granicus.if.org Git - imagemagick/blob - MagickCore/random.c

   1 /*
   2 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   3 %                                                                             %
   4 %                                                                             %
   5 %                 RRRR    AAA   N   N  DDDD    OOO   M   M                    %
   6 %                 R   R  A   A  NN  N  D   D  O   O  MM MM                    %
   7 %                 RRRR   AAAAA  N N N  D   D  O   O  M M M                    %
   8 %                 R R    A   A  N  NN  D   D  O   O  M   M                    %
   9 %                 R  R   A   A  N   N  DDDD    OOO   M   M                    %
  10 %                                                                             %
  11 %                                                                             %
  12 %               MagickCore Methods to Generate Random Numbers                 %
  13 %                                                                             %
  14 %                             Software Design                                 %
  15 %                               John Cristy                                   %
  16 %                              December 2001                                  %
  17 %                                                                             %
  18 %                                                                             %
  19 %  Copyright 1999-2012 ImageMagick Studio LLC, a non-profit organization      %
  20 %  dedicated to making software imaging solutions freely available.           %
  21 %                                                                             %
  22 %  You may not use this file except in compliance with the License.  You may  %
  23 %  obtain a copy of the License at                                            %
  24 %                                                                             %
  25 %    http://www.imagemagick.org/script/license.php                            %
  26 %                                                                             %
  27 %  Unless required by applicable law or agreed to in writing, software        %
  28 %  distributed under the License is distributed on an "AS IS" BASIS,          %
  29 %  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
  30 %  See the License for the specific language governing permissions and        %
  31 %  limitations under the License.                                             %
  32 %                                                                             %
  33 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  34 %
  35 %  The generation of random numbers is too important to be left to chance.
  36 %                               -- Tom Christiansen <tchrist@mox.perl.com>
  37 %
  38 %
  39 */
  40 \f
  41 /*
  42   Include declarations.
  43 */
  44 #if defined(__VMS)
  45 #include <time.h>
  46 #endif
  47 #if defined(__MINGW32__)
  48 #include <sys/time.h>
  49 #endif
  50 #include "MagickCore/studio.h"
  51 #include "MagickCore/exception.h"
  52 #include "MagickCore/exception-private.h"
  53 #include "MagickCore/memory_.h"
  54 #include "MagickCore/semaphore.h"
  55 #include "MagickCore/random_.h"
  56 #include "MagickCore/random-private.h"
  57 #include "MagickCore/resource_.h"
  58 #include "MagickCore/signature-private.h"
  59 #include "MagickCore/string_.h"
  60 #include "MagickCore/thread_.h"
  61 #include "MagickCore/thread-private.h"
  62 #include "MagickCore/utility.h"
  63 #include "MagickCore/utility-private.h"
  64 /*
  65   Define declarations.
  66 */
  67 #define PseudoRandomHash  SHA256Hash
  68 #define RandomEntropyLevel  9
  69 #define RandomFilename  "reservoir.xdm"
  70 #define RandomFiletype  "random"
  71 #define RandomProtocolMajorVersion  1
  72 #define RandomProtocolMinorVersion  0
  73 \f
  74 /*
  75   Typedef declarations.
  76 */
  77 struct _RandomInfo
  78 {
  79   SignatureInfo
  80     *signature_info;
  81
  82   StringInfo
  83     *nonce,
  84     *reservoir;
  85
  86   size_t
  87     i;
  88
  89   unsigned long
  90     seed[4];
  91
  92   double
  93     normalize;
  94
  95   unsigned short
  96     protocol_major,
  97     protocol_minor;
  98
  99   SemaphoreInfo
 100     *semaphore;
 101
 102   ssize_t
 103     timestamp;
 104
 105   size_t
 106     signature;
 107 };
