/*
 * Jubal's encrypting tool
 *
 * This program reads in a file and:
 *   decrypts the file if it ends in EXTENSION (#defined below)
 *   encrypts the file otherwise
 * The encryption is done by rotating with a key that the user selects
 * The first lines of the file are the header
 * Then, the next line is the key encrypted with crypt() (for checking keys)
 * After that is the data.
 *
 * This is a bin/ type command.  To invoke it, call the function main()
 *
 *                Enjoy,   Jubal  (Dave Ljung, DaveSource.com/GetDave.com)
 */

/*
 * This program has been successfully ported to the following drivers:
 * 2.4.5, 3.1.2, 3.1.2 -DR, 3.1.2 -CD and 3.2 (amylaar)
 *
 * This code is copyright 1993, David Ljung Madison (DaveSource.com/GetDave.com)
 *
 * It may be freely redistributed, but it may not be sold in any form.
 */

/* consideration:  make the write_file a diff. function
 * and then do a call_out to help take care of too long eval error (big files)
 * This won't work on most systems, because call_outs often can't do file I/O
 */

#define MAX_ARRAY 1000

/* last character of header MUST be '\n' */
/* Don't change the HEADER or else you won't be able to uncrypt files! */
#define HEADER "\
This file was created by Jubal's 'crypt' program\n\
Please do not alter it in ANY way as this will destroy the contents\n\
-------------------------------------------------------------------\n"

/* filename extension */
#define EXTENSION ".x"

/* don't touch this! :) */
#define CHARS ({"`","1","2","3","4","5","6","7","8","9","0","-","=","	", \
"q","w","e","r","t","y","u","i","o","p","[","]","\\","a","s","d","f","g","h", \
"j","k","l",";","'","z","x","c","v","b","n","m",",",".","/"," ","~","!","@", \
"#","$","%","^","&","*","(",")","_","+","Q","W","E","R","T","Y","U","I","O", \
"P","{","}","|","A","S","D","F","G","H","J","K","L",":","\"","Z","X","C","V", \
"B","N","M","<",">","?"})


/* global variables!  Don't let two players use this command at once! */
string name,newname;
int crypt,overwrite;
string tmpkey;

main(what) {
  int totlines,l;

  if(!what) return !notify_fail("Usage: crypt <file>\n");

  name=mk_path(what);

  l=file_size(name);
  if(l==-1) {
    if(file_size(name+EXTENSION)==-1)
      return write(name+" does not exist\n"), 1;
    name=name+EXTENSION;
    l=file_size(name);
  }
  if(l==-2) return write(name+" is a directory\n"), 1;
  if(l==0) return write(name+" is empty\n"), 1;

  l=strlen(name);
  if(name[l-strlen(EXTENSION)..l-1]==EXTENSION) {
    newname=name[0..l-strlen(EXTENSION)-1];
    crypt=0;
  } else {
    newname=name+EXTENSION;
    crypt=1;
  }
  overwrite=0;

  write((crypt?"En":"De")+"crypting: "
         +name+" ("+(l/1000)+"."+(l-(l/1000*1000))+"k) to "+newname+"\n");

  write("Key: ");
  if(!crypt) input_to("get_key2",1);
  else input_to("get_key1",1);
  return 1;
}

get_key1(key) {
  tmpkey=key;
  write("\nKey (again): ");
  input_to("get_key2",1);
}

get_key2(key) {
  int i,l;

  write("\n");
  if(crypt && key!=tmpkey) {
    write("You changed!\n");
    tmpkey=0;
    key=0;
    return 1;
  }
  tmpkey=0;
  if(file_crypt(key,!crypt,name,newname)) {
    if(!rm(name)) write("Couldn't remove file: "+name+"\n");
    else write("Done.\n");
  }

  key=0;
  return 1;
}


/* the encryption routine */
file_crypt(key,decrypt,name,newname) {
  int lines,len,i,j,s1,s2,c,k;
  string in,out,*chars,seed,hdr;

  chars=CHARS;
  s1=sizeof(chars);
  s2=strlen(key)-1;
  k=0;

  i=1;

  if(file_size(newname)!=-1)
    if(!overwrite) return write(newname+" already exists\n"), 0;
    else if(!rm(newname)) return write("Could not remove "+newname+"\n"), 0;

  if(!crypt) {
    hdr=explode(HEADER,"\n");
    
    while(i<=sizeof(hdr)) {
      if(read_file(name,i)!=hdr[i-1]+"\n")
        return write("Corrupt header\n"), 0;
      i++;
    }
    in=read_file(name,i);
    if(crypt(key,in)!=in[0..strlen(in)-2])
      return write("Wrong key\n"), 0;
    i++;
  } else {
    j=random(s1); if(chars[j]=="\n") j=5; seed=chars[j];
    j=random(s1); if(chars[j]=="\n") j=6; seed+=chars[j];
    if(!write_file(newname,HEADER+crypt(key,seed)+"\n"))
      return write("ERROR: writing header\n"), 0;
  }

  while(in=read_file(name,i)) {
    i++;
    len=strlen(in);
    out="";
    for(j=0;j<len;j++) {
      c=member_array(in[j..j],chars);
      if(c==-1) out+=in[j..j];
      else {
        c=decrypt?c-key[k]:c+key[k];
        while(c<0) c+=s1;
        while(c>=s1) c-=s1;
        k=k+1>s2?0:k+1;
        out+=chars[c];
      }
    }
    if(!write_file(newname,out))
      return write("ERROR: writing line: "+i+" to: "+newname+"\n"), 0;
  }
  return 1;
}

/* this can be altered in many ways -- use valid_write, mk_path, whatever */
/* make sure it returns the prepending "/" */
mk_path(name) {
  /* resolve_path and prepending '/' for use on Virtual Realities */
  return "/"+resolve_path(this_player()->query_path(),name);
  return this_player()->mk_path(name);
}