JAVA
Information Security: Principles ad Practices.
Write a program to help an analyst decrypt a simple substitution cipher.
Your program should take the ciphertext as input, compute letter frequency
counts, and display these for the analyst. The program should
then allow the analyst to guess a key and display the results of the
corresponding \"decryption\" with the putative key.
BELOW IS WHAT I GOT SO FAR. ANALYST IS NOT GUESSING A KEY OR PUTATIVE
KEY IS NOT COMING OUT.
IF YOU HAVE BETTER PROGRAM, PLEASE IGNORE THE SOURCE BELOW. THANKS.
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
publicclass SubstitutionCipher
{
Map letterFrequencyMap;
Map key;
String ciphertext;
String plaintext;
BufferedReader br;
privatevoid getCiphertext() // get cipher text as input from analyst
{
System.out.println(\"----- Substitution Cipher ----\");
System.out.println(\" Enter the cipher text: \");
br = new BufferedReader(new InputStreamReader(System.in));
try
{
ciphertext = br.readLine();
}
catch(Exception e)
{
System.err.println(\"Exception in cipher text reading \" + e );
e.printStackTrace();
}
ciphertext = ciphertext.toUpperCase();
System.out.println(\"The ciphertext Entered is - \" + ciphertext);
}
privatevoid displayLetterFrequency()
{
letterFrequencyMap = new LinkedHashMap();
for (int i = 0; i < ciphertext.length(); i++)
{
Character ch = ciphertext.charAt(i);
if (!( ch >= \'A\' && ch <=\'Z\')) continue; // check if letter is not in between A to Z
Integer cnt = (Integer) letterFrequencyMap.get(ch);
if(cnt == null)
{
letterFrequencyMap.put(ch,1);
}
else
{
letterFrequencyMap.put(ch,cnt + 1);
}
}
System.out.println(letterFrequencyMap);
}
privatevoid keyGuess()
{
System.out.println(\"Hey Analyst , Guess a key from a to z\");
String putativeKey = null;
try
{
putativeKey = br.readLine();
}
catch(Exception e)
{
System.out.println(\"Excpetion in reading the putative key\");
e.printStackTrace();
}
createKeyMap(putativeKey);
}
privatevoid createKeyMap(String putativeKey)
{
if(putativeKey.length() < 26)
{
System.out.println(\"putative key length is less then 26 letters. Invalid Entry. \");
return;
}
key = new HashMap();
putativeKey = putativeKey.toUpperCase();
for(int j = 0;j
Solution
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
class SubstitutionCipher
{
Map letterFrequencyMap;
Map key;
String ciphertext;
String plaintext;
BufferedReader br;
private void getCiphertext() // get cipher text as input from analyst
{
System.out.println(\"----- Substitution Cipher ----\");
System.out.println(\" Enter the cipher text: \");
br = new BufferedReader(new InputStreamReader(System.in));
try
{
ciphertext = br.readLine();
}
catch(Exception e)
{
System.err.println(\"Exception in cipher text reading \" + e );
e.printStackTrace();
}
ciphertext = ciphertext.toUpperCase();
System.out.println(\.
Interactive Powerpoint_How to Master effective communication
Present an overview of the gene organization in large-genome plants..pdf
1. Present an overview of the gene organization in large-genome plants. What general level of gene
density do plant genomes normally exhibit? What is the composition of the non-gene portions of
the DNA?
Solution
Ans: Total amount of DNA present in nucleus is calle genome. Based on reassociation kinetics,
Generally genome divided into
1. highly repetetive sequence (10%): It is non gene portion, contains 1. Tandem repeats: ex:
Satilite DNA (Mini/ microsatelite DNA) mainly present in centromeric and telomeric regions
(heterochromatin). 2.Dispersed repeats:ex: LINES and SINES
2. moderatly repetative sequence (20%) : Gene families (Homogenous gene family or
heterogenous gene family) Ex: r-RNA gene cluster, Histone gene cluster.
3. non repetative sequence(70%): Almost all structural genes.
repetative sequences mainly present in Hetero chromatin regions, mainly non coding regions.
nonrepetative regions present in euchromatin region, mainly coding regions.
In plants 80% of the genome is repetative.
In 2000, Model plant arbdopsis thaliana was sequenced: Gene density of arbdopsis thaliana was
4-5 Kb/gene. Similar to rice also. Grass genomes are highly variable in size from 410 mb (rice)
to 16000 mb (hexaploid wheat).