 108 \f
 109 /*
 110   External declarations.
 111 */
 112 #if defined(__APPLE__) && !defined(TARGET_OS_IPHONE)
 113 #include <crt_externs.h>
 114 #define environ (*_NSGetEnviron())
 115 #endif
 116
 117 extern char
 118   **environ;
 119 \f
 120 /*
 121   Global declarations.
 122 */
 123 static SemaphoreInfo
 124   *random_semaphore = (SemaphoreInfo *) NULL;
 125
 126 static unsigned long
 127   random_seed = ~0UL;
 128
 129 static MagickBooleanType
 130   gather_true_random = MagickFalse;
 131 \f
 132 /*
 133   Forward declarations.
 134 */
 135 static StringInfo
 136   *GenerateEntropicChaos(RandomInfo *);
 137 \f
 138 /*
 139 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 140 %                                                                             %
 141 %                                                                             %
 142 %                                                                             %
 143 %   A c q u i r e R a n d o m I n f o                                         %
 144 %                                                                             %
 145 %                                                                             %
 146 %                                                                             %
 147 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 148 %
 149 %  AcquireRandomInfo() allocates the RandomInfo structure.
 150 %
 151 %  The format of the AcquireRandomInfo method is:
 152 %
 153 %      RandomInfo *AcquireRandomInfo(void)
 154 %
 155 */
 156
 157 static inline size_t MagickMin(const size_t x,const size_t y)
 158 {
 159   if (x < y)
 160     return(x);
 161   return(y);
 162 }
 163
 164 MagickExport RandomInfo *AcquireRandomInfo(void)
 165 {
 166   const StringInfo
 167     *digest;
 168
 169   RandomInfo
 170     *random_info;
 171
 172   StringInfo
 173     *entropy,
 174     *key,
 175     *nonce;
 176
 177   random_info=(RandomInfo *) AcquireMagickMemory(sizeof(*random_info));
 178   if (random_info == (RandomInfo *) NULL)
 179     ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
 180   (void) ResetMagickMemory(random_info,0,sizeof(*random_info));
 181   random_info->signature_info=AcquireSignatureInfo();
 182   random_info->nonce=AcquireStringInfo(2*GetSignatureDigestsize(
 183     random_info->signature_info));
 184   ResetStringInfo(random_info->nonce);
 185   random_info->reservoir=AcquireStringInfo(GetSignatureDigestsize(
 186     random_info->signature_info));
 187   ResetStringInfo(random_info->reservoir);
 188   random_info->normalize=1.0/(~0UL);
 189   random_info->semaphore=AllocateSemaphoreInfo();
 190   random_info->protocol_major=RandomProtocolMajorVersion;
 191   random_info->protocol_minor=RandomProtocolMinorVersion;
 192   random_info->timestamp=(ssize_t) time(0);
 193   random_info->signature=MagickSignature;
 194   /*
 195     Seed random nonce.
 196   */
 197   nonce=GenerateEntropicChaos(random_info);
 198   if (nonce == (StringInfo *) NULL)
 199     ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
 200   InitializeSignature(random_info->signature_info);
 201   UpdateSignature(random_info->signature_info,nonce);
 202   FinalizeSignature(random_info->signature_info);
 203   SetStringInfoLength(nonce,(GetSignatureDigestsize(
 204     random_info->signature_info)+1)/2);
 205   SetStringInfo(nonce,GetSignatureDigest(random_info->signature_info));
 206   SetStringInfo(random_info->nonce,nonce);
 207   nonce=DestroyStringInfo(nonce);
 208   /*
 209     Seed random reservoir with entropic data.
 210   */
 211   entropy=GenerateEntropicChaos(random_info);
 212   if (entropy == (StringInfo *) NULL)
 213     ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
 214   UpdateSignature(random_info->signature_info,entropy);
 215   FinalizeSignature(random_info->signature_info);
 216   SetStringInfo(random_info->reservoir,GetSignatureDigest(
 217     random_info->signature_info));
 218   entropy=DestroyStringInfo(entropy);
