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Annotation of pgp/src/noise.c, revision 1.1.1.4

1.1.1.4 ! root        1: /*
        !             2:  * Get environmental noise.
        !             3:  *
        !             4:  * (c) Copyright 1990-1996 by Philip Zimmermann.  All rights reserved.
        !             5:  * The author assumes no liability for damages resulting from the use
        !             6:  * of this software, even if the damage results from defects in this
        !             7:  * software.  No warranty is expressed or implied.
        !             8:  *
        !             9:  * Note that while most PGP source modules bear Philip Zimmermann's
        !            10:  * copyright notice, many of them have been revised or entirely written
        !            11:  * by contributors who frequently failed to put their names in their
        !            12:  * code.  Code that has been incorporated into PGP from other authors
        !            13:  * was either originally published in the public domain or is used with
        !            14:  * permission from the various authors.
        !            15:  *
        !            16:  * PGP is available for free to the public under certain restrictions.
        !            17:  * See the PGP User's Guide (included in the release package) for
        !            18:  * important information about licensing, patent restrictions on
        !            19:  * certain algorithms, trademarks, copyrights, and export controls.
        !            20:  *
        !            21:  * Written by Colin Plumb.
        !            22:  */
        !            23: 
        !            24: 
        !            25: #ifdef UNIX
        !            26: #include <sys/types.h>
        !            27: #include <sys/time.h>          /* For gettimeofday() */
        !            28: #include <sys/times.h>         /* for times() */
        !            29: #include <stdlib.h>            /* For qsort() */
        !            30: #endif /* UNIX */
        !            31: 
        !            32: #include <time.h>
        !            33: #include "usuals.h"
        !            34: #include "randpool.h"
        !            35: #include "noise.h"
        !            36: #ifdef MACTC5
        !            37: #include "TimeManager.h"
        !            38: #endif
        !            39: 
        !            40: #ifdef AMIGA  /* RKNOP 940613 */
        !            41: #include <devices/timer.h>
        !            42: #include <hardware/custom.h>
        !            43: #include <exec/execbase.h>
        !            44: extern __far struct Custom custom;   /* Custom chips */
        !            45: #include <proto/exec.h>
        !            46: #include <proto/timer.h>
        !            47: 
        !            48: /* Stuff used in noise.c, defined in random.c -- RKNOP 940613*/
        !            49: extern struct timerequest *TimerIO;
        !            50: extern union { struct timeval t;
        !            51:                struct EClockVal e;
        !            52:              } time0,time1;
        !            53: extern unsigned short use_eclock;
        !            54: #endif  /* AMIGA */
        !            55: 
        !            56: /* Some machines just don't have clock_t */
        !            57: #if defined(sun) && defined(i386)
        !            58: typedef long clock_t;
        !            59: #endif
        !            60: 
        !            61: #if defined(MSDOS) || defined(__MSDOS__)
        !            62: 
        !            63: /* Use IBM PC hardware timer (1.19 MHz) */
        !            64: 
        !            65: #ifdef __GO32__
        !            66: #include <pc.h>
        !            67: #else
        !            68: #include <conio.h>             /* for inp() and outp() */
        !            69: #include <dos.h>                /* same for Turbo C EWS */
        !            70: #endif
        !            71: 
        !            72: /* timer0 on 8253-5 on IBM PC or AT tics every .84 usec. */
        !            73: #define timer0         0x40    /* 8253 timer 0 port */
        !            74: #define timercntl      0x43    /* 8253 control register */
        !            75: 
        !            76: /*
        !            77:  * On an IBM PC, timer 0 ticks every .84 usec.  It counts down
        !            78:  * from 65536 by twos, toggling its output line after each
        !            79:  * step.  On an original IBM PC, we can thus only get 15 bits
        !            80:  * of the timer.  On a PC-AT or later, with an 8284 timer chip,
        !            81:  * we can get all 16 bits by reading the status, which has the
        !            82:  * state of the output bit in bit 7, and is effectively the
        !            83:  * high bit of the counter.
        !            84:  *
        !            85:  * But latching the status is a command which the 8283 does not
        !            86:  * recognize; the subsequent load is interpreted as one of
        !            87:  * a pair to read the counter instead of the status.  (We get a
        !            88:  * garbage bit instead of the one we expected, but that's no worse
        !            89:  * than constant 0.)  But the 8283 doesn't like single reads.
        !            90:  * (The 8284 is more forgiving.)
