Chapter 11
Dierential Crypt Analysis
February 15, 2010
11
Dierential crypt-analysis (DCA) is a general form of cryptanalysis applicable primarily to block ciphers, but can also be applicable to stream ciphers
and cryptographic hash functions. With respect
Chapter 12
Linear Crypt Analysis
February 15, 2010
12
Similar to Dierential Crypt Analysis (DCA) Linear Crypt Analysis (LCA)
is a technique for attacking encryption algorithms of many rounds with subkeys entering linearly in each round. Like DCA it exploi
Chapter 9
Factorisation and Discrete Logarithms
Using a Factor Base
February 15, 2010
9
The two intractable problems which are at the heart of public key cryptosystems, are the infeasibility of factorising large integers and of solving the
discrete logari
Chapter 10
Elliptic Curves in Cryptography
February 15, 2010
10
Elliptic Curves (ECs) can be used as an alternative to modular arithmetic
in all applications based on the Discrete Logarithm (DL) problem.
The DL problem is:
Given n, b, ; nd x from b = x mo
Chapter 7
Random Numbers
February 15, 2010
7
In the following random numbers and random sequences are treated as two
manifestations of the same thing. A series of random numbers strung together is considered to be a random sequence. A random sequence chop
Chapter 6
Hash Functions
February 15, 2010
6
Hash functions have been used in computing from the earliest days, and have
a particular relevance to cryptography - in particular to digital signatures.
Hash functions are also sometimes known as message diges
Chapter 8
Factorising and Finding Discrete Logarithms
Simple Techniques
February 15, 2010
8
The security of many cryptographic techniques rests on:
1. The infeasibility of factorising large integers (Example: RSA, Rabin
Encryption)
2. The infeasibility of
Chapter 4
Public Key Cryptology - Part I
February 15, 2010
4
The concept of public key cryptology (PKC) emerged in the early 1970s in
the British Governments communications center CESG, Cheltenham. (See
J.H.Ellis The Possibility of Secure Non-Secret Digit
Chapter 1
Introduction and Background
February 15, 2010
1
The notes forming this collection are essentially those given out to third
and fourth year undergraduate students of a course on Cryptology (Cryptography plus Crypt-analysis; of constructing crypto
Chapter 3
Modular Arithmetic
February 15, 2010
3
In computers information is represented digitally, and nearly always in binary.
It can be considered to be integers and manipulated as such. Arithmetical operations often change the length of the quantities
Chapter 2
Symmetric Encryption Algorithms
February 15, 2010
2
The term symmetric means that the same key used to encrypt is used
decrypt.
In the widest sense all pre-PKC encryption algorithms are symmetric,
although their keys may be very dierent in form.
Chapter 5
Public Key Cryptology - Part II
February 15, 2010
5
The basic concepts of PKC become widely known in the later 1970s and
many schemes involving its use have been developed since then. Most of
these were based on modular arithmetic (see Chapter 3