 219   /*
 220     Seed pseudo random number generator.
 221   */
 222   if (random_seed == ~0UL)
 223     {
 224       key=GetRandomKey(random_info,sizeof(random_seed));
 225       (void) CopyMagickMemory(random_info->seed,GetStringInfoDatum(key),
 226         GetStringInfoLength(key));
 227       key=DestroyStringInfo(key);
 228     }
 229   else
 230     {
 231       SignatureInfo
 232         *signature_info;
 233
 234       signature_info=AcquireSignatureInfo();
 235       key=AcquireStringInfo(sizeof(random_seed));
 236       SetStringInfoDatum(key,(unsigned char *) &random_seed);
 237       UpdateSignature(signature_info,key);
 238       key=DestroyStringInfo(key);
 239       FinalizeSignature(signature_info);
 240       digest=GetSignatureDigest(signature_info);
 241       (void) CopyMagickMemory(random_info->seed,GetStringInfoDatum(digest),
 242         MagickMin(GetSignatureDigestsize(signature_info),
 243         sizeof(*random_info->seed)));
 244       signature_info=DestroySignatureInfo(signature_info);
 245     }
 246   random_info->seed[1]=0x50a7f451UL;
 247   random_info->seed[2]=0x5365417eUL;
 248   random_info->seed[3]=0xc3a4171aUL;
 249   return(random_info);
 250 }
 251 \f
 252 /*
 253 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 254 %                                                                             %
 255 %                                                                             %
 256 %                                                                             %
 257 +   D e s t r o y R a n d o m I n f o                                         %
 258 %                                                                             %
 259 %                                                                             %
 260 %                                                                             %
 261 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 262 %
 263 %  DestroyRandomInfo() deallocates memory associated with the random
 264 %  reservoir.
 265 %
 266 %  The format of the DestroyRandomInfo method is:
 267 %
 268 %      RandomInfo *DestroyRandomInfo(RandomInfo *random_info)
 269 %
 270 %  A description of each parameter follows:
 271 %
 272 %    o random_info: the random info.
 273 %
 274 */
 275 MagickExport RandomInfo *DestroyRandomInfo(RandomInfo *random_info)
 276 {
 277   (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
 278   assert(random_info != (RandomInfo *) NULL);
 279   assert(random_info->signature == MagickSignature);
 280   LockSemaphoreInfo(random_info->semaphore);
 281   if (random_info->reservoir != (StringInfo *) NULL)
 282     random_info->reservoir=DestroyStringInfo(random_info->reservoir);
 283   if (random_info->nonce != (StringInfo *) NULL)
 284     random_info->nonce=DestroyStringInfo(random_info->nonce);
 285   if (random_info->signature_info != (SignatureInfo *) NULL)
 286     random_info->signature_info=DestroySignatureInfo(
 287       random_info->signature_info);
 288   (void) ResetMagickMemory(random_info->seed,0,sizeof(*random_info->seed));
 289   random_info->signature=(~MagickSignature);
 290   UnlockSemaphoreInfo(random_info->semaphore);
 291   DestroySemaphoreInfo(&random_info->semaphore);
 292   random_info=(RandomInfo *) RelinquishMagickMemory(random_info);
 293   return(random_info);
 294 }
 295 \f
 296 /*
 297 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 298 %                                                                             %
 299 %                                                                             %
 300 %                                                                             %
 301 +   G e n e r a t e E n t r o p i c C h a o s                                 %
 302 %                                                                             %
 303 %                                                                             %
 304 %                                                                             %
 305 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 306 %
 307 %  GenerateEntropicChaos() generate entropic chaos used to initialize the
 308 %  random reservoir.
 309 %
 310 %  The format of the GenerateEntropicChaos method is:
 311 %
 312 %      StringInfo *GenerateEntropicChaos(RandomInfo *random_info)
 313 %
 314 %  A description of each parameter follows:
 315 %
 316 %    o random_info: the random info.
