root/magick/signature.c

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DEFINITIONS

This source file includes following definitions.
  1. AcquireSignatureInfo
  2. DestroySignatureInfo
  3. FinalizeSignature
  4. GetSignatureBlocksize
  5. GetSignatureDigest
  6. GetSignatureDigestsize
  7. InitializeSignature
  8. SetSignatureDigest
  9. SignatureImage
  10. Ch
  11. Maj
  12. Trunc32
  13. RotateRight
  14. TransformSignature
  15. UpdateSignature

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%        SSSSS  IIIII   GGGG  N   N   AAA   TTTTT  U   U  RRRR   EEEEE        %
%        SS       I    G      NN  N  A   A    T    U   U  R   R  E            %
%         SSS     I    G  GG  N N N  AAAAA    T    U   U  RRRR   EEE          %
%           SS    I    G   G  N  NN  A   A    T    U   U  R R    E            %
%        SSSSS  IIIII   GGG   N   N  A   A    T     UUU   R  R   EEEEE        %
%                                                                             %
%                                                                             %
%         MagickCore Methods to Compute a Message Digest for an Image         %
%                                                                             %
%                             Software Design                                 %
%                               John Cristy                                   %
%                              December 1992                                  %
%                                                                             %
%                                                                             %
%  Copyright 1999-2013 ImageMagick Studio LLC, a non-profit organization      %
%  dedicated to making software imaging solutions freely available.           %
%                                                                             %
%  You may not use this file except in compliance with the License.  You may  %
%  obtain a copy of the License at                                            %
%                                                                             %
%    http://www.imagemagick.org/script/license.php                            %
%                                                                             %
%  Unless required by applicable law or agreed to in writing, software        %
%  distributed under the License is distributed on an "AS IS" BASIS,          %
%  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
%  See the License for the specific language governing permissions and        %
%  limitations under the License.                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%
%
*/

/*
  Include declarations.
*/
#include "magick/studio.h"
#include "magick/cache.h"
#include "magick/exception.h"
#include "magick/exception-private.h"
#include "magick/property.h"
#include "magick/image.h"
#include "magick/memory_.h"
#include "magick/quantum.h"
#include "magick/quantum-private.h"
#include "magick/signature.h"
#include "magick/signature-private.h"
#include "magick/string_.h"
/*
  Define declarations.
*/
#define SignatureBlocksize  64
#define SignatureDigestsize  32

/*
  Typedef declarations.
*/
struct _SignatureInfo
{
  unsigned int
    digestsize,
    blocksize;

  StringInfo
    *digest,
    *message;

  unsigned int
    *accumulator,
    low_order,
    high_order;

  size_t
    offset;

  MagickBooleanType
    lsb_first;

  ssize_t
    timestamp;

  size_t
    signature;
};

/*
  Forward declarations.
*/
static void
  TransformSignature(SignatureInfo *);

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   A c q u i r e S i g n a t u r e I n f o                                   %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  AcquireSignatureInfo() allocate the SignatureInfo structure.
%
%  The format of the AcquireSignatureInfo method is:
%
%      SignatureInfo *AcquireSignatureInfo(void)
%
*/
MagickExport SignatureInfo *AcquireSignatureInfo(void)
{
  SignatureInfo
    *signature_info;

  unsigned int
    lsb_first;

  signature_info=(SignatureInfo *) AcquireMagickMemory(sizeof(*signature_info));
  if (signature_info == (SignatureInfo *) NULL)
    ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
  (void) ResetMagickMemory(signature_info,0,sizeof(*signature_info));
  signature_info->digestsize=SignatureDigestsize;
  signature_info->blocksize=SignatureBlocksize;
  signature_info->digest=AcquireStringInfo(SignatureDigestsize);
  signature_info->message=AcquireStringInfo(SignatureBlocksize);
  signature_info->accumulator=(unsigned int *) AcquireQuantumMemory(
    SignatureBlocksize,sizeof(*signature_info->accumulator));
  if (signature_info->accumulator == (unsigned int *) NULL)
    ThrowFatalException(ResourceLimitFatalError,"MemoryAllocationFailed");
  lsb_first=1;
  signature_info->lsb_first=(int) (*(char *) &lsb_first) == 1 ? MagickTrue :
    MagickFalse;
  signature_info->timestamp=(ssize_t) time(0);
  signature_info->signature=MagickSignature;
  InitializeSignature(signature_info);
  return(signature_info);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   D e s t r o y S i g n a t u r e I n f o                                   %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  DestroySignatureInfo() zeros memory associated with the SignatureInfo
%  structure.
%
%  The format of the DestroySignatureInfo method is:
%
%      SignatureInfo *DestroySignatureInfo(SignatureInfo *signature_info)
%
%  A description of each parameter follows:
%
%    o signature_info: the cipher signature_info.
%
*/
MagickExport SignatureInfo *DestroySignatureInfo(SignatureInfo *signature_info)
{
  (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
  assert(signature_info != (SignatureInfo *) NULL);
  assert(signature_info->signature == MagickSignature);
  if (signature_info->accumulator != (unsigned int *) NULL)
    signature_info->accumulator=(unsigned int *) RelinquishMagickMemory(
      signature_info->accumulator);
  if (signature_info->message != (StringInfo *) NULL)
    signature_info->message=DestroyStringInfo(signature_info->message);
  if (signature_info->digest != (StringInfo *) NULL)
    signature_info->digest=DestroyStringInfo(signature_info->digest);
  signature_info->signature=(~MagickSignature);
  signature_info=(SignatureInfo *) RelinquishMagickMemory(signature_info);
  return(signature_info);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   F i n a l i z e S i g n a t u r e                                         %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  FinalizeSignature() finalizes the Signature message accumulator computation.
%
%  The format of the FinalizeSignature method is:
%
%      FinalizeSignature(SignatureInfo *signature_info)
%
%  A description of each parameter follows:
%
%    o signature_info: the address of a structure of type SignatureInfo.
%
*/
MagickExport void FinalizeSignature(SignatureInfo *signature_info)
{
  register ssize_t
    i;

