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Annotation of pgp/src/random.c, revision 1.1.1.9

1.1.1.9 ! root        1: /*
        !             2:  * True and cryptographic random number generation.
        !             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: #include <stdlib.h>
        !            25: #include <stdio.h>
        !            26: #include <string.h>
        !            27: #include <assert.h>
        !            28: #include <signal.h>    /* For SIGINT */
        !            29: #include <time.h>
        !            30: 
        !            31: #ifdef AMIGA      /* Includes for timer -- RKNOP */
        !            32: #include <devices/timer.h>
        !            33: #include <exec/memory.h>
        !            34: #include <exec/libraries.h>
        !            35: #include <proto/dos.h>
        !            36: #include <proto/timer.h>
        !            37: #include <proto/exec.h>
        !            38: #endif /* AMIGA */
        !            39: 
        !            40: #ifdef __PUREC__
        !            41: #include <ext.h>
        !            42: #endif
        !            43: 
        !            44: #include "system.h"    /* For ttycbreak, getch, etc. */
        !            45: #include "idea.h"
        !            46: #include "md5.h"
        !            47: #include "noise.h"
        !            48: #include "language.h"
        !            49: #include "random.h"
        !            50: #include "fileio.h"    /* For FOPRBIN */
        !            51: #include "pgp.h"       /* For globalRandseedName */
        !            52: #include "randpool.h"
        !            53: #ifdef MACTC5
        !            54: #include "Macutil2.h"
        !            55: #include "Macutil3.h"
        !            56: #include "TimeManager.h"
        !            57: #include <unix.h>
        !            58: #endif
        !            59: 
        !            60: /*
        !            61:  * As of PGP 2.6.2, the randseed.bin file has been expanded.  An explanation
        !            62:  * of how the whole thing works in in order, as people are always suspiscious
        !            63:  * of the random number generator.  (After the xorbytes bug in 2.6, perhaps
        !            64:  * you should be.)  There are two random number generators in PGP.  One
        !            65:  * is the "cryptRand" family, which is based on X9.17, but uses IDEA instead
        !            66:  * of 2-key EDE triple-DES.  This is the generator with a lot of peer review.
        !            67:  * The implementation is in idea.c.
        !            68:  * The second is the "trueRand" family, which attempt to accurately measure
        !            69:  * the entropy available from keyboard I/O.  It keeps a lot more state.
        !            70:  * The implementation of this is in randpool.c.
        !            71:  * Originally, the trueRand generator was only used for generating primes,
        !            72:  * and the cryptRand for generating IDEA session keys.  But things have
        !            73:  * become a bit more complex.  In particular, the X9.17 specification
        !            74:  * wants a source of high-resolution time-of-day information, as a source
        !            75:  * of some "true" randomness to throw in.  So we use the trueRand pool
        !            76:  * for that.
        !            77:  * The cryptRand functions keep a state file around, usually named
        !            78:  * randseed.bin, for a seed, as the X9.17 generator requires 24 bytes of
        !            79:  * known initial information.
        !            80:  * This data in this file is carefully "washed" before and after use to
        !            81:  * help ensure that if the file is captured or altered, the keys will
        !            82:  * not be too vulnerable.  A washing consists of an encryption in PGP's
        !            83:  * usual CFB mode of the material coming from or being written to the
        !            84:  * randseed.bin file on disk.  Assuming the cipher is strong, the effects
        !            85:  * of the wash are as difficult to predict as the key that is used is
        !            86:  * difficult to guess.
        !            87:  * Beforehand, we use the MD5 of the file being encrypted as an additional
        !            88:  * source of randomness (on the theory that an attacker trying to break
        !            89:  * a session key probably doesn't have the plaintext, or he wouldn't need
        !            90:  * to bother), and use that as an IDEA key (with a fixed IV of zero)
        !            91:  * to encrypt the randseed.bin data.
        !            92:  * After generating an IDEA key and IV, some more random bytes are generated
        !            93:  * to reinitialize randseed.bin, and these are encrypted in the same manner
        !            94:  * as the PGP message before being written to disk, on the assumption that
        !            95:  * if an attacker can decrypt that, they can decrypt the message directly
        !            96:  * and not bother attacking the randseed.bin file.
        !            97:  * The previous code only saved the 24 bytes needed by the X9.17 algorithm.
        !            98:  * But in 2.6.2, we decided to make the randseed.bin file substantially
        !            99:  * larger to hold more information that a would-be attacker must guess.