 317 %
 318 */
 319
 320 #if !defined(MAGICKCORE_WINDOWS_SUPPORT)
 321 static ssize_t ReadRandom(int file,unsigned char *source,size_t length)
 322 {
 323   register unsigned char
 324     *q;
 325
 326   ssize_t
 327     offset,
 328     count;
 329
 330   offset=0;
 331   for (q=source; length != 0; length-=count)
 332   {
 333     count=(ssize_t) read(file,q,length);
 334     if (count <= 0)
 335       {
 336         count=0;
 337         if (errno == EINTR)
 338           continue;
 339         return(-1);
 340       }
 341     q+=count;
 342     offset+=count;
 343   }
 344   return(offset);
 345 }
 346 #endif
 347
 348 static StringInfo *GenerateEntropicChaos(RandomInfo *random_info)
 349 {
 350 #define MaxEntropyExtent  64
 351
 352   MagickThreadType
 353     tid;
 354
 355   StringInfo
 356     *chaos,
 357     *entropy;
 358
 359   size_t
 360     nanoseconds,
 361     seconds;
 362
 363   ssize_t
 364     pid;
 365
 366   /*
 367     Initialize random reservoir.
 368   */
 369   entropy=AcquireStringInfo(0);
 370   LockSemaphoreInfo(random_info->semaphore);
 371   chaos=AcquireStringInfo(sizeof(unsigned char *));
 372   SetStringInfoDatum(chaos,(unsigned char *) &entropy);
 373   ConcatenateStringInfo(entropy,chaos);
 374   SetStringInfoDatum(chaos,(unsigned char *) entropy);
 375   ConcatenateStringInfo(entropy,chaos);
 376   pid=(ssize_t) getpid();
 377   SetStringInfoLength(chaos,sizeof(pid));
 378   SetStringInfoDatum(chaos,(unsigned char *) &pid);
 379   ConcatenateStringInfo(entropy,chaos);
 380   tid=GetMagickThreadId();
 381   SetStringInfoLength(chaos,sizeof(tid));
 382   SetStringInfoDatum(chaos,(unsigned char *) &tid);
 383   ConcatenateStringInfo(entropy,chaos);
 384 #if defined(MAGICKCORE_HAVE_GETRUSAGE) && defined(RUSAGE_SELF)
 385   {
 386     struct rusage
 387       usage;
 388
 389     if (getrusage(RUSAGE_SELF,&usage) == 0)
 390       {
 391         SetStringInfoLength(chaos,sizeof(usage));
 392         SetStringInfoDatum(chaos,(unsigned char *) &usage);
 393       }
 394   }
 395 #endif
 396   seconds=time((time_t *) 0);
 397   nanoseconds=0;
 398 #if defined(MAGICKCORE_HAVE_GETTIMEOFDAY)
 399   {
 400     struct timeval
 401       timer;
 402
 403     if (gettimeofday(&timer,(struct timezone *) NULL) == 0)
 404       {
 405         seconds=timer.tv_sec;
 406         nanoseconds=1000UL*timer.tv_usec;
 407       }
 408   }
 409 #endif
 410 #if defined(MAGICKCORE_HAVE_CLOCK_GETTIME) && defined(CLOCK_REALTIME_HR)
 411   {
 412     struct timespec
 413       timer;
 414
 415     if (clock_gettime(CLOCK_REALTIME_HR,&timer) == 0)
 416       {
 417         seconds=timer.tv_sec;
 418         nanoseconds=timer.tv_nsec;
 419       }
 420   }
 421 #endif
 422   SetStringInfoLength(chaos,sizeof(seconds));
 423   SetStringInfoDatum(chaos,(unsigned char *) &seconds);
 424   ConcatenateStringInfo(entropy,chaos);
 425   SetStringInfoLength(chaos,sizeof(nanoseconds));
 426   SetStringInfoDatum(chaos,(unsigned char *) &nanoseconds);
 427   ConcatenateStringInfo(entropy,chaos);
 428   nanoseconds=0;
 429 #if defined(MAGICKCORE_HAVE_CLOCK)
 430   nanoseconds=clock();
 431 #endif
 432 #if defined(MAGICKCORE_HAVE_TIMES)
 433   {
 434     struct tms
 435       timer;
 436
 437     (void) times(&timer);
