2. CRYPTOGRAPHY
Cryptography is a method of protecting information
and communications through the use of codes so that
only those for whom the information is intended can
read and process it. The pre-fix "crypt" means
"hidden" or "vault" and the suffix "graph" stands for
"writing."
3. CRYPTOGRAPHY TECHNIQUES
Cryptography techniques
Cryptography is closely related to the disciplines
of cryptology and cryptanalysis. It includes techniques
such as microdots, merging words with images, and other
ways to hide information in storage or transit. However, in
today's computer-centric world, cryptography is most often
associated with scrambling plaintext (ordinary text,
sometimes referred to as clear text) into cipher text (a
process called encryption), then back again (known as
decryption). Individuals who practice this field are known
as cryptographers.
4. MODERN CRYPTOGRAPHY
Modern cryptography concerns itself with the following four
objectives:
Confidentiality: the information cannot be understood by
anyone for whom it was unintended
Integrity: the information cannot be altered in storage or
transit between sender and intended receiver without the
alteration being detected
Non-repudiation: the creator/sender of the information
cannot deny at a later stage his or her intentions in the
creation or transmission of the information
Authentication: the sender and receiver can confirm each
other's identity and the origin/destination of the
information
5. BASIC CONCEPTS
Cryptosystem, plaintext, cipher text, key
Examples of simple cryptosystems
To publish or not to publish?
Secret and open research in cryptology
Software vs. hardware implementations of
cryptography
Evolution of cryptography and cryptanalysis.
6. Consider two parties Alice and Bob. Now, Alice wants to
send a message m to Bob over a secure channel.
So, what happens is as follows.
The sender’s message or sometimes called the Plaintext, is
converted into an unreadable form using a Key k. The
resultant text obtained is called the Cipher text. This
process is known as Encryption. At the time of receival, the
Cipher text is converted back into the plaintext using the
same Key k, so that it can be read by the receiver. This
process is known as Decryption.
Alice (Sender) Bob (Receiver) C = E (m, k) ----> m = D (C,
k)
7. IMPLEMENTATION OF SECURITY
SERVICES
Classical (symmetric) vs. public key (asymmetric)
cryptosystems
Trapdoor one-way functions - main components of public
key cryptosystems
Features required from today's ciphers
Implementing security services using cryptographic
transformations
Block vs. stream ciphers
Measures of the cipher strength
8. KEY MANAGEMENT
Session keys and key encrypting keys
Exchange of keys using Key Distribution Center
The Diffie-Hellman key exchange protocol
Exchange of symmetric keys using public key
cryptosystems
Generation and registration of the public key pair
Concept of a public key certificate
Formats of certificates
Hierarchy of Certification Authorities - Public Key
Infrastructure
Certificate revocation
9. SECURE INTERNET PROTOCOL
Secure electronic mail
S/MIME
Open PGP
Secure WWW
SSL
Secure payment card protocols
Secure virtual private networks
IPSec
