9. CRYPTOLOGY
CRYPTOGRAPHY
CRYPTANALYSIS

10. General Model
of CRYPTOGRAPHIC SYSTEM

11. Types of
ENCRYPTION
SYMMETRIC
Encryption
ASYMMETRIC
Encryption

12. Dear Ali
I have
received
the new
Dear Ali
I have
received
the new

13. Asymmetric Key Encryption

16. Secrecy
Authenticity

17. Transport Layer Security (TLS) and its predecessor, Secure
Sockets Layer (SSL), are cryptographic protocols which are
designed to provide communication security over the Internet.
They use X.509 certificates and hence asymmetric cryptography to
assure the counterparty with whom they are communicating, and to
exchange a symmetric key.
Several versions of the protocols are in widespread use in
applications such as
Web Browsing
Email
Instant Faxing
Instant messaging
Voice-over-IP (VoIP)

19. Types of
Steganography
Pure Secret Key Public Key

21. Reduces the difficulty in key shar i ng.
Doesn’t pr ovi de bet t er secur i t y
because i t i s easy t o ext r act t he
message i f t he unaut hor i zed per son
knows t he embeddi ng met hod.

23. Pr ovi des bet t er secur i t y compar ed
t o Pur e St eganogr aphy
Di f f i cul t y i n shar i ng t he secr et
key. I f t he at t acker knows t he key
i t wi l l be easi er t o decr ypt and
access or i gi nal i nf or mat i on.