 438     nanoseconds=timer.tms_utime+timer.tms_stime;
 439   }
 440 #endif
 441   SetStringInfoLength(chaos,sizeof(nanoseconds));
 442   SetStringInfoDatum(chaos,(unsigned char *) &nanoseconds);
 443   ConcatenateStringInfo(entropy,chaos);
 444 #if defined(MAGICKCORE_HAVE_MKSTEMP)
 445   {
 446     char
 447       *filename;
 448
 449     int
 450       file;
 451
 452     filename=ConstantString("magickXXXXXX");
 453     file=mkstemp(filename);
 454 #if defined(__OS2__)
 455     setmode(file,O_BINARY);
 456 #endif
 457     if (file != -1)
 458       (void) close(file);
 459     (void) remove_utf8(filename);
 460     SetStringInfoLength(chaos,strlen(filename));
 461     SetStringInfoDatum(chaos,(unsigned char *) filename);
 462     ConcatenateStringInfo(entropy,chaos);
 463     filename=DestroyString(filename);
 464   }
 465 #endif
 466 #if defined(MAGICKCORE_WINDOWS_SUPPORT)
 467   {
 468     double
 469       seconds;
 470
 471     LARGE_INTEGER
 472       nanoseconds;
 473
 474     MagickBooleanType
 475       status;
 476
 477     /*
 478       Not crytographically strong but better than nothing.
 479     */
 480     seconds=NTElapsedTime()+NTUserTime();
 481     SetStringInfoLength(chaos,sizeof(seconds));
 482     SetStringInfoDatum(chaos,(unsigned char *) &seconds);
 483     ConcatenateStringInfo(entropy,chaos);
 484     if (QueryPerformanceCounter(&nanoseconds) != 0)
 485       {
 486         SetStringInfoLength(chaos,sizeof(nanoseconds));
 487         SetStringInfoDatum(chaos,(unsigned char *) &nanoseconds);
 488         ConcatenateStringInfo(entropy,chaos);
 489       }
 490     /*
 491       Our best hope for true entropy.
 492     */
 493     SetStringInfoLength(chaos,MaxEntropyExtent);
 494     status=NTGatherRandomData(MaxEntropyExtent,GetStringInfoDatum(chaos));
 495     (void) status;
 496     ConcatenateStringInfo(entropy,chaos);
 497   }
 498 #else
 499   {
 500     char
 501       *filename;
 502
 503     int
 504       file;
 505
 506     ssize_t
 507       count;
 508
 509     StringInfo
 510       *device;
 511
 512     /*
 513       Not crytographically strong but better than nothing.
 514     */
 515     if (environ != (char **) NULL)
 516       {
 517         register ssize_t
 518           i;
 519
 520         /*
 521           Squeeze some entropy from the sometimes unpredicatble environment.
 522         */
 523         for (i=0; environ[i] != (char *) NULL; i++)
 524         {
 525           SetStringInfoLength(chaos,strlen(environ[i]));
 526           SetStringInfoDatum(chaos,(unsigned char *) environ[i]);
 527           ConcatenateStringInfo(entropy,chaos);
 528         }
 529       }
 530     filename=AcquireString("/dev/urandom");
 531     device=StringToStringInfo(filename);
 532     device=DestroyStringInfo(device);
 533     file=open_utf8(filename,O_RDONLY | O_BINARY,0);
 534     filename=DestroyString(filename);
 535     if (file != -1)
 536       {
 537         SetStringInfoLength(chaos,MaxEntropyExtent);
 538         count=ReadRandom(file,GetStringInfoDatum(chaos),MaxEntropyExtent);
 539         (void) close(file);
 540         SetStringInfoLength(chaos,(size_t) count);
 541         ConcatenateStringInfo(entropy,chaos);
 542       }
 543     if (gather_true_random != MagickFalse)