  register unsigned char
    *q;

  register unsigned int
    *p;

  unsigned char
    *datum;

  unsigned int
    count,
    high_order,
    low_order;

  /*
    Add padding and return the message accumulator.
  */
  (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
  assert(signature_info != (SignatureInfo *) NULL);
  assert(signature_info->signature == MagickSignature);
  low_order=signature_info->low_order;
  high_order=signature_info->high_order;
  count=((low_order >> 3) & 0x3f);
  datum=GetStringInfoDatum(signature_info->message);
  datum[count++]=(unsigned char) 0x80;
  if (count <= (unsigned int) (GetStringInfoLength(signature_info->message)-8))
    (void) ResetMagickMemory(datum+count,0,GetStringInfoLength(
      signature_info->message)-8-count);
  else
    {
      (void) ResetMagickMemory(datum+count,0,GetStringInfoLength(
        signature_info->message)-count);
      TransformSignature(signature_info);
      (void) ResetMagickMemory(datum,0,GetStringInfoLength(
        signature_info->message)-8);
    }
  datum[56]=(unsigned char) (high_order >> 24);
  datum[57]=(unsigned char) (high_order >> 16);
  datum[58]=(unsigned char) (high_order >> 8);
  datum[59]=(unsigned char) high_order;
  datum[60]=(unsigned char) (low_order >> 24);
  datum[61]=(unsigned char) (low_order >> 16);
  datum[62]=(unsigned char) (low_order >> 8);
  datum[63]=(unsigned char) low_order;
  TransformSignature(signature_info);
  p=signature_info->accumulator;
  q=GetStringInfoDatum(signature_info->digest);
  for (i=0; i < (SignatureDigestsize/4); i++)
  {
    *q++=(unsigned char) ((*p >> 24) & 0xff);
    *q++=(unsigned char) ((*p >> 16) & 0xff);
    *q++=(unsigned char) ((*p >> 8) & 0xff);
    *q++=(unsigned char) (*p & 0xff);
    p++;
  }
  /*
    Reset working registers.
  */
  count=0;
  high_order=0;
  low_order=0;
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   G e t S i g n a t u r e B l o c k s i z e                                 %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  GetSignatureBlocksize() returns the Signature blocksize.
%
%  The format of the GetSignatureBlocksize method is:
%
%      unsigned int *GetSignatureBlocksize(const SignatureInfo *signature_info)
%
%  A description of each parameter follows:
%
%    o signature_info: the signature info.
%
*/
MagickExport unsigned int GetSignatureBlocksize(
  const SignatureInfo *signature_info)
{
  (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
  assert(signature_info != (SignatureInfo *) NULL);
  assert(signature_info->signature == MagickSignature);
  return(signature_info->blocksize);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   G e t S i g n a t u r e D i g e s t                                       %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  GetSignatureDigest() returns the signature digest.
%
%  The format of the GetSignatureDigest method is:
%
%      const StringInfo *GetSignatureDigest(const SignatureInfo *signature_info)
%
%  A description of each parameter follows:
%
%    o signature_info: the signature info.
%
*/
MagickExport const StringInfo *GetSignatureDigest(
  const SignatureInfo *signature_info)
{
  (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
  assert(signature_info != (SignatureInfo *) NULL);
  assert(signature_info->signature == MagickSignature);
  return(signature_info->digest);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   G e t S i g n a t u r e D i g e s t s i z e                               %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  GetSignatureDigestsize() returns the Signature digest size.
%
%  The format of the GetSignatureDigestsize method is:
%
%      unsigned int *GetSignatureDigestsize(const SignatureInfo *signature_info)
%
%  A description of each parameter follows:
%
%    o signature_info: the signature info.
%
*/
MagickExport unsigned int GetSignatureDigestsize(
  const SignatureInfo *signature_info)
{
  (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
  assert(signature_info != (SignatureInfo *) NULL);
  assert(signature_info->signature == MagickSignature);
  return(signature_info->digestsize);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   I n i t i a l i z e S i g n a t u r e                                     %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  InitializeSignature() initializes the Signature accumulator.
%
%  The format of the DestroySignatureInfo method is:
%
%      void InitializeSignatureInfo(SignatureInfo *signature_info)
%
%  A description of each parameter follows:
%
%    o signature_info: the cipher signature_info.
%
*/
MagickExport void InitializeSignature(SignatureInfo *signature_info)
{
  (void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
  assert(signature_info != (SignatureInfo *) NULL);
  assert(signature_info->signature == MagickSignature);
  signature_info->accumulator[0]=0x6a09e667U;
  signature_info->accumulator[1]=0xbb67ae85U;
  signature_info->accumulator[2]=0x3c6ef372U;
  signature_info->accumulator[3]=0xa54ff53aU;
  signature_info->accumulator[4]=0x510e527fU;
  signature_info->accumulator[5]=0x9b05688cU;
  signature_info->accumulator[6]=0x1f83d9abU;
  signature_info->accumulator[7]=0x5be0cd19U;
  signature_info->low_order=0;
  signature_info->high_order=0;
  signature_info->offset=0;
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   S e t S i g n a t u r e D i g e s t                                       %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  SetSignatureDigest() set the signature digest.
%
%  The format of the SetSignatureDigest method is:
%
%      SetSignatureDigest(SignatureInfo *signature_info,
%        const StringInfo *digest)
%
%  A description of each parameter follows:
%
%    o signature_info: the signature info.
%
%    o digest: the digest.
%
*/
MagickExport void SetSignatureDigest(SignatureInfo *signature_info,
  const StringInfo *digest)
{
  /*
    Set the signature accumulator.
  */
  assert(signature_info != (SignatureInfo *) NULL);
  assert(signature_info->signature == MagickSignature);
  SetStringInfo(signature_info->digest,digest);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
%   S i g n a t u r e I m a g e                                               %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  SignatureImage() computes a message digest from an image pixel stream with
%  an implementation of the NIST SHA-256 Message Digest algorithm.  This
%  signature uniquely identifies the image and is convenient for determining
%  if an image has been modified or whether two images are identical.
%
%  The format of the SignatureImage method is:
%
%      MagickBooleanType SignatureImage(Image *image)
%
%  A description of each parameter follows:
%
%    o image: the image.
%
*/
MagickExport MagickBooleanType SignatureImage(Image *image)
{
  CacheView
    *image_view;