        !            91:  *
        !            92:  * So, to resolve all this, the following sequence is used:
        !            93:  *
        !            94:  * - Dummy read from counter 0 (low byte)
        !            95:  * - Latch status and count (ignored by 8283)
        !            96:  * - Read status (high byte on 8283)
        !            97:  * - Latch count (ignored by 8284, as count is already latched)
        !            98:  * - Read count (low)
        !            99:  * - Read count (high)
        !           100:  *
        !           101:  * It would be better (a project for the future) to capture the counter
        !           102:  * in a keyboard ISR, put it in a global variable, and have noise() read
        !           103:  * the global.  This gets the most accurate possible time, and avoids
        !           104:  * possible harmonic relationships with a keyboard polling loop.
        !           105:  * (Which MS-DOS, silly thing that it is, almost certainly uses
        !           106:  * internally.)
        !           107:  */
        !           108: static unsigned pctimer0(void)
        !           109: {
        !           110:     unsigned count;
        !           111: 
        !           112: #ifdef __GO32__
        !           113:     inportb(timer0);
        !           114:     outportb(timercntl, 0xC2);        /* Latch status and count for timer 0 */
        !           115:     count = (inportb(timer0) & 0x80) << 8;
        !           116:     outportb(timercntl, 0x00);        /* Latch count of timer 0 */
        !           117:     count |= (inportb(timer0) & 0xFF) >> 1;
        !           118:     count |= (inportb(timer0) & 0xFF) << 7;
        !           119: #else
        !           120:     inp(timer0);
        !           121:     outp(timercntl, 0xC2);     /* Latch status and count for timer 0 */
        !           122:     count = (inp(timer0) & 0x80) << 8;
        !           123:     outp(timercntl, 0x00);     /* Latch count of timer 0 */
        !           124:     count |= (inp(timer0) & 0xFF) >> 1;
        !           125:     count |= (inp(timer0) & 0xFF) << 7;
        !           126: #endif
        !           127: 
        !           128:     return count;
        !           129: }
        !           130: 
        !           131: #endif                         /* MSDOS || __MSDOS__ */
        !           132: 
        !           133: 
        !           134: #ifdef UNIX
        !           135: 
        !           136: #define NOISEDEBUG
        !           137: #ifdef NOISEDEBUG
        !           138: #include "pgp.h"               /* for verbose and pgpout */
        !           139: #include <stdio.h>
        !           140: #endif
        !           141: 
        !           142: /* Function needed for qsort() */
        !           143: static int noiseCompare(void const *p1, void const *p2)
        !           144: {
        !           145:     return *(int const *) p1 - *(int const *) p2;
        !           146: }
        !           147: 
        !           148: 
        !           149: #define DELTAS 15              /* Number of deltas to try */
        !           150: 
        !           151: /*
        !           152:  * Find the resolution of the gettimeofday() clock by sampling
        !           153:  * successive values until a tick boundary, at which point
        !           154:  * the delta is entered into a table.  The median of the table is
        !           155:  * returned as the system tick size.
        !           156:  *
        !           157:  * Some trickery is needed to defeat the habit systems have of
        !           158:  * always incrementing the microseconds field so that no two calls
        !           159:  * return the same value.  Thus, a "tick boundary" is assumed
        !           160:  * when successive calls return a difference of >2 us.
        !           161:  * (This catches cases where we make successive calls and one
        !           162:  * other task sneaks in between.  More tasks in between are
        !           163:  * sufficiently unlikely that they'll get cut off by the median
        !           164:  * filter.
        !           165:  *
        !           166:  * When a tick boundary is found, the *first* time read during
        !           167:  * the previous tick (tv_base) is subtracted from the new time
        !           168:  * to get the microseconds per tick.
        !           169:  *
        !           170:  * The median of the ticks is taken to eliminate outliers due to
        !           171:  * descheduling (extra large) or tv_base not being the "zero" time
        !           172:  * in a given tick (slightly small).
        !           173:  *
        !           174:  * Note that Suns have a 1 us timer, and in SunOS 4.1, they return
        !           175:  * that timer, but there is ~50 us of system-call overhead to get
        !           176:  * it, so this overestimates the tick size consdierably.  On
        !           177:  * SunOS 5.x/Solaris, the overhead has been cut to about 2.5 us,
        !           178:  * so the inter-call time alternates between 2 and 3 us.  Some
        !           179:  * better algorithms are required to cope with potentially faster
        !           180:  * machines that really do return 1 us granularity.