 544       {
 545         /*
 546           Our best hope for true entropy.
 547         */
 548         filename=AcquireString("/dev/random");
 549         device=StringToStringInfo(filename);
 550         device=DestroyStringInfo(device);
 551         file=open_utf8(filename,O_RDONLY | O_BINARY,0);
 552         filename=DestroyString(filename);
 553         if (file == -1)
 554           {
 555             filename=AcquireString("/dev/srandom");
 556             device=StringToStringInfo(filename);
 557             device=DestroyStringInfo(device);
 558             file=open_utf8(filename,O_RDONLY | O_BINARY,0);
 559           }
 560         if (file != -1)
 561           {
 562             SetStringInfoLength(chaos,MaxEntropyExtent);
 563             count=ReadRandom(file,GetStringInfoDatum(chaos),MaxEntropyExtent);
 564             (void) close(file);
 565             SetStringInfoLength(chaos,(size_t) count);
 566             ConcatenateStringInfo(entropy,chaos);
 567           }
 568       }
 569   }
 570 #endif
 571   chaos=DestroyStringInfo(chaos);
 572   UnlockSemaphoreInfo(random_info->semaphore);
 573   return(entropy);
 574 }
 575 \f
 576 /*
 577 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 578 %                                                                             %
 579 %                                                                             %
 580 %                                                                             %
 581 %   G e t P s e u d o R a n d o m V a l u e                                   %
 582 %                                                                             %
 583 %                                                                             %
 584 %                                                                             %
 585 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 586 %
 587 %  GetPseudoRandomValue() return a non-negative double-precision floating-point
 588 %  value uniformly distributed over the interval [0.0, 1.0) with a 2 to the
 589 %  128th-1 period.
 590 %
 591 %  The format of the GetPseudoRandomValue method is:
 592 %
 593 %      double GetPseudoRandomValue(RandomInfo *randon_info)
 594 %
 595 %  A description of each parameter follows:
 596 %
 597 %    o random_info: the random info.
 598 %
 599 */
 600 MagickExport double GetPseudoRandomValue(RandomInfo *random_info)
 601 {
 602   register unsigned long
 603     *seed;
 604
 605   unsigned long
 606     alpha;
 607
 608   seed=random_info->seed;
 609   do
 610   {
 611     alpha=(unsigned long) (seed[1] ^ (seed[1] << 11));
 612     seed[1]=seed[2];
 613     seed[2]=seed[3];
 614     seed[3]=seed[0];
 615     seed[0]=(seed[0] ^ (seed[0] >> 19)) ^ (alpha ^ (alpha >> 8));
 616   } while (seed[0] == ~0UL);
 617   return(random_info->normalize*seed[0]);
 618 }
 619 \f
 620 /*
 621 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 622 %                                                                             %
 623 %                                                                             %
 624 %                                                                             %
 625 %   G e t R a n d o m K e y                                                   %
 626 %                                                                             %
 627 %                                                                             %
 628 %                                                                             %
 629 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 630 %
 631 %  GetRandomKey() gets a random key from the reservoir.
 632 %
 633 %  The format of the GetRandomKey method is:
 634 %
 635 %      StringInfo *GetRandomKey(RandomInfo *random_info,const size_t length)
 636 %
 637 %  A description of each parameter follows:
 638 %
 639 %    o random_info: the random info.
 640 %
 641 %    o length: the key length.
