Lab Programs For Information Security Lab 2mw36

1. Consider a file with composite data, substitute the content and transpose the ciphers. #include<stdio.h> #include<stdlib.h> #include<string.h> FILE *src,*dest; FILE *openfile(FILE *fptr,char *name, char *mode) { fptr=fopen(name,mode); if(fptr==NULL) { printf("Unable to open a file \n"); exit(1); } return fptr; } void substitutencrypt() { char str[50],str1[50],ch; printf("\n Enter the input filename to encrypt\n"); scanf("%s",str); src=openfile(src,str,"r"); printf("Enter the output filename to decrypt\n"); scanf("%s",str1); dest=openfile(dest,str1,"w"); ch=fgetc(src); while(ch!=EOF) { fputc(ch+5,dest); printf("%c",ch+5); ch=fgetc(src); } fclose(dest); return; } void substitutdecrypt() { char str[50],str1[50],ch; printf("\n Enter the filename to decrypt \n"); scanf("%s",str); src=openfile(src,str,"r"); printf("\n Enter the filename to encrypt\n");

scanf("%s",str1); dest=openfile(dest,str1,"w"); ch=fgetc(src); while(ch!=EOF) { fputc(ch-5,dest); ch=fgetc(src); } fclose(dest); return; } void transpose() { int i=0,j=0,k=0,count; char ch,str[50],str1[50],msg[50],dmsg[50]; printf(" enter the filename to encrypt \n"); scanf("%s",str); src=openfile(src,str,"r"); printf("enter the filename to transpose\n"); scanf("%s",str1); dest=openfile(dest,str1,"w"); ch=fgetc(src); while(ch!=EOF) { msg[i++]=ch; ch=fgetc(src); } msg[i]='\0'; count=strlen(msg); if(count%2==0) j=count/2; else j=count/2+1; i=0; while(i
dmsg[i]='\0'; printf("\nThe cipher text is\n"); printf("%s",dmsg); fwrite(dmsg,strlen(dmsg),1,dest); fclose(dest); } void transposedecrypt() { int i=0,j,k=-1,l,count; char ch,str[50],str1[50],msg[50],dmsg[50]; printf("\nEnter the filename to decrypt\n"); scanf("%s",str); src=openfile(src,str,"r"); printf("\nEnter the filename for plaintext\n"); scanf("%s",str1); dest=openfile(dest,str1,"w"); ch=fgetc(src); while(ch!=EOF) { dmsg[i++]=ch; ch=fgetc(src); } dmsg[i]='\0'; i=0; count=strlen(dmsg); if(count%2==0) j=count/2; else j=count/2+1; l=j; while(i
printf("Decrypted message\n"); printf("%s",msg); fwrite(msg,strlen(msg),1,dest); fclose(dest); } void main() { int choice; char str[50]; do { printf("\n Enter your choice \n"); printf("1.substitute encryption \n 2.substitute Decryption \n 3.Transpose\n 4. transposedecr\n 5.Exit\n \n"); scanf("%d",&choice); switch(choice) { case 1: substitutencrypt(); break; case 2: substitutdecrypt(); break; case 3: transpose(); break; case 4: transposedecrypt(); break; default: exit(0); } }while(choice>0); } gcc transpose.c ./a.out Enter your choice 1.substitute encryption 2.substitute Decryption 3.Transpose 4. transposedecr 5.Exit 1 Enter the input filename to encrypt f1.c Enter the output filename to decrypt f2.c mjqqt Enter your choice 1.substitute encryption 2.substitute Decryption 3.Transpose 4.transposedecr 5.Exit 3 enter the filename to encrypt f1.c enter the filename to transpose f3.c The cipher text is hloel

Program 3 Apply the RSA algorithm on a text file to produce cipher text file. import java.math.BigInteger ; import java.util.Random ; import java.io.* ; /* RSA.java*/ public class RSA { /** * Bit length of each prime number. */ int primeSize ; /** * Two distinct large prime numbers p and q. */ BigInteger p, q ; /** * Modulus N. */ BigInteger N ; /** *r=(p-1)*(q-1) */ BigInteger r ; /** * Public exponent E and Private exponent D */ BigInteger E, D ; public RSA(){ } /** * Constructor. * * @param primeSize */ public RSA( int primeSize ) { this.primeSize = primeSize ;

Bit length of each prime number.