        !           181:  *
        !           182:  * Current best idea (unimplemented): Sample a large number, and
        !           183:  * track small (< 100 us) deltas in an array of counters, and
        !           184:  * large ones in an array of deltas.  There should be three
        !           185:  * bumps: 1 us auto-increment, the tick size (which may blend into
        !           186:  * the previous bump), and time-slicing.  We want to throw out
        !           187:  * the latter, then compute the average delta as the average cost
        !           188:  * of making a call, then throw out the small values if they
        !           189:  * are suspisciously smaller than this value.  Then some average
        !           190:  * of the remainder should provide a good value for the cost of
        !           191:  * making a call.
        !           192:  *
        !           193:  * The alternative to all this is to actually model the keystroke
        !           194:  * latencies and compute the entropy directly.  A model considering
        !           195:  * the previous interval only should be adequate.
        !           196:  */
        !           197: static unsigned noiseTickSize(void)
        !           198: {
        !           199:     int i;
        !           200:     int j;
        !           201:     unsigned deltas[DELTAS];
        !           202:     unsigned t;
        !           203:     struct timeval tv_base, tv_old, tv_new;
        !           204: 
        !           205:     i = j = 0;
        !           206:     gettimeofday(&tv_base, 0);
        !           207:     tv_old = tv_base;
        !           208:     do {
        !           209:        gettimeofday(&tv_new, 0);
        !           210:        if (tv_new.tv_usec > tv_old.tv_usec + 2) {
        !           211:            deltas[i++] = tv_new.tv_usec - tv_base.tv_usec +
        !           212:                1000000 * (tv_new.tv_sec - tv_base.tv_sec);
        !           213:            tv_base = tv_new;
        !           214:            j = 0;
        !           215:        }
        !           216:        tv_old = tv_new;
        !           217: 
        !           218:        /*
        !           219:         * If we are forever getting <= 2 us, then just assume
        !           220:         * it's 2 us.
        !           221:         */
        !           222:        if (j++ > 10000)
        !           223:            return 2;
        !           224:     } while (i < DELTAS);
        !           225: 
        !           226:     qsort(deltas, DELTAS, sizeof(deltas[0]), noiseCompare);
        !           227: 
        !           228:     t = deltas[DELTAS / 2];    /* Median */
        !           229: 
        !           230: #ifdef NOISEDEBUG
        !           231:     if (verbose)
        !           232:        fprintf(pgpout, "t = %u, clock frequency is %u Hz\n",
        !           233:                t, (2000000 + t) / (2 * t));
        !           234: #endif
        !           235: 
        !           236:     return t;
        !           237: }
        !           238: 
        !           239: #endif                         /* UNIX */
        !           240: 
        !           241: 
        !           242: /* (Written by Guy Geens 95/12/07)
        !           243: This routine gets the 200Hz counter from the system area.
        !           244: This part of memory is only accessible in supervisor mode.
        !           245: To add to randomness, also store 50/60/70Hz VBL (Vertical BLank)
        !           246: counter. (There are two flavours of this one: One counter is
        !           247: stopped while floppy disk access takes place, the other one keeps
        !           248: running. Which one to use? Both? No: the elapsed time would be
        !           249: connected (does this harm randomness? I don't know) and, when
        !           250: using a hard disk drive, the same!
        !           251: (I've just picked one.)
        !           252: */
        !           253: 
        !           254: #ifdef ATARI
        !           255: #ifdef __PUREC__
        !           256: #include <tos.h>
        !           257: #else
        !           258: #include <osbind.h>
        !           259: #endif
        !           260: static word32 counter,vblcount;
        !           261: 
        !           262: long getcount(void) {
        !           263:        counter= *((long*)0x4baL); /* _hz_200 */
        !           264:        vblcount= *((long*)0x466L); /* _frlock */
        !           265:        return counter;
        !           266: }
        !           267: 
        !           268: #endif
        !           269: 
        !           270: 
        !           271: /*
        !           272:  * Add as much environmentally-derived random noise as possible
        !           273:  * to the randPool.  Typically, this involves reading the most
        !           274:  * accurate system clocks available.
        !           275:  *
        !           276:  * Returns the number of ticks that has passed since the last call,
        !           277:  * for entropy estimation purposes.