        !           100:  * There are two reasons for this:
        !           101:  * - Every time you run PGP, especially when responding to one of PGP's
        !           102:  *   prompts, PGP samples the keystrokes for use as random numbers.
        !           103:  *   It is a shame to throw this entropy (randomness) away just because
        !           104:  *   there is no need for it in the current invocation of PGP.
        !           105:  * - A feature was added to 2.6.2 to generate files full of random bytes
        !           106:  *   for other programs to use as key material.  In this case, we haven't
        !           107:  *   got a message we're encrypting to take some entropy from, and we may
        !           108:  *   be asked to generate more than 24 random bytes, so there should be
        !           109:  *   more than 24 bytes of seed material to work from.
        !           110:  * The implementation is added on to the previous one, to offer assurance
        !           111:  * that it is no weaker.
        !           112:  * When the cryptRand generator is opened, the file is washed (if possible)
        !           113:  * and the first 24 bytes are fed to the cryptographic RNG, while the
        !           114:  * remainder is added to the trueRand random number pool.
        !           115:  * When saving, the randseed.bin file is refilled with newly generated
        !           116:  * bytes, again washed if possible.  It turns out (if you study the
        !           117:  * X9.17 RNG) that each of the 2^64 possible timestamp information
        !           118:  * values used in generating each 8 bytes of output generates a output
        !           119:  * value, so the entropy in the trueRand pool is put to good use; this
        !           120:  * is not just generating more data from 24 bytes of seed.
        !           121:  * The random pool is opened and saved with a washing key when
        !           122:  * generating a session key (see make_random_ideakey in crypto.c),
        !           123:  * but it is also opened (harmless if alreasy open) and saved
        !           124:  * (harmless if already saved) without a washing key in the exitPGP routine,
        !           125:  * to mix in any entropy collected in this invocation of PGP even if
        !           126:  * a session key was not generated.
        !           127:  */
        !           128: 
        !           129: /*
        !           130:  * The new randseed size, big enough to hold the full context of the cryptRand
        !           131:  * and trueRand generators.  With the current RANDPOOLBITS of 3072 (384 bytes),
        !           132:  * that's 408 bytes.  It's useless to make it any larger, although if
        !           133:  * RANDPOOLBITS is increased, it might be an idea to keep this smaller than
        !           134:  * one disk block on all systems (512 bytes is a good figure to use)
        !           135:  * so we don't change the space requirements for randseed.bin.
        !           136:  */
        !           137: #define RANDSEED_BYTES (RANDPOOLBITS/8 + 24)
        !           138: /* Have we read in the randseed.bin file? */
        !           139: static boolean randSeedOpen = 0;
        !           140: static struct IdeaRandContext randContext;
        !           141: 
        !           142: /*
        !           143:  * Load the RNG state from the randseed.bin file on disk.
        !           144:  * Returns 0 on success, <0 on error.
        !           145:  *
        !           146:  * If cfb is non-zero, prewashes the data by encrypting with it.
        !           147:  */
        !           148: int
        !           149: cryptRandOpen(struct IdeaCfbContext *cfb)
        !           150: {
        !           151:        byte buf[256];
        !           152:        int len;
        !           153:        FILE *f;
        !           154: 
        !           155:        if (randSeedOpen)
        !           156:                return 0;       /* Already open */
        !           157: 
        !           158:        f = fopen(globalRandseedName, FOPRBIN);
        !           159:        if (!f)
        !           160:                return -1;
        !           161: 
        !           162:        /* First get the bare minimum 24 bytes we need for the IDEA RNG */
        !           163:        len = fread((char *)buf, 1, 24, f);
        !           164:        if (cfb)
        !           165:                ideaCfbEncrypt(cfb, buf, buf, 24);
        !           166:        ideaRandInit(&randContext, buf, buf+16);
        !           167:        randSeedOpen = TRUE;
        !           168:        if (len != 24) { /* Error */
        !           169:                fclose(f);
        !           170:                return -1;
        !           171:        }
        !           172: 
        !           173:        /* Read any extra into the random pool */
        !           174:        for (;;) {
        !           175:                len = fread((char *)buf, 1, sizeof(buf), f);
        !           176:                if (len <= 0)
        !           177:                        break;
        !           178:                if (cfb)
        !           179:                        ideaCfbEncrypt(cfb, buf, buf, len);
        !           180:                randPoolAddBytes(buf, len);
        !           181:        }
        !           182: 
        !           183:        fclose(f);
        !           184:        burn(buf);
        !           185: #ifdef MACTC5
        !           186:        PGPSetFinfo(globalRandseedName,'RSed','MPGP');
        !           187: #endif
        !           188:        return 0;
        !           189: }
        !           190: 
