certificate request
Step 4: Server hello done
Step 1: Certificate

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• Server sends its Digital certificate
• Helps the to authenticateCertificate
• Sent only if the certificate does not contain enough information
to complete the key exchange
Server key
exchange
• Sent if the client needs to authenticate itself
Certificate
request
• Sent to indicate that the server is finished its part of the key
exchange
• after sending this message the server waits for client response
Server
hello done

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Web
Browser
Web
Server
Step 1: Certificate
Step 2: Client key exchange
Step 3: Certificate verify

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• will send a certificate message or a no certificate alertCertificate
• always sent
• RSA encrypted pre-master secret
Client key
exchange
• sent only if the client sent a certificate
• provides client authentication
• contains signed hash of all the previous handshake
messages
Certificate
verify

20. 20
Web
Browser
Web
Server
Step 1: Change cipher specs
Step2 : Finished
Step 3: Change cipher specs
Step 4: Finished

21. • Provide two services for SSL connections:
Confidentiality: by encrypting application data.
Message Integrity: by computing MAC over the
compressed data.
• Can be utilized by some upper-layer protocols
of SSL.

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≤ 214 bytes
(optional; default: null)

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IF THE ERROR IS FATAL ,BOTH THE PARTIES IMMEDIATELY
CLOSE THE CONNECTION.BOTH THE PARTIES ALSO THE SESSION
IDENTIFIERS,SECRET AND KEYS ASSOCAITED WITH THIS
CONNECTION BEFORE IT IS TERMOINATED
WHEN EITHER THE CLIENT OR SERVER DETECTS AN ERROR
THE DETECTING PARTY SENDS AN ALERT
MESSAGE TO THE OTHER PARTY.
SEVERITY
1 BYTE
CAUSE
2 BYTE
ALERT PROTOCOL MESSAGE FORMAT

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Warning or fatal
close_notify(0),
unexpected_message(10),
bad_record_mac(20),
decryption_failed(21),
record_overflow(22),
decompression_failure(30),
handshake_failure(40),
bad_certificate(42),
unsupported_certificate(43),
certificate_revoked(44),
certificate_expired(45),
certificate_unknown(46),
illegal_parameter(47),
unknown_ca(48),
access_denied(49),
decode_error(50),
decrypt_error(51),
export_restriction(60),
protocol_version(70),
insufficient_security(71),
internal_error(80),
user_canceled(90),
no_renegotiation(100),

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Always fatal
unexpected_messages
bad_record_mac
decompression_failure
handshake_failure
illegal_parameter

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Remaining alerts
close_notify
no_certificate
bad_certificate
unsupported_certificate
certificate_revoked
certificate_expired
certificate_unknown

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Authentication of server
– How does client know who they are dealing with?
Information integrity
– How do we know third party has not altered data en
route?
Bob’s web
siteAlice thinks she is at Bob’s site, but Darth is
spoofing it
Bob’s web
siteAddress information
Change so item shipped to Darth

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There are several versions of the SSL protocol
defined. The latest version, the Transport
Layer Security Protocol (TLS), is based on
SSL 3.0
SSL Version 1.0
SSL Version 2.0
SSL Version 3.0
TLS Version 1.0
TLS Version 1.0 with SSL Version 3.0

30. 30
www.aiub.edu

31. 31
www.gmail.com

32. 32
www.varsityadmission.com

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 https://www.digicert.com/ssl.htm
 http://www.webopedia.com/TERM/S/SSL.html
 http://en.wikipedia.org/wiki/Transport_Layer_Security

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