TweetFollow Us on Twitter

Password
Volume Number:7
Issue Number:7
Column Tag:C Workshop
Related Info: Dialog Manager

Password Dialogs

By Bill Schilit, New York, NY

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

Making a Password Dialog

Bill Schilit has been programming the Macintosh since the days of the 128K. He co-authored Macintosh Kermit, and the CAP Appletalk-Unix File Server. Bill is currently a graduate student at Columbia University’s Computer Science department.

This article describes how to program a dialog with a non-displaying “password” field. In this type of dialog, when the user types in his or her password all they see are bullet characters (“•”) -- because you never know who may be looking over your shoulder.

The password field of the dialog must handle delete, backspace, and replacement of the text selection. Basically, even though you can’t see the characters being entered you want it to act like a normal Text Edit field. One nice solution to the problem is to create an offscreen TE field to hold the plain text password while the dialog TE field holds the bullets.

The Login Dialog

In the program below, LoginDialog() is called to display the dialog box, it returns the user name and password entered by the user. The filter procedure, LoginFilter() does the real work here: it checks the name and password lengths, keeps the offscreen TE record up to date, and exchanges the password character with a bullet.

LoginDialog() first loads the dialog from the resource file and then calls SetPort() to set the GrafPort to the dialog window. SetPort is required for TENew() a few lines below, since TextEdit remembers the GrafPort for you. The destination and view rectangles we supply to TENew() are outside of the dialog window, so we never actually see this TE field. After creating the invisible text edit field, a pointer to it is stored in the dialog window via SetWRefCon() so that the filter procedure has access to it.

The rest of LoginDialog() is fairly standard. The procedure loops until the user types the OK button at which point the user name and password fields are copied for the caller. Within the dialog loop the OK button is enabled or disabled -- if the password and username have some type in then OK is enabled, otherwise it is disabled.

Figure 1. Password Dialog Box

The Login Filter

LoginFilter() is the standard filter procedure called by our modal dialog. If you remember your Inside Mac then you know that returning TRUE from the filter proc means we have handled the event, and the item number is in itemHit. Returning FALSE lets ModalDialog process the event. Our filter proc is only concerned with keyboard events, so the first line in procedure LoginFilter causes a return on all other types of events.

The next task in LoginFilter() is to handle the characters tab and return (tab moves to the next field and return is the same as the default button). The filter returns here if either of these characters was typed.

The filter procedure now does the work of checking field lengths and setting those bullets. The dialog’s text edit handle and the editField tell us which field is getting type in and how large the current edit record is. We first check that adding the character will not push us past the password or user name size limit, if so the filter gives a beep and ignores the character. Notice that the auxiliary routine we call to check the length of the text edit field given the new character is smart about checking for deletes, backspace, and selection replacements.

When the character is destined for the password item we do our final manipulations. The handle to our invisible text edit record is fetched from the dialog refCon, and the selection (and insertion point) are set to be exactly the same as in the password field. TEKey() is called to insert the character into our invisible text edit. Now, unless the character is a delete or backspace, the character in the event record is replaced by a bullet. We return to ModalDialog telling it to handle the event with the now obscured character for the password field. When the dialog is complete, the password is available from the invisible text edit field.

LOGIN DIALOG.C

/*
 * Login Dialog.c - Dialog for User Login.
 *
 * Copyright (c) 1988 by Bill Schilit.
 *
 * Edit History:
 *
 *  April 23, 1988      Schilit    Created
 *  May 9, 1988         Schilit    Clean up
 *
 */

/* Includes MacHeaders */

#include “Login Dialog.h”

/* Prototypes */

static int 
TELengthCheck(TEPtr te,char c,int maxLen);

static void
TECpyText(TEHandle teH,Ptr p);

pascal Byte 
LoginFilter(DialogPtr dPtr,
        EventRecord *ePtr,short *iHit);

/*
 * LDialogStg contains the global vars used 
 * by the filter proc and user item procs in
 * our login dialog. A pointer to the 
 * LDialogStg is stored in the window refcon
 * of the dialog window.
 */

typedef struct {
    TEHandle passTeH;
} LDialogStg, *LDialogStgPtr;

/*
 * static Byte 
 *  LoginFilter(DialogPtr theDialog,
 *              EventRecord *theEvent,
 *              int *itemHit);
 *
 * Modal dialog filter to echo bullet 
 * (‘\245’) instead of the user’s password
 * and to limit the number of characters in
 * both the user name and password edit
 * records.
 */

static pascal Byte
LoginFilter(theDialog,theEvent,itemHit)
DialogPtr theDialog;
EventRecord *theEvent;
short *itemHit;
{
    register char c;
    int field,tooBig;
    TEPtr tePtr;
    LDialogStg *ldStg;
    
