transpositioncipher.java

用java编写的简单加密程序

Appendix 1: Java source code for TranspositionCipher.java

/*
  Wrtten by:  H Yu  
  First written:05/11/07
  Last modified:09/11/07
*/


import sheffield.*;
public class TranspositionCipher{
  public static void main(String[] args){
	EasyReader keyboard=new EasyReader();
	EasyReader inputfiles=new EasyReader("plain.txt");
	EasyWriter screen=new EasyWriter();
	int lc,lp,lk; 
	String plaintext=new String();
    
        //input cipherkey from the keyboard and put the letters into an array
        String cipherkey=keyboard.readString("Please input the cipherkey: ");    
	lk=cipherkey.length();
	String[] k=new String[lk];
	for(int i=0;i<lk;i++) {
		String ck= cipherkey.substring(i, i+1);
		k[i]=ck;                   
	}

        //check if the cipher key is legal
	boolean illegal=false;
        for(int i=0;i<lk-1;i++){
		for(int j=i+1;j<lk;j++){
			boolean eq=k[i].equals(k[j]);
			if(eq){					
 				screen.println("The key should't be repeated!");
				illegal=true;
			}
		}  
    	}
	if(!illegal){

		//readin plaintext from the plain.txt
		while(!inputfiles.eof()){   
			plaintext+=inputfiles.readString().trim()+' ';
		} 
		plaintext=plaintext.trim()+' '; 

		//display the plaintext
		screen.println();
		screen.println("The plaintext is: ");
		screen.println(plaintext);
    
		//creat the matrix of the plaintext as the order of cipher key
		lp= plaintext.length();
		if(lp%lk==0)
			lc=lp/lk;
		else
			lc=lp/lk+1;
		String[][] s=new String[lk][lc];
		String[] temp=new String[lc];
		String tempk;
		for(int i=0;i<lp;i++) {
			String cp= plaintext.substring(i, i+1);	              
			int r=i%lk,c=i/lk;
			s[r][c]=cp;
		}

		//add random letters 
		int ln=lp%lk;
		for(int i=ln;i<lk;i++){
			double a=Math.random();
			a=a*100%26+97;      
			s[i][lc-1]=s[i][lc-1].valueOf((char)a);
		}
			
		//display the matrix of the plaintext 
		screen.println();
		screen.println("The matrix of the plaintext is:");
		for(int j=0;j<lc;j++){
			for(int t=0;t<lk;t++){
				screen.print("\t"+" "+s[t][j]);
			}
			screen.println();
		}
		screen.println();
             
		//reorder the cipher key and plaintext alphabetically
		for(int i=0;i<lk-1;i++){
			for(int j=i+1;j<lk;j++){
				int comp=k[i].compareTo(k[j]);
				if(comp>0){
					tempk=k[i];
					k[i]=k[j];
					k[j]=tempk;
					for(int t=0;t<lc;t++){
						temp[t]=s[i][t];
						s[i][t]=s[j][t];
						s[j][t]=temp[t];
					}
				}
			}
		}
    
		//display the the cipher key alphabetically and the ciphertext 
		screen.println("The ordered matrix with the key is:");
		for(int t=0;t<lk;t++){
			screen.print("\t"+" "+k[t]);
		}
		screen.println();
		int number=1;
		for(int t=0;t<lk;t++){
			screen.print("\t"+"("+number+")");
			number++;
		}
		screen.println();  
		for(int j=0;j<lc;j++){
			for(int t=0;t<lk;t++){
				screen.print("\t"+" "+s[t][j]);
			}
			screen.println();
		}   

		//display the cipher text to the screen in upper case
		screen.println();
		screen.println("The cipher text is: ");
		for(int t=0;t<lk;t++){
			for(int j=0;j<lc;j++){
				screen.print(s[t][j].toUpperCase());
			}
		}
		screen.println();
	}
  }
}