 642 %
 643 */
 644 MagickExport StringInfo *GetRandomKey(RandomInfo *random_info,
 645   const size_t length)
 646 {
 647   StringInfo
 648     *key;
 649
 650   assert(random_info != (RandomInfo *) NULL);
 651   key=AcquireStringInfo(length);
 652   SetRandomKey(random_info,length,GetStringInfoDatum(key));
 653   return(key);
 654 }
 655 \f
 656 /*
 657 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 658 %                                                                             %
 659 %                                                                             %
 660 %                                                                             %
 661 %   G e t R a n d o m V a l u e                                               %
 662 %                                                                             %
 663 %                                                                             %
 664 %                                                                             %
 665 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 666 %
 667 %  GetRandomValue() return a non-negative double-precision floating-point
 668 %  value uniformly distributed over the interval [0.0, 1.0) with a 2 to the
 669 %  128th-1 period (not cryptographically strong).
 670 %
 671 %  The format of the GetRandomValue method is:
 672 %
 673 %      double GetRandomValue(void)
 674 %
 675 */
 676 MagickExport double GetRandomValue(RandomInfo *random_info)
 677 {
 678   unsigned long
 679     key,
 680     range;
 681
 682   range=(~0UL);
 683   do
 684   {
 685     SetRandomKey(random_info,sizeof(key),(unsigned char *) &key);
 686   } while (key == range);
 687   return((double) key/range);
 688 }
 689 \f
 690 /*
 691 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 692 %                                                                             %
 693 %                                                                             %
 694 %                                                                             %
 695 +   R a n d o m C o m p o n e n t G e n e s i s                               %
 696 %                                                                             %
 697 %                                                                             %
 698 %                                                                             %
 699 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 700 %
 701 %  RandomComponentGenesis() instantiates the random component.
 702 %
 703 %  The format of the RandomComponentGenesis method is:
 704 %
 705 %      MagickBooleanType RandomComponentGenesis(void)
 706 %
 707 */
 708 MagickPrivate MagickBooleanType RandomComponentGenesis(void)
 709 {
 710   AcquireSemaphoreInfo(&random_semaphore);
 711   return(MagickTrue);
 712 }
 713 \f
 714 /*
 715 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 716 %                                                                             %
 717 %                                                                             %
 718 %                                                                             %
 719 +   R a n d o m C o m p o n e n t T e r m i n u s                             %
 720 %                                                                             %
 721 %                                                                             %
 722 %                                                                             %
 723 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 724 %
 725 %  RandomComponentTerminus() destroys the random component.
 726 %
 727 %  The format of the RandomComponentTerminus method is:
 728 %
 729 %      RandomComponentTerminus(void)
 730 %
 731 */
 732 MagickPrivate void RandomComponentTerminus(void)
 733 {
 734   if (random_semaphore == (SemaphoreInfo *) NULL)
 735     AcquireSemaphoreInfo(&random_semaphore);
 736   DestroySemaphoreInfo(&random_semaphore);
 737 }
 738 \f
 739 /*
 740 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 741 %                                                                             %
 742 %                                                                             %
 743 %                                                                             %
 744 %   S e e d P s e u d o R a n d o m G e n e r a t o r                         %
 745 %                                                                             %
 746 %                                                                             %
 747 %                                                                             %
 748 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 749 %
 750 %  SeedPseudoRandomGenerator() initializes the pseudo-random number generator
 751 %  with a random seed.
 752 %
 753 %  The format of the SeedPseudoRandomGenerator method is:
 754 %
 755 %      void SeedPseudoRandomGenerator(const unsigned long seed)
 756 %
 757 %  A description of each parameter follows:
 758 %
 759 %    o seed: the seed.
 760 %
 761 */
 762 MagickExport void SeedPseudoRandomGenerator(const unsigned long seed)
 763 {
 764   random_seed=seed;
 765 }
 766 \f
 767 /*
 768 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 769 %                                                                             %
 770 %                                                                             %
 771 %                                                                             %
 772 %   S e t R a n d o m K e y                                                   %
 773 %                                                                             %
 774 %                                                                             %
 775 %                                                                             %
 776 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 777 %
 778 %  SetRandomKey() sets a random key from the reservoir.
