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import java.util.Observable;
public class KryptModel extends Observable {
private int key_t;
private int key_s;
private int mod;
private char[][] knownPlain;
private String plain;
private String cipher;
private String method;
private int modInv;
private String status;
private KryptArith myKA=null;
public KryptModel() {
super();
setMethod("TAUSCH");
key_t=1;
key_s=1;
mod=1;
myKA=new KryptArith();
calcModInv();
plain="";
cipher="";
knownPlain=new char[2][2];
knownPlain[0][0]='1';
knownPlain[0][1]='1';
knownPlain[1][0]='1';
knownPlain[1][1]='1';
}
public int calcModInv()
{
try {
modInv=myKA.modInv(key_t, mod);
}
catch (Exception ae) {
status="Calculating mod. Inverse failed";
return 1;
}
status="Calculated mod. Inverse successfully";
setChanged();
notifyObservers();
return 0;
}
public void setkey_t(int t)
{
key_t=t;
status="key t set successfully";
setChanged();
notifyObservers();
}
public void setkey_s(int s)
{
key_s=s;
status="key s set successfully";
setChanged();
notifyObservers();
}
public void setmod(int m)
{
mod=m;
status="modulus m set successfully";
setChanged();
notifyObservers();
}
public void setPlain(String p)
{
plain=p.toLowerCase();
setChanged();
notifyObservers();
}
public void setCipher(String c)
{
cipher=c.toUpperCase();
setChanged();
notifyObservers();
}
public void setMethod(String m)
{
method=m;
setChanged();
notifyObservers();
}
public void setKnownPlain(char p1,char c1, char p2, char c2)
{
knownPlain[0][0]=p1;
knownPlain[1][0]=p2;
knownPlain[0][1]=c1;
knownPlain[1][1]=c2;
status="Known plaintext chars set. p1: "+
knownPlain[0][0]+" p2: "+
knownPlain[1][0]+" c1: "+
knownPlain[0][1]+" c2: "+
knownPlain[1][1];
setChanged();
notifyObservers();
}
public String getStatus() {
return status;
}
public int getkey_t()
{
return key_t;
}
public int getkey_s()
{
return key_s;
}
public int getmod()
{
return mod;
}
public int getModInv()
{
return modInv;
}
public String getplain()
{
return plain;
}
public String getcipher()
{
return cipher;
}
public void encrypt()
{
if (method.equals("TAUSCH"))
{
if ( plain.isEmpty() == false)
{
char[] temp=plain.toCharArray();
int tmp = 0;
for (int i=0;i<temp.length;i++)
{
tmp=(int)(temp[i]);
//tmp-=97;
tmp=((tmp + key_s) * key_t) % mod;
//tmp+=97;
temp[i]=(char)(tmp);
}
setCipher(new String(temp));
status="Encrypted successfully";
}
}
setChanged();
notifyObservers();
}
public void decrypt()
{
if (method.equals("TAUSCH"))
{
if ( cipher.isEmpty() == false)
{
char[] temp=cipher.toLowerCase().toCharArray();
int tmp = 0;
for (int i=0;i<temp.length;i++)
{
tmp=(int)(temp[i]);
//tmp-=97;
tmp= (tmp*modInv - key_s ) % mod;
//tmp+=97;
temp[i]=(char)(tmp);
}
setPlain(new String(temp));
status="Decrypted successfully";
}
}
setChanged();
notifyObservers();
}
public void attack() {
char p1=knownPlain[0][0];
char p2=knownPlain[1][0];
char c1=knownPlain[0][1];
char c2=knownPlain[1][1];
/*
int ci1,ci2,pi1,pi2;
ci1=((int)c1);
ci2=((int)c2);
pi1=((int)p1);
pi2=((int)p2);
*/
try {
key_t=( (c1-c2) * myKA.modInv(p1-p2,mod) )%mod;
key_s = ( ( c1 * myKA.modInv(key_t,mod) ) - p1 ) % mod;
status="Keys found";
}
catch (Exception e) {
status="Could not find keys";
}
setChanged();
notifyObservers();
}
public void genMod() {
setmod(KryptArith.gen8bitPrim());
status="Prime successfully generated";
setChanged();
notifyObservers();
}
}
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