function do_solve()
  {  	
    var permit="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    var trans =[];
        
    var ct,pt,key,pack,buffer;    
    var j,k,m,n,p,q,t,x,z,period,bad,pos,col,len,flag;
    
    if(document.getElementById('encipher').checked) 
      {
           encipher=1;
      }
  else if(document.getElementById('decipher').checked) 
      {
       encipher=0;;
      }
    
    key=document.getElementById('key').value;
    txt = document.getElementById('input_area').value;
   
   
	txt=txt.toUpperCase();
	key=key.toUpperCase();
    
    //...remove spaces and select only alphabet letters...
    buffer=""; 
    for(j=0;j<txt.length;j++)
      if( txt.charAt(j)>='A' && txt.charAt(j)<='Z')
        buffer+=txt.charAt(j);   
     len=buffer.length;
         
     pack="";
     for(j=0;j<key.length;j++)
       if( key.charAt(j)>='A' && key.charAt(j)<='Z')
         pack+=key.charAt(j); 
         
     if(pack.length<26)
       for(j=0;j<26;j++)
         {
          flag=0;
          for(k=0;k<pack.length;k++)
             if(permit.charAt(j)==pack.charAt(k)) {flag=1; break;}
          if(flag==0) pack=pack+permit.charAt(j);
         }   
     key=pack;      
      
         //....encipher.....
         if(encipher==1)  {pt=buffer; ct="";}
         else             {ct=buffer;pt="";}
        n=0;
        for(j=0;j<len;j++)
        
           {
             if(encipher==1) // ENCIPHER
                 {
                  //....find position of plain letter in pack....
                  for(pos=0;pos<26;pos++) if(pt.charAt(j)==pack.charAt(pos)) break;
                  //.... cipher letter is before plain in pack...... 
                  x=pos-1; if(x<0) x+=26;
                  ct+=pack.charAt(x);
                  n++; if(n==5){n=0; ct=ct+" ";}  
                  }
               else//DECIPHER
                  {
                   //....find position of cipher letter in pack....
                  for(pos=0;pos<26;pos++) if(ct.charAt(j)==pack.charAt(pos)) break;
             
                   //.... plain letter is after cipher in pack...... 
                   x=pos+1; x=x%26;
                   pt+=pack.charAt(x);
                  }   
         
             
            //...make transposition key, 10 cols...
             z=pt.charCodeAt(j)-65;  
             x=pos;
             if(encipher==0) x=pos+1;
             for(m=0;m<10;m++)
               {
                 x=(z+x)%26;
                 trans[m]=pack.charCodeAt(x)-65;
               } 
             
          //....pick up transposed pack...   
             buffer="";
            for(p=0;p<26;p++)
              {
               for(q=0;q<10;q++)
                   if(p==trans[q])
                     {
                      col=q; x=q;
                      while(x<26)
                        {
                          buffer+=pack.charAt(x);
                          x=x+10;
                        }
                     }
              }  
           pack=buffer;
           
         } 
   
       if(encipher==1) txt="Key = "+ key+"\n\n Ciphertext = "+ct;
       else            txt="Key = "+ key+"\n\n Plaintext = "+pt;
       
       document.getElementById('output_area').value = txt;