  char
    *hex_signature;

  ExceptionInfo
    *exception;

  QuantumInfo
    *quantum_info;

  QuantumType
    quantum_type;

  register const PixelPacket
    *p;

  SignatureInfo
    *signature_info;

  size_t
    length;

  ssize_t
    y;

  StringInfo
    *signature;

  unsigned char
    *pixels;

  /*
    Compute image digital signature.
  */
  assert(image != (Image *) NULL);
  assert(image->signature == MagickSignature);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
  quantum_info=AcquireQuantumInfo((const ImageInfo *) NULL,image);
  if (quantum_info == (QuantumInfo *) NULL)
    ThrowBinaryException(ResourceLimitError,"MemoryAllocationFailed",
      image->filename);
  quantum_type=RGBQuantum;
  if (image->matte != MagickFalse)
    quantum_type=RGBAQuantum;
  if (image->colorspace == CMYKColorspace)
    {
      quantum_type=CMYKQuantum;
      if (image->matte != MagickFalse)
        quantum_type=CMYKAQuantum;
    }
  signature_info=AcquireSignatureInfo();
  signature=AcquireStringInfo(quantum_info->extent);
  pixels=GetQuantumPixels(quantum_info);
  exception=(&image->exception);
  image_view=AcquireVirtualCacheView(image,exception);
  for (y=0; y < (ssize_t) image->rows; y++)
  {
    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
    if (p == (const PixelPacket *) NULL)
      break;
    length=ExportQuantumPixels(image,image_view,quantum_info,quantum_type,
      pixels,&image->exception);
    SetStringInfoLength(signature,length);
    SetStringInfoDatum(signature,pixels);
    UpdateSignature(signature_info,signature);
  }
  image_view=DestroyCacheView(image_view);
  quantum_info=DestroyQuantumInfo(quantum_info);
  FinalizeSignature(signature_info);
  hex_signature=StringInfoToHexString(GetSignatureDigest(signature_info));
  (void) DeleteImageProperty(image,"signature");
  (void) SetImageProperty(image,"signature",hex_signature);
  /*
    Free resources.
  */
  hex_signature=DestroyString(hex_signature);
  signature=DestroyStringInfo(signature);
  signature_info=DestroySignatureInfo(signature_info);
  return(MagickTrue);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   T r a n s f o r m S i g n a t u r e                                       %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  TransformSignature() transforms the Signature message accumulator.
%
%  The format of the TransformSignature method is:
%
%      TransformSignature(SignatureInfo *signature_info)
%
%  A description of each parameter follows:
%
%    o signature_info: the address of a structure of type SignatureInfo.
%
*/