    /* we’re only interested in keyboard 
     * events. If not a key, let modal 
     * process as usual
     */
     
    if (theEvent->what != keyDown && 
        theEvent->what != autoKey)
            return(false);
    
    /* fetch the character from the
     * event message 
     */    

    c = theEvent->message & charCodeMask;
    
    /* Check for CR and convert to OK button.
     * Check for TAB and let it pass.
     */
     
    if (c == CR) {
        *itemHit = OK;
        return(true);
    }
    
    if (c == ‘\t’)
        return(false);

    /* make sure the edit text item is one
     * we are interested in and check to see
     * if the length is not too large.
     */
     
    field = 
      ((DialogPeek) theDialog)->editField+1;
    
    tePtr = 
      *(((DialogPeek) theDialog)->textH);

    /* User is typing in the nameItem -- 
     * our only interest is the size 
     */
    
    if (field == nameItem) {
        tooBig = 
          TELengthCheck(tePtr,c,MAXNAME);

     /* give a beep if too big, and return
      * TRUE to ignore the event.
      */
      
        if (tooBig)
            SysBeep(1);   
        return(tooBig);   
    }
    
    /* If typing into the password, check the
     * size, then diddle the character so 
     * bullet (\245) shows up instead of what
     * the user typed.
     */
     
    if (field == passwdItem) {
        if (TELengthCheck(tePtr,c,MAXPWD)) {
            SysBeep(1);
            return(true);
        }
        
   /* Insert the char into our private
     * password text edit record. First
     * set the text selection so action
     * mimicks exactly what user is 
     * selecting and typing in passwdItem
     * text edit field.
     */
    
        ldStg = (LDialogStg *) 
          GetWRefCon(theDialog);
          
        if (ldStg == 0)
            return(false);
            
        TESetSelect(tePtr->selStart,
                    tePtr->selEnd,
                    ldStg->passTeH);
                    
        TEKey(c,ldStg->passTeH);
    
        /* unless BS or DEL, replace the
         * password character with bullet 
         */

        if (c != DEL && c != BS)
            theEvent->message = ‘\245’ | 
            (theEvent->message & 
              ~charCodeMask);
        return(false);       /* return ok */
    }
    
    return(false);           /* all other items */
    
}    

/*
 * static int 
 * TELengthCheck(tePtr te,char c,int maxLen)
 *
 * Check that adding character c to the text
 * edit te does not cause more than maxLen
 * chars in the text edit item:
 *
 * 1) If delete or backspace then length will
 *    decrease so ok.
 * 2) If a selection range of 1 or more chars 
 *    then same as above.
 * 3) Finally just check the length of the 
 *    edit item. 
 *
 *
 * Returns: FALSE if OK, TRUE if too large.
 *
 */
 
static int
TELengthCheck(te,c,maxLen)
TEPtr te;
char c;
int maxLen;
{

   /* this char a del or bs */
   /*  if so, does not increase */
 
    if (c == DEL || c == BS)
        return(false);       

    /* selected a region? */
    /* if so, then does not increase */
    
    if (te->selStart < 
        te->selEnd)           
        return(false);      
   
   /* else will insert, check length */
      
    if (te->teLength < maxLen) 
        return(false);
    
    return(true);
}

/*
 * static void TECpyText(TEHandle teH,Ptr p)
 *
 * Fetch the text from the text edit handle
 * and store as a pascal string in Ptr p.
 *
 * NB: This only works if the TE text is less
 * than 255 characters (a pascal string 
 * limit) so be careful.
 *
 */
 
static void
TECpyText(teH,p)
TEHandle teH;
Ptr p;
{
    p[0] = (unsigned char) (*teH)->teLength;
    BlockMove(*(*teH)->hText,&p[1],p[0]);
}

/*
 * LoginDialog(char *uName,*uPassword)
 *
 * Perform a login dialog and return the user
 * name and password in uName and uPassword.
 *
 * The dialog has a special filter procedure
 * which echos bullet characters in the
 * password field.
 * 
 * The length of the username and password
 *  are limited to MAXNAME and MAXPWD.
 * 
 * Note: we do not issue ParamText() since 
 * this affects other dialogs on the screen.
 * 
 */
 
LoginDialog(uName,uPasswd)
char *uName,*uPasswd;
{
    DialogPtr d;
    short itemHit;
    Rect aRect;
    int theKind;
    Handle nameHdl,okHdl;
    Boolean okOK = false;
    LDialogStg LDStg;
    

    d = GetNewDialog(LOGIN_DLOG,
                     (Ptr) 0,(Ptr) -1);
                     
    if (d == 0)
        return;
  
    /* make it the current port */          
  
    SetPort(d);         
    