        !           278:  */
        !           279: word32
        !           280: noise(void)
        !           281: {
        !           282:     static word32 lastcounter;
        !           283:     word32 delta;
        !           284:     time_t tnow;
        !           285:     clock_t cnow;
        !           286: 
        !           287:     cnow = clock();
        !           288:     randPoolAddBytes((byte *) & cnow, sizeof(cnow));
        !           289: 
        !           290:     tnow = time((time_t *) 0);
        !           291:     randPoolAddBytes((byte *) & tnow, sizeof(tnow));
        !           292: 
        !           293: #if defined(MSDOS) || defined(__MSDOS__)
        !           294:     {
        !           295:        unsigned t;
        !           296: 
        !           297:        t = pctimer0();
        !           298:        randPoolAddBytes((byte *) & t, sizeof(t));
        !           299:        delta = t - (unsigned) lastcounter;
        !           300:        lastcounter = t;
        !           301:     }
        !           302: #endif
        !           303: 
        !           304: #ifdef MACTC5
        !           305:        {
        !           306:                unsigned long t;
        !           307:                
        !           308:                delta = TMTicks();
        !           309:                t=lastcounter+=delta;
        !           310:                randPoolAddBytes((byte *)&t, sizeof(t));
        !           311:        }
        !           312: #endif
        !           313: 
        !           314: #ifdef WIN32
        !           315: /* Win32 provides QueryPerformanceCounter(), which does precisely what we need here */
        !           316:     {
        !           317:         /* What am I doing here ? : We can't #include <windows.h> to get the prototype
        !           318:            for QueryPerformanceCounter() because there are many namespace clashes
        !           319:            between PGP and windows.h. So, we hack in the prototype inline. When we get
        !           320:            a compiler which does namespaces, or someone removes all the clashes in PGP,
        !           321:            this will go.
        !           322:         */
        !           323: #if defined(_MSC_VER)  /* only valid if we're using the Microsoft compiler */
        !           324:        __declspec(dllimport) long __stdcall
        !           325:             QueryPerformanceCounter(__int64 *lpPerformanceCount);
        !           326:        unsigned t;
        !           327:        __int64 perf_count;
        !           328: 
        !           329:        QueryPerformanceCounter(&perf_count);
        !           330:        /* it doesn't matter if the return value is zero */
        !           331:        t = (unsigned) perf_count;
        !           332:        randPoolAddBytes((byte *) & t, sizeof(t));
        !           333:        delta = t - (unsigned) lastcounter;
        !           334:        lastcounter = t;
        !           335: #else  /* Not Microsoft compiler */
        !           336: #include "This compiler is not supported, modify the code above accordingly"
        !           337: #endif /* _MSC_VER */
        !           338:     }
        !           339: #endif /* WIN32 */
        !           340: 
        !           341: #ifdef VMS
        !           342:     {
        !           343:        word32 t;
        !           344:        /* VMS Hardware Clock */
        !           345:        extern unsigned long vms_clock_bits[2];
        !           346:        /* Clock update int. */
        !           347:        extern const long vms_ticks_per_update;
        !           348: 
        !           349:        /* Capture fast system timer: */
        !           350:        SYS$GETTIM(vms_clock_bits);
        !           351:        randPoolAddBytes((byte *) & vms_clock_bits, sizeof(vms_clock_bits));
        !           352:        t = vms_clock_bits[0] / vms_ticks_per_update;
        !           353:        delta = t - lastcounter;
        !           354:        lastcounter = t;
        !           355:     }
        !           356: #endif                         /* VMS */
        !           357: 
        !           358: #ifdef UNIX
        !           359:     /* Get noise from gettimeofday() */
        !           360:     {
        !           361:        struct timeval tv;
        !           362:        word32 t;
        !           363:        static unsigned ticksize = 0;
        !           364: 
        !           365:        if (!ticksize)
        !           366:            ticksize = noiseTickSize();
        !           367: 
        !           368:        gettimeofday(&tv, NULL);
        !           369:        randPoolAddBytes((byte *) & tv, sizeof(tv));
        !           370: 
        !           371:        /* This may wrap, but it's unsigned, so that's okay */
        !           372:        t = tv.tv_sec * 1000000 + tv.tv_usec;
        !           373:        delta = t - lastcounter;
        !           374:        lastcounter = t;
        !           375: 
        !           376:        delta /= ticksize;
        !           377:     }
        !           378:     /* Get noise from times() */
        !           379:     {
        !           380:        clock_t t;
        !           381:        struct tms tms;
        !           382: 
        !           383:        t = times(&tms);
        !           384:        randPoolAddBytes((byte *) & tms, sizeof(tms));
        !           385:        randPoolAddBytes((byte *) & t, sizeof(t));
        !           386:     }
        !           387: #endif                         /* UNIX */
