Idea and steganography

INTRODUCTION

Steganography is the art and science of encoding hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message. It is a form of security through obscurity.

Demaratus sent a warning about a forthcoming attack to Greece by writing it directly on the wooden backing of a wax tablet before applying its beeswax surface.

The first recorded uses of steganography can be traced back to 440 BC

History1 Wax tablets2

Wax Tablet

INTRODUCTION HISTORY TECHNIQUES APPLICATIONS THANK YOU

Physical

Digital

Physical Steganogr-aphy

| Writing on head | writing with secret ink

Physical steganogra-phy techniques used earlier in history

Modern Steganography Techniques

Digital Steganography

Before steganogra-

hy

After steganogra-

phy

Removing all but two

least significant bits of all

color components

And now text steganography

In this type of steganography we hide the text in the image

International Data Encryption Algorithm

History

Structure

Key making

International Data Encryption Algorithm

OPERATION

IDEA operates on 64-bit blocks using a 128-bit key, and

consists of a series of eight identical

transformations (a round, see the illustration) and an output

transformation (the half-round). Bitwise eXclusive OR (denoted

with a blue circled plus ).⊕ Addition modulo 216

(denoted with a Green boxed plus ).⊞

Multiplication modulo 216+1, where the all-zero Word

(0x0000) is interpreted as 216

(denoted by a red circled dot )⊙

International Data Encryption Algorithm

Key Making

Each round uses six 16-bit sub-keys, while the half-round uses four, a total of 52 for 8.5 rounds.

The first eight sub-keys are extracted directly from the key, with K1 from the first round being the lower sixteen bits.

further groups of eight keys are created by rotating the main key left 25 bits between each group of eight

:

Any question???

1009080706050403020100