# Importance Of Cryptography

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CHAPTER 1 INTRODUCTION 1.1 Cryptography The word cryptography is derived from the Greek words Cryptos meaning cover and grafia meaning writing [1] defining it as covered writing. In image cryptography the information is hidden exclusively in images. Cryptography is the art and science of secret communication .It is the practice of encoding/embedding secret information in a manner such that the existence of the information is invisible. The original files can be referred to as cover text, cover image, or cover audio. After inserting the secret message it is referred to as Crypto-medium. A Crypto-key is used for hiding/encoding process to restrict detection or extraction of the embedded data [2]. More generally, it is about constructing and…show more content…
There are several protocols that offer provable properties, primarily those designed for use with the OTP. The problem with proving properties of protocols under other schemes is that the mathematics is extremely complex for the RSA, and there is no sound mathematical basis for the DES. Much research is under way at this time in the field of protocol analysis and verification, and it is likely that once this field stabilizes, cryptographic protocols will follow…show more content…
By simple calculation, if only capital letters were allowed in a password, it would take .26 seconds to check all the one letter passwords, 6.76 seconds to check all the 2 letter passwords, 4570 seconds for the 4 letter passwords, and by the time we got to 8 letter passwords, it would take about 2*10**9 seconds (24169 days, over 66 years). For passwords allowing lower case letters, numbers, and special symbols, this goes up considerably. Studies over the years have consistently indicated that key selection by those without a knowledge of protection is very poor. In a recent study 21% of the users on a computer system had 1 character passwords, with up to 85% having passwords of 1/2 the maximum allowable length, and 92% having passwords of 4 characters or less. These results are quite typical, and dramatically demonstrate that 92% of all passwords could be guessed on a typical system in just over an