From ae0ea09a01b284dd437b7eb73d8deebe00af6fe8 Mon Sep 17 00:00:00 2001 From: Arathy Rose Date: Thu, 21 Mar 2019 08:38:03 +0530 Subject: [PATCH] Fixed issue #120 --- src/lab/exp1/Introduction.html | 436 ++++++++++++++++++--------------- 1 file changed, 242 insertions(+), 194 deletions(-) diff --git a/src/lab/exp1/Introduction.html b/src/lab/exp1/Introduction.html index 84b1577..4ae1425 100644 --- a/src/lab/exp1/Introduction.html +++ b/src/lab/exp1/Introduction.html @@ -1,5 +1,6 @@ + @@ -7,218 +8,265 @@ - + Welcome to Virtual Labs - A MHRD Govt of india Initiative - - - - + + + + - - - - - + + + + + - - + + + -
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Computer Science & Engineering →Cyptography Lab →List Of Experiments

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Introduction

Theory

Objective

Experiment

Manual

Quizzes

Procedure

Further

Feedback
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Breaking the Shift Cipher

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A private-key encryption scheme consists of a set of all possible messages, called the message space M, and three algorithms, namely, -

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  • (a) Gen
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  • (b) Enc
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  • (c) Dec
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The algorithm for key generation Gen is used to choose a key k at random from the set of all possible secert keys, denoted by the key space K.

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The algorithm for encryption Enc takes as inputs the message m and the secret key k and outputs the ciphertext c.

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The algorithm for decryption Dec inputs the ciphertext c and the key k and outputs the message m.

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About the experiment:

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Apparently, the system is easily broken if the total number of distinct secret keys is small, that is the key space K is small.

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In this experiment, we work with a well-known historical encryption -scheme, namely the shift cipher, that has a very small key space.

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Your task is to break the shift cipher. Specifically, given (only) -the ciphertext in some instance of a shift cipher, you need to find the -plaintext and the secret key.

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