    /* Make an offscreen rect for the text
     * edit to hold the plain text of the
     * entered password.
     * 
     * The dialog edit text for the password
     * will get “•” for each character typed.
     */
     
    SetRect(&aRect,0,0,1,1);
    OffsetRect(&aRect,
                d->portRect.right,
                d->portRect.bottom);
    
    LDStg.passTeH = TENew(&aRect,&aRect);
    
    /* Set the window data to be a pointer
     * to storage needed by filter procedure.
     */
     
    SetWRefCon(d,(long) &LDStg);
  /* Get handles for Name field and 
     * OK Button 
     */
        
    GetDItem(d,nameItem,&theKind,
             &nameHdl,&aRect);
    GetDItem(d,okItem,&theKind,
             &okHdl,&aRect);
    
    ShowWindow(d);
    
    while (!(okOK && itemHit == okItem)) {
        
        /* Set okOK to true if password and
         * name fields both have more than
         * one character. Enable/Disable the
         * OK button accordingly.
         */
         
        GetIText(nameHdl,uName);
        okOK = 
          (*LDStg.passTeH)->teLength > 0 &&
           uName[0] > 0;
                
        HiliteControl((ControlHandle) okHdl,
                      okOK ? 0 : 255);
        
        ModalDialog(LoginFilter,&itemHit);
    }
    
    /* Store the password and username
     *  for the caller then clean up.
     */
    
    TECpyText(LDStg.passTeH,uPasswd);
    GetIText(nameHdl,uName);

    DisposDialog(d);    
    TEDispose(LDStg.passTeH);
}

LOGIN MAIN.C

/*
 * Login Main.c - Main for Login Example.
 * This program built under LSC 3.0
 * Copyright (c) 1988 by Bill Schilit.
 * Edit History:
 *  April 23, 1988     Schilit    Created
 *  May 9, 1988        Schilit    Clean up
 */

/* MacHeaders included */

#include “Login Dialog.h”

#define ALERTID 128

main()
{    
    char User[255];
    char Password[255];
    
    InitGraf(&thePort);
    InitFonts();
    InitWindows();
    InitMenus();
    TEInit();
    InitDialogs(0);
    FlushEvents(everyEvent,0);
    InitCursor();
            
    /* Show the login dialog box and
     * repeat until the user types
     * the matching password.
     */
     
    for (;;) {
    
        /* Call LoginDialog to get user name 
         * and password.
         */
        
        LoginDialog(User,Password);
        
        /* Compare the entered password with
         * “swordfish” -- case doesn’t matter
         *  -- and exit if a match.
         */
         
        if (EqualString(Password,
                        “\pSwordFish”,
                        false,false))
            ExitToShell();
            
        /* No match, show our alert box with
         * a hint, and repeat the process.
         */
         
        ParamText(User,0,0,0);
        Alert(ALERTID,(ProcPtr) 0);
    }
}
LOGIN DIALOG.H

/*
 * Login Dialog.h - Definitions for 
 *                   Login Dialog.
 * This program built under LSC 3.0
 * Copyright (c) 1988 by Bill Schilit.
 * Edit History:
 *    April 23, 1988     Schilit   Created
 *    May 9, 1988        Schilit   Clean up
 */


#define LOGIN_DLOG 256

enum {           /* DITL for LOGIN_DLOG */
    okItem=1,    /* OK button */
    nameItem,    /* edit text name */
    passwdItem,  /* edit text password */
    myIconItem   /* the icon */
};

enum {           /* ASCII definitions */
    CR = 0x0d,
    DEL = 0x7f,
    BS = 0x08
};


  /* max chars in a password */
  
#define MAXPWD 10    

  /* max chars in a user name */
  
#define MAXNAME 12   

/* PROTOTYPES */

LoginDialog(char *uName,char *uPasswd);

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Duplicate Annihilator 5.7.5 - Find and d...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator... Read more
BusyContacts 1.0.2 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
Capture One Pro 8.2.0.82 - RAW workflow...
Capture One Pro 8 is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 300 high-end cameras -- straight out of the box. It... Read more
Backblaze 4.0.0.872 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac.With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Little Snitch 3.5.2 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more
Monolingual 1.6.4 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. If you use your computer in only one (human) language, you... Read more
CleanApp 5.0 - Application deinstaller a...
CleanApp is an application deinstaller and archiver.... Your hard drive gets fuller day by day, but do you know why? CleanApp 5 provides you with insights how to reclaim disk space. There are... Read more
Fantastical 2.0 - Create calendar events...
Fantastical is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event details... Read more
Cocktail 8.2 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Direct Mail 4.0.4 - Create and send grea...
Direct Mail is an easy-to-use, fully-featured email marketing app purpose-built for OS X. It lets you create and send great looking email campaigns. Start your newsletter by selecting from a gallery... Read more