// Generate two distinct large prime numbers p and q. generatePrimeNumbers() ;

// Generate Public and Private Keys. generatePublirivateKeys() ; /** * Generate two distinct large prime numbers p and q. */ public void generatePrimeNumbers() { p = new BigInteger( primeSize, 10, new Random()) ; do { q = new BigInteger( primeSize, 10, new Random()) ; } while( q.compareTo( p ) == 0 ) ; } /** * Generate Public and Private Keys. */ public void generatePublirivateKeys() { // N = p * q N = p.multiply( q ) ; // r = ( p - 1 ) * ( q - 1 ) r = p.subtract( BigInteger.valueOf( 1 ) ) ; r = r.multiply( q.subtract( BigInteger.valueOf( 1 ) ) ) ; // Choose E, coprime to and less than r do { E = new BigInteger( 2 * primeSize, new Random() ) ; } while( ( E.compareTo( r ) != -1 ) || ( E.gcd( r ).compareTo( BigInteger.valueOf( 1 ) ) != 0)); // Compute D, the inverse of E mod r D = E.modInverse( r ) ; } /** * Encrypts the plaintext (Using Public Key). *

* @param message String containing the plaintext message to be encrypted. * @return The ciphertext as a BigInteger array. */ public BigInteger[] encrypt( String message ) { int i ; byte[] temp = new byte[1] ; byte[] digits = message.getBytes() ; BigInteger[] bigdigits = new BigInteger[digits.length] ; for( i = 0 ; i < bigdigits.length ; i++ ) { temp[0] = digits[i] ; bigdigits[i] = new BigInteger( temp ) ; } BigInteger[] encrypted = new BigInteger[bigdigits.length] ; for( i = 0 ; i < bigdigits.length ; i++ ) encrypted[i] = bigdigits[i].modPow( E, N ) ; return( encrypted ) ; } /** * Get prime number p. * * @return Prime number p. */ public BigInteger getp() { return( p ) ; } /** * Get prime number q. * * @return Prime number q. */ public BigInteger getq() { return( q ) ; }

/** * Get r. * * @return r. */ public BigInteger getr() { return( r ) ; } /** * Get modulus N. * * @return Modulus N. */ public BigInteger getN() { return( N ) ; } /** * Get Public exponent E. * * @return Public exponent E. */ public BigInteger getE() { return( E ) ; } /** * Get Private exponent D. * * @return Private exponent D. */ public BigInteger getD() { return( D ) ; }

}

import java.math.*; import java.io.*; import java.io.FileReader; import java.io.IOException; public class RSAMain{ public static void main(String args[]){ String nhash; BigInteger[] ciphertext = null; BigInteger n = null; BigInteger d = null; StringBuffer input = new StringBuffer(); // Read From File try { BufferedReader br = new BufferedReader(new FileReader("rsa-input.txt")); String sCurrentLine; while ((sCurrentLine = br.readLine()) != null) { input.append(sCurrentLine); } } catch (IOException e) { e.printStackTrace(); } System.out.println(" Input text is :"+input); // Perform RSA Encryption RSA rsa = new RSA( 32 ) ; n=rsa.getN(); // Modulus value d=rsa.getD(); // Exponent value ciphertext = rsa.encrypt(input.toString()) ; // perform RSA Encryption // Convert binary cipherText to string format StringBuffer bf = new StringBuffer(); for( int i = 0 ; i < ciphertext.length ; i++ ) { bf.append( ciphertext[i].toString( 16 ).toUpperCase() ) ; } // convert string buffer to string