        !           191: /* Create a new state from the output of trueRandByte */
        !           192: void
        !           193: cryptRandInit(struct IdeaCfbContext *cfb)
        !           194: {
        !           195:        byte buf[24];
        !           196:        int i;
        !           197: 
        !           198:        for (i = 0; i < sizeof(buf); i++)
        !           199:                buf[i] = trueRandByte();
        !           200:        if (cfb)
        !           201:                ideaCfbEncrypt(cfb, buf, buf, sizeof(buf));
        !           202: 
        !           203:        ideaRandInit(&randContext, buf, buf+16);
        !           204:        randSeedOpen = TRUE;
        !           205:        burn(buf);
        !           206: }
        !           207: 
        !           208: byte
        !           209: cryptRandByte(void)
        !           210: {
        !           211:        if (!randSeedOpen)
        !           212:                cryptRandOpen((struct IdeaCfbContext *)0);
        !           213:        return ideaRandByte(&randContext);
        !           214: }
        !           215: 
        !           216: /*
        !           217:  * Write out a file of random bytes.  If cfb is defined, wash it with the
        !           218:  * cipher.
        !           219:  */
        !           220: int
        !           221: cryptRandWriteFile(char const *name, struct IdeaCfbContext *cfb, unsigned bytes)
        !           222: {
        !           223:        byte buf[256];
        !           224:        FILE *f;
        !           225:        int i, len;
        !           226: 
        !           227:        f = fopen(name, FOPWBIN);
        !           228:        if (!f)
        !           229:                return -1;
        !           230: 
        !           231:        while (bytes) {
        !           232:                len = (bytes < sizeof(buf)) ? bytes : sizeof(buf);
        !           233:                for (i = 0; i < len; i++)
        !           234:                        buf[i] = ideaRandByte(&randContext);
        !           235:                if (cfb)
        !           236:                        ideaCfbEncrypt(cfb, buf, buf, len);
        !           237:                i = fwrite(buf, 1, len, f);
        !           238:                if (i < len)
        !           239:                        break;
        !           240:                bytes -= len;
        !           241:        }
        !           242: 
        !           243: #ifdef MACTC5
        !           244:        PGPSetFinfo((char *)name,'RSed','MPGP');
        !           245: #endif
        !           246: 
        !           247:        return (fclose(f) != 0 || bytes != 0) ? -1 : 0;
        !           248: }
        !           249: 
        !           250: /*
        !           251:  * Create a new RNG state, encrypt it with the supplied key, and save it
        !           252:  * out to disk.
        !           253:  *
        !           254:  * When we encrypt a file, the saved data is "postwashed" using the
        !           255:  * same key and initial vector (including the repeated check bytes and
        !           256:  * everything) that is used to encrypt the user's message.
        !           257:  * The hope is that this "postwash" renders it is at least as hard to
        !           258:  * derive old session keys from randseed.bin as it is to crack the the
        !           259:  * message directly.
        !           260:  *
        !           261:  * The purpose of using EXACTLY the same encryption is to make sure that
        !           262:  * there isn't related, but different data floating around that can be
        !           263:  * used for cryptanalysis.
        !           264:  *
        !           265:  * This function is always called by exitPGP, without a washing encryption,
        !           266:  * so this function ignores that call if it has previously been called
        !           267:  * to save washed bytes.
        !           268:  */
        !           269: #ifdef MACTC5
        !           270:        boolean savedwashed = FALSE;
        !           271: #endif
        !           272: 
        !           273: void
        !           274: cryptRandSave(struct IdeaCfbContext *cfb)
        !           275: {
        !           276: #ifndef MACTC5
        !           277:        static boolean savedwashed = FALSE;
        !           278: #endif
        !           279: 
        !           280:        if (!randSeedOpen)
        !           281:                return; /* Do nothing */
        !           282: 
        !           283:        if (cfb)
        !           284:                savedwashed = TRUE;
        !           285:        else if (savedwashed)
        !           286:                return; /* Don't re-save if it's already been saved washed. */
        !           287: 
        !           288:        (void)cryptRandWriteFile(globalRandseedName, cfb, RANDSEED_BYTES);
        !           289: #ifdef MACTC5
        !           290:        PGPSetFinfo(globalRandseedName,'RSed','MPGP');
        !           291: #endif
        !           292: }
        !           293: 
        !           294: /*
        !           295:  * True random bit handling
        !           296:  */
        !           297: 
        !           298: /*
        !           299:  * Because these truly random bytes are so unwieldy to accumulate,
        !           300:  * they can be regarded as a precious resource.  Unfortunately,
        !           301:  * cryptographic key generation algorithms may require a great many
        !           302:  * random bytes while searching about for large random prime numbers.
