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);

 
AAPL
$116.47
Apple Inc.
+0.16
MSFT
$47.98
Microsoft Corpora
-0.72
GOOG
$537.50
Google Inc.
+2.67

MacTech Search:
Community Search:

Software Updates via MacUpdate

Cobook 3.0.7 - Intelligent address book....
Cobook Contacts is an intuitive, engaging address book. Solve the problem of contact management with Cobook Contacts and its simple interface and powerful syncing and integration possibilities.... Read more
StatsBar 1.9 - Monitor system processes...
StatsBar gives you a comprehensive and detailed analysis of the following areas of your Mac: CPU usage Memory usage Disk usage Network and bandwidth usage Battery power and health (MacBooks only)... Read more
Cyberduck 4.6 - FTP and SFTP browser. (F...
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Evernote 6.0.1 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
calibre 2.11 - Complete e-library manage...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital... Read more
Herald 5.0.1 - Notification plugin for M...
Note: Versions 2.1.3 (for OS X 10.7), 3.0.6 (for OS X 10.8), and 4.0.8 (for OS X 10.9) are no longer supported by the developer. Herald is a notification plugin for Mail.app, Apple's Mac OS X email... Read more
Firetask 3.7 - Innovative task managemen...
Firetask uniquely combines the advantages of classical priority-and-due-date-based task management with GTD. Stay focused and on top of your commitments - Firetask's "Today" view shows all relevant... Read more
TechTool Pro 7.0.6 - Hard drive and syst...
TechTool Pro is now 7, and this is the most advanced version of the acclaimed Macintosh troubleshooting utility created in its 20-year history. Micromat has redeveloped TechTool Pro 7 to be fully 64... Read more
PhotoDesk 3.0.1 - Instagram client for p...
PhotoDesk lets you view, like, comment, and download Instagram pictures/videos! (NO Uploads! / Image Posting! Instagram forbids that! AND you *need* an *existing* Instagram account). But you can do... Read more

Latest Forum Discussions

See All

Ubisoft Gives Everyone Two New Ways to E...
Ubisoft Gives Everyone Two New Ways to Earn In-Game Stuff for Far Cry 4 Posted by Jessica Fisher on November 21st, 2014 [ permalink ] | Read more »
Golfinity – Tips, Tricks, Strategies, an...
Dig this: Would you like to know what we thought of being an infinite golfer? Check out our Golfinity review! Golfinity offers unlimited ways to test your skills at golf. Here are a few ways to make sure your score doesn’t get too high and your... | Read more »
Dark Hearts, The Sequel to Haunting Meli...
Dark Hearts, The Sequel to Haunting Melissa, is Available Now Posted by Jessica Fisher on November 21st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Meowza! Toyze Brings Talking Tom to Life...
Meowza! | Read more »
Square Enix Announces New Tactical RPG f...
Square Enix Announces New Tactical RPG for Mobile, Heavenstrike Rivals. Posted by Jessica Fisher on November 21st, 2014 [ permalink ] With their epic stories and gorgeous graphics, | Read more »
Quest for Revenge (Games)
Quest for Revenge 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: The great Kingdom of the west has fallen. The gods ignore the prayers of the desperate. A dark warlord has extinguished... | Read more »
Threadz is a New Writing Adventure for Y...
Threadz is a New Writing Adventure for You and Your Friends Posted by Jessica Fisher on November 21st, 2014 [ permalink ] In the tradition of round-robin storytelling, | Read more »
SteelSeries Stratus XL Hardware Review
Made by: SteelSeries Price: $59.99 Hardware/iOS Integration Rating: 4 out of 5 stars Usability Rating: 4.5 out of 5 stars Reuse Value Rating: 4.25 out of 5 stars Build Quality Rating: 4.5 out of 5 stars Overall Rating: 4.31 out of 5 stars | Read more »
ACDSee (Photography)
ACDSee 1.0.0 Device: iOS iPhone Category: Photography Price: $1.99, Version: 1.0.0 (iTunes) Description: Capture, perfect, and share your photos with ACDSee. The ACDSee iPhone app combines an innovative camera, a powerful photo... | Read more »
ProTube for YouTube (Entertainment)
ProTube for YouTube 2.0.2 Device: iOS Universal Category: Entertainment Price: $1.99, Version: 2.0.2 (iTunes) Description: ProTube is the ultimate, fully featured YouTube app. With it's highly polished design, ProTube offers ad-free... | Read more »

Price Scanner via MacPrices.net

Save up to $400 with Apple refurbished 2014 1...
The Apple Store has restocked Apple Certified Refurbished 2014 15″ Retina MacBook Pros for up to $400 off the cost of new models. An Apple one-year warranty is included with each model, and shipping... Read more
New 13-inch 1.4GHz MacBook Air on sale for $8...
 Adorama has the 2014 13″ 1.4GHz/128GB MacBook Air on sale for $899.99 including free shipping plus NY & NJ tax only. Their price is $100 off MSRP. B&H Photo has the 13″ 1.4GHz/128GB MacBook... Read more
Apple Expected to Reverse Nine-Month Tablet S...
Apple and Samsung combined accounted for 62 percent of the nearly 36 million branded tablets shipped in 3Q 2014, according to early vendor shipment share estimates from market intelligence firm ABI... Read more
Stratos: 30 Percent of US Smartphone Owners t...
Stratos, Inc., creator of the Bluetooth Connected Card Platform, has announced results from its 2014 Holiday Mobile Payments Survey. The consumer survey found that nearly one out of three (30 percent... Read more
2014 1.4GHz Mac mini on sale for $449, save $...
 B&H Photo has lowered their price on the new 1.4GHz Mac mini to $449.99 including free shipping plus NY tax only. Their price is $50 off MSRP, and it’s the lowest price available for this new... Read more
Check Apple prices on any device with the iTr...
MacPrices is proud to offer readers a free iOS app (iPhones, iPads, & iPod touch) and Android app (Google Play and Amazon App Store) called iTracx, which allows you to glance at today’s lowest... Read more
64GB iPod touch on sale for $249, save $50
Best Buy has the 64GB iPod touch on sale for $249 on their online store for a limited time. Their price is $50 off MSRP. Choose free shipping or free local store pickup (if available). Sale price for... Read more
15″ 2.2GHz Retina MacBook Pro on sale for $17...
 B&H Photo has the 2014 15″ 2.2GHz Retina MacBook Pro on sale for $1799.99 for a limited time. Shipping is free, and B&H charges NY sales tax only. B&H will also include free copies of... Read more
New Logitech AnyAngle Case/Stand Brings Flexi...
Logitec has announced the newest addition to its suite of tablet products — the Logitech AnyAngle. A protective case with an any-angle stand for iPad Air 2 and all iPad mini models, AnyAngle is the... Read more
Notebook PC Shipments Rise Year-Over-Year as...
According to preliminary results from the upcoming DisplaySearch Quarterly Mobile PC Shipment and Forecast Report, the global notebook PC market grew 10 percent year-over-year in Q3’14 to 49.4... Read more

Jobs Board

*Apple* Solutions Consultant (ASC)- Retail S...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and Read more
*Apple* Store Leader Program - College Gradu...
Job Description: Job Summary As an Apple Store Leader Program agent, you can continue your education as you major in the art of leadership at the Apple Store. You'll 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
Senior Event Manager, *Apple* Retail Market...
…This senior level position is responsible for leading and imagining the Apple Retail Team's global event strategy. Delivering an overarching brand story; in-store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.