 779 %
 780 %  The format of the SetRandomKey method is:
 781 %
 782 %      void SetRandomKey(RandomInfo *random_info,const size_t length,
 783 %        unsigned char *key)
 784 %
 785 %  A description of each parameter follows:
 786 %
 787 %    o random_info: the random info.
 788 %
 789 %    o length: the key length.
 790 %
 791 %    o key: the key.
 792 %
 793 */
 794
 795 static inline void IncrementRandomNonce(StringInfo *nonce)
 796 {
 797   register ssize_t
 798     i;
 799
 800   unsigned char
 801     *datum;
 802
 803   datum=GetStringInfoDatum(nonce);
 804   for (i=(ssize_t) (GetStringInfoLength(nonce)-1); i != 0; i--)
 805   {
 806     datum[i]++;
 807     if (datum[i] != 0)
 808       return;
 809   }
 810   ThrowFatalException(RandomFatalError,"SequenceWrapError");
 811 }
 812
 813 MagickExport void SetRandomKey(RandomInfo *random_info,const size_t length,
 814   unsigned char *key)
 815 {
 816   register size_t
 817     i;
 818
 819   register unsigned char
 820     *p;
 821
 822   SignatureInfo
 823     *signature_info;
 824
 825   unsigned char
 826     *datum;
 827
 828   assert(random_info != (RandomInfo *) NULL);
 829   if (length == 0)
 830     return;
 831   LockSemaphoreInfo(random_info->semaphore);
 832   signature_info=random_info->signature_info;
 833   datum=GetStringInfoDatum(random_info->reservoir);
 834   i=length;
 835   for (p=key; (i != 0) && (random_info->i != 0); i--)
 836   {
 837     *p++=datum[random_info->i];
 838     random_info->i++;
 839     if (random_info->i == GetSignatureDigestsize(signature_info))
 840       random_info->i=0;
 841   }
 842   while (i >= GetSignatureDigestsize(signature_info))
 843   {
 844     InitializeSignature(signature_info);
 845     UpdateSignature(signature_info,random_info->nonce);
 846     FinalizeSignature(signature_info);
 847     IncrementRandomNonce(random_info->nonce);
 848     (void) CopyMagickMemory(p,GetStringInfoDatum(GetSignatureDigest(
 849       signature_info)),GetSignatureDigestsize(signature_info));
 850     p+=GetSignatureDigestsize(signature_info);
 851     i-=GetSignatureDigestsize(signature_info);
 852   }
 853   if (i != 0)
 854     {
 855       InitializeSignature(signature_info);
 856       UpdateSignature(signature_info,random_info->nonce);
 857       FinalizeSignature(signature_info);
 858       IncrementRandomNonce(random_info->nonce);
 859       SetStringInfo(random_info->reservoir,GetSignatureDigest(signature_info));
 860       random_info->i=i;
 861       datum=GetStringInfoDatum(random_info->reservoir);
 862       while (i-- != 0)
 863         p[i]=datum[i];
 864     }
 865   UnlockSemaphoreInfo(random_info->semaphore);
 866 }
 867 \f
 868 /*
 869 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 870 %                                                                             %
 871 %                                                                             %
 872 %                                                                             %
 873 %   S e t R a n d o m T r u e R a n d o m                                     %
 874 %                                                                             %
 875 %                                                                             %
 876 %                                                                             %
 877 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 878 %
 879 %  SetRandomTrueRandom() declares your intentions to use true random numbers.
 880 %  True random numbers are encouraged but may not always be practical because
 881 %  your application may block while entropy is gathered from your environment.
 882 %
 883 %  The format of the SetRandomTrueRandom method is:
 884 %
 885 %      void SetRandomTrueRandom(const MagickBooleanType true_random)
 886 %
 887 %  A description of each parameter follows:
 888 %
 889 %    o true_random: declare your intentions to use true-random number.
 890 %
 891 */
 892 MagickExport void SetRandomTrueRandom(const MagickBooleanType true_random)
 893 {
 894   gather_true_random=true_random;
 895 }