        !           303:  * Fortunately, they need not all be truly random.  We only need as
        !           304:  * many truly random bits as there are bits in the large prime we
        !           305:  * are searching for.  These random bytes can be recycled and modified
        !           306:  * via pseudorandom numbers until the key is generated, without losing
        !           307:  * any of the integrity of randomness of the final key.
        !           308:  *
        !           309:  * The technique used is a pool of random numbers, which bytes are
        !           310:  * taken from successively and, when the end is reached, the pool
        !           311:  * is stirred using an irreversible hash function.  Some (64 bytes)
        !           312:  * of the pool is not returned to ensure the sequence is not predictible
        !           313:  * from the values retriefed from trueRandByte().  To be precise,
        !           314:  * MD5Transform is used as a block cipher in CBC mode, and then the
        !           315:  * "key" (i.e. what is usually the material to be hashed) is overwritten
        !           316:  * with some of the just-generated random bytes.
        !           317:  *
        !           318:  * This is implemented in randpool.c; see that file for details.
        !           319:  *
        !           320:  * An estimate of the number of bits of true (Shannon) entropy in the
        !           321:  * pool is kept in trueRandBits.  This is incremented when timed
        !           322:  * keystrokes are available, and decremented when bits are explicitly
        !           323:  * consumed for some purpose (such as prime generation) or another.
        !           324:  *
        !           325:  * trueRandFlush is called to obliterate traces of old random bits after
        !           326:  * prime generation is completed.  (Primes are the most carefully-guarded
        !           327:  * values in PGP.)
        !           328:  */
        !           329: 
        !           330: static unsigned trueRandBits = 0;      /* Bits of entropy in pool */
        !           331: 
        !           332: #ifdef MACTC5
        !           333: #define CBITS 5
        !           334: #define TRByt 3
        !           335: #define TREvt 1
        !           336: 
        !           337: static void perturb(rbits)
        !           338: int rbits;
        !           339: {      
        !           340:        spinner();
        !           341:        randPoolAddBytes((byte *) seedBuffer, 8);
        !           342:        trueRandBits +=rbits;
        !           343:        if (trueRandBits > RANDPOOLBITS)
        !           344:                trueRandBits = RANDPOOLBITS;
        !           345:        return;
        !           346: }
        !           347: #endif
        !           348: 
        !           349: /* trueRandPending is bits to add to next accumulation request */
        !           350: static unsigned trueRandPending = 0;
        !           351: 
        !           352: /*
        !           353:  * Destroys already-used random numbers.  Ensures no sensitive data
        !           354:  * remains in memory that can be recovered later.  This is called
        !           355:  * after RSA key generation, so speed is not critical, but security is.
        !           356:  * RSA key generation takes long enough that interrupts and other
        !           357:  * tasks are likely to have used a measurable and difficult-to-predict
        !           358:  * amount of real time, so there is some virtue in sampling the clocks
        !           359:  * with noise().
        !           360:  */
        !           361: void
        !           362: trueRandFlush(void)
        !           363: {
        !           364:        noise();
        !           365:        randPoolStir(); /* Destroy evidence of what primes were generated */
        !           366:        randPoolStir();
        !           367:        randPoolStir();
        !           368:        randPoolStir(); /* Make *really* certain */
        !           369: }
        !           370: 
        !           371: /*
        !           372:  * "Consumes" count bits worth of entropy from the true random pool for some
        !           373:  * purpose, such as prime generation.
        !           374:  *
        !           375:  * Note that something like prime generation can end up calling trueRandByte
        !           376:  * more often than is implied by the count passed to trueRandClaim; this
        !           377:  * may happen if the random bit consumer is not perfectly efficient in its
        !           378:  * use of random bits.  For example, if a search for a suitable prime fails,
        !           379:  * the easiest thing to do is to get another load of random bits and try
        !           380:  * again.  It is perfectly acceptable if these bits are correlated with the
        !           381:  * bits used in the failed attempt, since they are discarded.