String message=bf.toString(); System.out.println("Encrypted text written to rsa-output.txt file"); /* Writing into File */ try { BufferedWriter out = new BufferedWriter(new FileWriter("rsa-output.txt")); out.flush(); out.write(message); // Write the string into file out.close(); } catch (IOException e) { e.printStackTrace(); } } }

Program 4. Develop a mechanism to setup a security channel using Diffie-Hellman Key Exchange between client and server

#include<stdio.h> #include<math.h> void main() { long int q,alpha,Xa,Xb,Ya,Yb,Ka,Kb; printf("Enter a prime number q:\n"); scanf("%ld",&q); printf("Enter the value of alpha:\n"); scanf("%ld",&alpha); printf(" A: Enter a prime number Xa which is less than q:\n"); scanf("%ld",&Xa); printf(" B: Enter a prime number Xb which is less than q:\n"); scanf("%ld",&Xb); Ya=((long int)pow(alpha,Xa))%q; printf(" A sends Ya=%ld to B\n",Ya); Yb=((long int)pow(alpha,Xb))%q; printf(" B sends Yb=%ld to A\n",Yb); Ka=((long int)pow(Yb,Xa))%q; printf(" A calculates secret key Ka=%ld \n",Ka); Kb=((long int)pow(Ya,Xb))%q; printf(" B calculates secret key Kb=%ld \n",Kb); if(Ka==Kb) printf("The keys exchanged by A and B are same"); else printf("The keys exchanged by A and B are not same"); } Output: Enter a prime number q: 7 Enter the value of alpha: 3 A: Enter a prime number Xa which is less than q:5

B: Enter a prime number Xb which is less than q:3 A sends Ya=5 to B B sends Yb=6 to A A calculates secret key Ka=6 B calculates secret key Kb=6 The keys exchanged by A and B are same

Program 7. Using any simulation tool: demonstrate packet filtering firewalls, create the ACL, create VLAN [Subnetting].

Select any component.

Click on CLI to start configuration.

Asg IP address and command prompt(Used to ping)

Before applying any access list ping and make sure two end devices are communicating with each other.

Router1>enable // There are 0-15 different levels of enable. Router1#configure terminal // command used to get into configuration mode

Router1(config)#interface serial 2/0 //Interface is a keyword used to get into any interface followed by the type and number of the interface.

Router1(config-if)#ip address 20.0.0.1 255.0.0.0 // used to assign IP address to any device port.

Router1(config-if)#clock rate 64000 // need to assign a clock rate for router to router communication. It is assigned on the DCE side of the cable. Just point your mouse pointer over the cable if a clock appears then its DCE Router1(config-if)#no shutdown //*** By default all the ports are in shutdown/Inactive state. No shutdown is used to activate

Router1(config-if)#exit // to Router1(config)#interface fastEthernet 2/0 Router1(config-if)#ip address 10.0.0.1 255.0.0.0 Router1(config-if)#exit Router1(config)#ip route 30.0.0.0 0.0.0.0 20.0.0.2 // known as static routing Router1(config)#access-list 25 permit 30.0.0.20 0.0.0.0 // creating a access list Explaination same as above Router2>enable Router2#configure terminal Router2(config)#interface serial 2/0 Router2(config-if)#ip address 20.0.0.2 255.0.0.0 Router2(config-if)#no shutdown Router2(config-if)#exit Router2(config)#interface fastEthernet 2/0 Router2(config-if)#ip address 30.0.0.1 255.0.0.0 Router2(config-if)#exit Router2(config)#ip route 10.0.0.0 0.0.0.0 20.0.0.1 VLAN

Switch>enable Switch#configure terminal Switch(config)#interface fastEthernet 4/0 Switch(config-if)#switchport access vlan 2 Switch(config-if).#exit Switch(config)# // Go into each interface and assign vlans.