        !           388: 
        !           389: #ifdef AMIGA     /* Whole next section added RKNOP 940613 */
        !           390: #define AMIGA_DELTAS 15
        !           391: 
        !           392:    {
        !           393:       static unsigned long ticksize = 0;
        !           394:       int i=0,j;
        !           395:       unsigned long deltas[AMIGA_DELTAS],swap;
        !           396: 
        !           397: 
        !           398:       /* NOTE -- this next section (reading the Eclock or the
        !           399:          microHz clock) will only happen within the do loop in
        !           400:          trueRandAccum()!! */
        !           401: 
        !           402:       if (TimerIO && TimerBase)
        !           403:       {  if (!ticksize)   /* Get tick size, similar to Unix */
        !           404:          {  Forbid();    /* Turn off multitasking to get ticksize */
        !           405:             if (use_eclock)
        !           406:               ReadEClock(&time0.e);
        !           407:             else
        !           408:               am_GetSysTime(&time0.t);
        !           409:             do
        !           410:             {   if (use_eclock)
        !           411:           {  ReadEClock(&time1.e);
        !           412:              if (time1.e.ev_lo>time0.e.ev_lo)
        !           413:                deltas[i++]=time1.e.ev_lo-time0.e.ev_lo;
        !           414:              time0.e.ev_lo=time1.e.ev_lo;
        !           415:              time0.e.ev_hi=time1.e.ev_hi;
        !           416:           }
        !           417:           else
        !           418:           {  am_GetSysTime(&time1.t);
        !           419:              if (CmpTime(&time0.t,&time1.t))
        !           420:                 deltas[i++]=1000000*(time1.t.tv_secs
        !           421:                       -time0.t.tv_secs)
        !           422:                   +(time1.t.tv_micro-time0.t.tv_micro);
        !           423:              time0.t.tv_secs=time1.t.tv_secs;
        !           424:              time0.t.tv_micro=time1.t.tv_micro;
        !           425:           }
        !           426:             } while (i<AMIGA_DELTAS);
        !           427:             for (i=0;i<AMIGA_DELTAS-1;i++)
        !           428:          for (j=i+1;j<AMIGA_DELTAS;j++)
        !           429:             if (deltas[j]<deltas[i])
        !           430:             {  swap=deltas[j];
        !           431:                deltas[j]=deltas[i];
        !           432:                deltas[i]=swap;
        !           433:             }
        !           434:             if ((ticksize=deltas[AMIGA_DELTAS/2])==0) ticksize=1;
        !           435:             Permit();
        !           436:          }
        !           437: 
        !           438:          if (use_eclock)
        !           439:          {  ReadEClock(&time1.e);
        !           440:             randPoolAddBytes((byte *)&time1.e.ev_lo,4);
        !           441:             delta=time1.e.ev_lo-time0.e.ev_lo;  /* wrap ok?, unsigned */
        !           442:             time0.e.ev_hi=time1.e.ev_hi;
        !           443:             time0.e.ev_lo=time1.e.ev_lo;
        !           444:          }
        !           445:          else
        !           446:          {  am_GetSysTime(&time1.t);
        !           447:             randPoolAddBytes((byte *)&time1.t,sizeof(time1.t));
        !           448:             delta=1000000*(time1.t.tv_secs - time0.t.tv_secs) +
        !           449:              time1.t.tv_micro - time0.t.tv_micro;
        !           450:             time0.t.tv_secs=time1.t.tv_secs;
        !           451:          time0.t.tv_micro=time1.t.tv_micro;
        !           452:          }
        !           453:          delta/=ticksize;
        !           454:       }
        !           455: 
        !           456:       /* Get some additional noise from the video beam poisition */
        !           457:       randPoolAddBytes((byte *)&custom.vhposr,2);
        !           458: 
        !           459:       /* Pull the ExecBase dispatch count */
        !           460:       randPoolAddBytes((byte *)
        !           461:              &((*(struct ExecBase **)4)->DispCount),4);
        !           462:    }
        !           463: #endif /* AMIGA (RKNOP 940613) */
        !           464: 
        !           465: #ifdef ATARI   /* Section written by Guy Geens <[email protected]> 951207 */
        !           466:        Supexec(getcount);      /* Xbios 38 */
        !           467:        delta=counter-lastcounter;
        !           468:        lastcounter=counter;
        !           469: 
        !           470: #ifndef __PUREC__
        !           471:        randPoolAddBytes((byte*)&counter,4);
        !           472: #endif
        !           473:        /* Under Pure C, counter is the same as cnow (returned by clock()),
        !           474:        so it doesn't add to randomness.
        !           475:        I don't have any other C compiler, so I can't check whether they
        !           476:        also use the same counter. Please mail me further details */
        !           477: 
        !           478:        randPoolAddBytes((byte*)&vblcount,4);
        !           479:        /* Other compilers might require to comment this out and activate
        !           480:        the previous line. */
        !           481: #endif         /* End of section written by Guy Geens */
        !           482: 
        !           483:     return delta;
        !           484: }

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