        !           382:  */
        !           383: void
        !           384: trueRandConsume(unsigned count)
        !           385: {
        !           386: #ifdef MACTC5
        !           387:        if( trueRandBits >= count )
        !           388:                trueRandBits -= count;
        !           389:        else
        !           390:                trueRandBits = 0;
        !           391: #else
        !           392:        assert (trueRandBits >= count);
        !           393:        trueRandBits -= count;
        !           394: #endif
        !           395: }
        !           396: 
        !           397: /*
        !           398:  * Returns a truly random byte if any are available.  It degenerates to
        !           399:  * a pseudorandom value if there are none.  It is not an error to call
        !           400:  * this if none are available.  For example, it is called when generating
        !           401:  * session keys to add to other sources of cryptographic random numbers.
        !           402:  *
        !           403:  * This forces an accumulation if any extra random bytes are pending.
        !           404:  */
        !           405: int
        !           406: trueRandByte(void)
        !           407: {
        !           408:        if (trueRandPending)
        !           409:                trueRandAccum(0);
        !           410: #ifdef MACTC5
        !           411:        while( trueRandBits < 8 ) {
        !           412:                perturb(TRByt);
        !           413:                spinner();
        !           414:                }
        !           415: #endif
        !           416: 
        !           417:        return randPoolGetByte();
        !           418: }
        !           419: 
        !           420: /*
        !           421:  * Given an event (typically a keystroke) coded by "event"
        !           422:  * at a random time, add all randomness to the random pool,
        !           423:  * compute a (conservative) estimate of the amount, add it
        !           424:  * to the pool, and return the amount of randomness.
        !           425:  * (The return value is just for informational purposes.)
        !           426:  *
        !           427:  * Double events are okay, but three in a row is considered
        !           428:  * suspiscous and the randomness is counted as 0.
        !           429:  */
        !           430: unsigned
        !           431: trueRandEvent(int event)
        !           432: {
        !           433:        static int event1 = 0, event2 = 0;
        !           434:        word32 delta;
        !           435:        unsigned cbits;
        !           436: 
        !           437:        delta = noise();
        !           438:        randPoolAddBytes((byte *)&event, sizeof(event));
        !           439: 
        !           440: #ifdef MACTC5
        !           441:        perturb(TRByt);
        !           442: #endif
        !           443: 
        !           444:        if (event == event1 && event == event2) {
        !           445:                cbits = 0;
        !           446:        } else {
        !           447:                event2 = event1;
        !           448:                event1 = event;
        !           449: 
        !           450:                for (cbits = 0; delta; cbits++)
        !           451:                        delta >>= 1;
        !           452: 
        !           453:                /* Excessive paranoia? */
        !           454: #ifdef MACTC5
        !           455:                if (cbits > CBITS)
        !           456:                        cbits = CBITS;
        !           457: #else
        !           458:                if (cbits > 8)
        !           459:                        cbits = 8;
        !           460: #endif
        !           461:        }
        !           462: 
        !           463:        trueRandBits += cbits;
        !           464:        if (trueRandBits > RANDPOOLBITS)
        !           465:                trueRandBits = RANDPOOLBITS;
        !           466: 
        !           467:        return cbits;
        !           468: }
        !           469: 
        !           470: 
        !           471: /*
        !           472:  * Since getting random bits from the keyboard requires user attention,
        !           473:  * we buffer up requests for them until we can do one big request.
        !           474:  */
        !           475: void
        !           476: trueRandAccumLater(unsigned bitcount)
        !           477: {
        !           478:        trueRandPending += bitcount;    /* Wow, that was easy! :-) */
        !           479: #ifdef MACTC5
        !           480:        spinner();
        !           481: #endif
        !           482: }
        !           483: 
        !           484: static void flush_input(void);
        !           485: 
        !           486: #ifdef AMIGA  /* Globals used for timing here and in noise.c - RKNOP 940613 */
        !           487: struct Library *TimerBase=NULL;
        !           488: struct timerequest *TimerIO=NULL;
        !           489: union { struct timeval t;
        !           490:         struct EClockVal e;
        !           491:       } time0,time1;
        !           492: unsigned short use_eclock=0;
        !           493: #endif /* AMIGA */
        !           494: 
        !           495: /*
        !           496:  * Performs an accumulation of random bits.  As long as there are fewer bits
        !           497:  * in the buffer than are needed (the number passed, plus pending bits),
        !           498:  * prompt for more.