Fast & Furious: Legacy's Creati...
| Read more »
N-Fusion and 505's Ember is Totally...
| Read more »
These are All the Apple Watch Apps and G...
The Apple Watch is less than a month from hitting store shelves, and once you get your hands on it you're probably going to want some apps and games to install. Fear not! We've compiled a list of all the Apple Watch apps and games we've been able to... | Read more »
Appy to Have Known You - Lee Hamlet Look...
Being at 148Apps these past 2 years has been an awesome experience that has taught me a great deal, and working with such a great team has been a privilege. Thank you to Rob Rich, and to both Rob LeFebvre and Jeff Scott before him, for helping me... | Read more »
Hands-On With Allstar Heroes - A Promisi...
Let’s get this out of the way quickly. Allstar Heroes looks a lot like a certain other recent action RPG release, but it turns out that while it’s not yet available here, Allstar Heroes has been around for much longer than that other title. Now that... | Read more »
Macho Man and Steve Austin Join the Rank...
WWE Immortals, by Warner Bros. Interactive Entertainment and WWE, has gotten a superstar update. You'll now have access to Macho Man Randy Savage and Steve Austin. Both characters have two different versions: Macho Man Randy Savage Renegade or Macho... | Read more »
Fearless Fantasy is Fantastic for the iF...
I actually had my first look at Fearless Fantasy last year at E3, but it was on a PC so there wasn't much for me to talk about. But now that I've been able to play with a pre-release version of the iOS build, there's quite a bit for me to talk... | Read more »
MLB Manager 2015 (Games)
MLB Manager 2015 5.0.14 Device: iOS Universal Category: Games Price: $4.99, Version: 5.0.14 (iTunes) Description: Guide your favorite MLB franchise to glory! MLB Manager 2015, officially licensed by MLB.com and based on the award-... | Read more »
Breath of Light (Games)
Breath of Light 1.0.1421 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.1421 (iTunes) Description: Hold a quiet moment. Breath of Light is a meditative and beautiful puzzle game with a hypnotic soundtrack by... | Read more »
WWE WrestleMania Tags into the App Store
Are You ready to rumble? The official WWE WrestleMania app, by World Wrestling Entertainment, is now available. Now you can get all your WrestleMania info in one place before anyone else. The app offers details on superstar signings, interactive... | Read more »

Price Scanner via MacPrices.net

13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.... Read more
Save up to $80 on iPad Air 2s, NY tax only, f...
 B&H Photo has iPad Air 2s on sale for $80 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $469.99 $30 off - 64GB iPad Air 2 WiFi: $549.99 $50 off - 128GB iPad... Read more
iMacs on sale for up to $205 off MSRP
B&H Photo has 21″ and 27″ iMacs on sale for up to $205 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $1019 $80 off - 21″ 2.7GHz iMac: $1189 $110 off - 21″ 2.9GHz... Read more
Färbe Technik Offers iPhone Battery Charge LI...
Färbe Technik, which manufactures and markets of mobile accessories for Apple, Blackberry and Samsung mobile devices, is offering tips on how to keep your iPhone charged while in the field: •... Read more
Electronic Recyclers International CEO Urges...
Citing a recent story on CNBC about concerns some security professionals have about the forthcoming Apple Watch, John Shegerian, Chairman and CEO of Electronic Recyclers International (ERI), the... Read more
Save up to $380 with Apple refurbished iMacs
The Apple Store has Apple Certified Refurbished iMacs available for up to $380 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $2119 $... Read more
Mac minis on sale for up to $75 off, starting...
MacMall has Mac minis on sale for up to $75 off MSRP including free shipping. Their prices are the lowest available for these models from any reseller: - 1.4GHz Mac mini: $459.99 $40 off - 2.6GHz Mac... Read more
College Student Deals: Additional $50 off Mac...
Take an additional $50 off all MacBooks and iMacs at Best Buy Online with their College Students Deals Savings, valid through April 11, 2015. Anyone with a valid .EDU email address can take advantage... Read more
Mac Pros on sale for up to $260 off MSRP
B&H Photo has Mac Pros on sale for up to $260 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2799, $200 off MSRP - 3.5GHz 6-core Mac Pro: $3719.99... Read more
13-inch 2.5GHz MacBook Pro on sale for $100 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more

Jobs Board

DevOps Software Engineer - *Apple* Pay, iOS...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Lead *Apple* Solutions Consultant - Retail...
**Job Summary** Job Summary The Lead ASC is an Apple employee who serves as the Apple business manager and influencer in a hyper-business critical Reseller's store Read more
*Apple* Pay - Site Reliability Engineer - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.