        !           499:  */
        !           500: void
        !           501: trueRandAccum(unsigned count)  /* Get this many random bits ready */
        !           502: {
        !           503:        int c;
        !           504: #if defined(MSDOS) || defined(__MSDOS__)
        !           505:        time_t timer;
        !           506: #endif
        !           507: 
        !           508:        count += trueRandPending;       /* Do deferred accumulation now */
        !           509:        trueRandPending = 0;
        !           510: 
        !           511:        if (count > RANDPOOLBITS)
        !           512:                count = RANDPOOLBITS;
        !           513: 
        !           514:        if (trueRandBits >= count)
        !           515:                return;
        !           516: 
        !           517:        fprintf(stderr,
        !           518: LANG("\nWe need to generate %u random bits.  This is done by measuring the\
        !           519: \ntime intervals between your keystrokes.  Please enter some random text\
        !           520: \non your keyboard until you hear the beep:\n"), count-trueRandBits);
        !           521: 
        !           522:        ttycbreak();
        !           523: 
        !           524: #ifdef AMIGA  /* RKNOP 940613 */
        !           525:         TimerIO=(struct timerequest *)AllocMem(sizeof(struct timerequest),
        !           526:                                                MEMF_PUBLIC|MEMF_CLEAR);
        !           527:         if (TimerIO)
        !           528:         {  if (OpenDevice(TIMERNAME,UNIT_MICROHZ,(struct IORequest *)TimerIO,0))
        !           529:               TimerBase=NULL;
        !           530:            else
        !           531:            {  TimerBase=(struct Library *)TimerIO->tr_node.io_Device;
        !           532:               if (TimerBase->lib_Version>=36) /* Use E-clock instead */
        !           533:               {  use_eclock=1;
        !           534:                  CloseDevice((struct IORequest *)TimerIO);
        !           535:                  if (!OpenDevice(TIMERNAME,UNIT_ECLOCK,
        !           536:                                  (struct IORequest *)TimerIO,0))
        !           537:                     TimerBase=(struct Library *)TimerIO->tr_node.io_Device;
        !           538:                  else
        !           539:                     TimerBase=NULL;
        !           540:               }
        !           541:               else use_eclock=0;
        !           542:            }
        !           543:         }
        !           544:         else TimerBase=NULL;
        !           545: #endif /* AMIGA */
        !           546: 
        !           547:        do {
        !           548:                /* display counter to show progress */
        !           549:                fprintf(stderr,"\r%4d ", count-trueRandBits);
        !           550:                fflush(stderr); /* assure screen update */
        !           551: 
        !           552:                flush_input();  /* If there's no delay, we can't use it */
        !           553: #ifdef MACTC5
        !           554:                StartTMCounter();
        !           555: #endif
        !           556:                c = getch();    /* always wait for input */
        !           557: #ifdef MSDOS
        !           558:                if (c == 3)
        !           559:                        breakHandler(SIGINT);
        !           560:                if (c == 0)
        !           561:                        c = getch() + 256;
        !           562: #endif
        !           563:                /* Print flag indicating acceptance (or not) */
        !           564:                 /* putc a macro, not safe to have function as an arg!! */
        !           565:                 fputc(trueRandEvent(c) ? '.' : '?' , stderr);
        !           566: #ifdef MACTC5
        !           567:                StopTMCounter();
        !           568: #endif
        !           569:        } while (trueRandBits < count);
        !           570: 
        !           571:        fputs("\r   0 *", stderr);
        !           572:        fputs(LANG("\007 -Enough, thank you.\n"), stderr);
        !           573: 
        !           574: #if defined(MSDOS) || defined(__MSDOS__)
        !           575:        /* Wait until one full second has passed without keyboard input */
        !           576:        do {
        !           577:                flush_input();
        !           578:                sleep(1);
        !           579:        } while (kbhit());
        !           580: #else
        !           581: #ifdef AMIGA       /* Added RKNOP 940608 */
        !           582:         Delay(50*1);    /* dos.library function, wait 1 second */
        !           583:         if (TimerBase) CloseDevice((struct IORequest *)TimerIO);
        !           584:         TimerBase=NULL;
        !           585:         if (TimerIO) FreeMem(TimerIO,sizeof(struct timerequest));
        !           586:         TimerIO=NULL;
        !           587: #else
        !           588:        sleep(1);
        !           589:        flush_input();
        !           590: #endif
        !           591: #endif
        !           592: 
        !           593:        ttynorm();
        !           594: }
        !           595: 
        !           596: #ifndef EBCDIC                   /* already defined in usuals.h */
        !           597: #define BS 8
        !           598: #define LF 10
        !           599: #define CR 13
        !           600: #define DEL 127
        !           601: #endif
        !           602: 
        !           603: #ifdef VMS
        !           604: int putch(int);
        !           605: #else
        !           606: #define putch(c) putc(c, stderr)
        !           607: #endif
        !           608: 
        !           609: int
        !           610: getstring(char *strbuf, unsigned maxlen, int echo)
        !           611: /* Gets string from user, with no control characters allowed.
        !           612:  * Also accumulates random numbers.
        !           613:  * maxlen is max length allowed for string.
        !           614:  * echo is TRUE iff we should echo keyboard to screen.
        !           615:  * Returns null-terminated string in strbuf.
        !           616:  */
        !           617: {
        !           618:        unsigned i;
        !           619:        char c;
        !           620: 
        !           621:        ttycbreak();
        !           622: 
        !           623: #ifdef AMIGA     /* In case of -f (use stdio for plaintext input),
        !           624:                     use ReqTools for input from the user */
        !           625:         if (!IsInteractive(Input()))
        !           626:            return AmigaRequestString(strbuf,maxlen,echo);
        !           627: #endif
        !           628: 
        !           629:        fflush(stdout);
        !           630:        i=0;
        !           631:        for (;;) {
        !           632: #ifndef VMS
        !           633:                fflush(stderr);
        !           634: #endif /* VMS */
        !           635:                c = getch();
        !           636:                trueRandEvent(c);
        !           637: #ifdef VMS
        !           638:                if (c == 25) {  /*  Control-Y detected */
        !           639:                    ttynorm();
        !           640:                    breakHandler(SIGINT);
        !           641:                }
        !           642: #endif /* VMS */
        !           643: #if defined(MSDOS) || defined (__MSDOS__)
        !           644:                if (c == 3)
        !           645:                        breakHandler(SIGINT);
        !           646: #endif
        !           647:                if (c==BS || c==DEL) {
        !           648:                        if (i) {
        !           649:                                if (echo) {
        !           650:                                        putch(BS);
        !           651:                                        putch(' ');
        !           652:                                        putch(BS);
        !           653:                                }
        !           654:                                i--;
        !           655:                        } else {
        !           656:                                putch('\007');
        !           657:                        }
        !           658:                        continue;
        !           659:                }
        !           660:                if (c < ' ' && c != LF && c != CR) {
        !           661:                        putch('\007');
        !           662: #if defined(MSDOS) || defined (__MSDOS__)
        !           663:                        if (c == 3)
        !           664:                                breakHandler(SIGINT);   
        !           665:                        if (c == 0)
        !           666:                                getch(); /* Skip extended key codes */
        !           667: #endif
        !           668:                        continue;
        !           669:                }
        !           670:                if (echo)
        !           671:                        putch(c);
        !           672:                if (c==CR) {
        !           673:                        if (echo)
        !           674:                                putch(LF);
        !           675:                        break;
        !           676:                }
        !           677:                if (c==LF)
        !           678:                        break;
        !           679:                if (c=='\n')
        !           680:                        break;
        !           681:                strbuf[i++] = c;
        !           682:                if (i >= maxlen) {
        !           683:                        fputs("\007*\n", stderr);       /* -Enough! */
        !           684: #if 0
        !           685:                        while (kbhit())
        !           686:                                getch();        /* clean up any typeahead */
        !           687: #endif
        !           688:                        break;
        !           689:                }
        !           690:        }
        !           691:        strbuf[i] = '\0';       /* null termination of string */
        !           692: 
        !           693:        ttynorm();
        !           694: 
        !           695:        return(i);              /* returns string length */
        !           696: } /* getstring */
        !           697: 
        !           698: 
        !           699: static void
        !           700: flush_input(void)
        !           701: {      /* on unix ttycbreak() will flush the input queue */
        !           702: #if defined(MSDOS) || defined (__MSDOS__) || defined(MACTC5)
        !           703:        while (kbhit()) /* flush typahead buffer */
        !           704:                getch();
        !           705: #endif
        !           706: }

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