static inline unsigned int Ch(unsigned int x,unsigned int y,unsigned int z)
{
  return((x & y) ^ (~x & z));
}

static inline unsigned int Maj(unsigned int x,unsigned int y,unsigned int z)
{
  return((x & y) ^ (x & z) ^ (y & z));
}

static inline unsigned int Trunc32(unsigned int x)
{
  return((unsigned int) (x & 0xffffffffU));
}

static unsigned int RotateRight(unsigned int x,unsigned int n)
{
  return(Trunc32((x >> n) | (x << (32-n))));
}

static void TransformSignature(SignatureInfo *signature_info)
{
#define Sigma0(x)  (RotateRight(x,7) ^ RotateRight(x,18) ^ Trunc32((x) >> 3))
#define Sigma1(x)  (RotateRight(x,17) ^ RotateRight(x,19) ^ Trunc32((x) >> 10))
#define Suma0(x)  (RotateRight(x,2) ^ RotateRight(x,13) ^ RotateRight(x,22))
#define Suma1(x)  (RotateRight(x,6) ^ RotateRight(x,11) ^ RotateRight(x,25))

  register ssize_t
    i;

  register unsigned char
    *p;

  ssize_t
    j;

  static unsigned int
    K[64] =
    {
      0x428a2f98U, 0x71374491U, 0xb5c0fbcfU, 0xe9b5dba5U, 0x3956c25bU,
      0x59f111f1U, 0x923f82a4U, 0xab1c5ed5U, 0xd807aa98U, 0x12835b01U,
      0x243185beU, 0x550c7dc3U, 0x72be5d74U, 0x80deb1feU, 0x9bdc06a7U,
      0xc19bf174U, 0xe49b69c1U, 0xefbe4786U, 0x0fc19dc6U, 0x240ca1ccU,
      0x2de92c6fU, 0x4a7484aaU, 0x5cb0a9dcU, 0x76f988daU, 0x983e5152U,
      0xa831c66dU, 0xb00327c8U, 0xbf597fc7U, 0xc6e00bf3U, 0xd5a79147U,
      0x06ca6351U, 0x14292967U, 0x27b70a85U, 0x2e1b2138U, 0x4d2c6dfcU,
      0x53380d13U, 0x650a7354U, 0x766a0abbU, 0x81c2c92eU, 0x92722c85U,
      0xa2bfe8a1U, 0xa81a664bU, 0xc24b8b70U, 0xc76c51a3U, 0xd192e819U,
      0xd6990624U, 0xf40e3585U, 0x106aa070U, 0x19a4c116U, 0x1e376c08U,
      0x2748774cU, 0x34b0bcb5U, 0x391c0cb3U, 0x4ed8aa4aU, 0x5b9cca4fU,
      0x682e6ff3U, 0x748f82eeU, 0x78a5636fU, 0x84c87814U, 0x8cc70208U,
      0x90befffaU, 0xa4506cebU, 0xbef9a3f7U, 0xc67178f2U
    };  /* 32-bit fractional part of the cube root of the first 64 primes */

  unsigned int
    A,
    B,
    C,
    D,
    E,
    F,
    G,
    H,
    shift,
    T,
    T1,
    T2,
    W[64];

  shift=32;
  p=GetStringInfoDatum(signature_info->message);
  if (signature_info->lsb_first == MagickFalse)
    {
      if (sizeof(unsigned int) <= 4)
        for (i=0; i < 16; i++)
        {
          T=(*((unsigned int *) p));
          p+=4;
          W[i]=Trunc32(T);
        }
      else
        for (i=0; i < 16; i+=2)
        {
          T=(*((unsigned int *) p));
          p+=8;
          W[i]=Trunc32(T >> shift);
          W[i+1]=Trunc32(T);
        }
    }
  else
    if (sizeof(unsigned int) <= 4)
      for (i=0; i < 16; i++)
      {
        T=(*((unsigned int *) p));
        p+=4;
        W[i]=((T << 24) & 0xff000000) | ((T << 8) & 0x00ff0000) |
          ((T >> 8) & 0x0000ff00) | ((T >> 24) & 0x000000ff);
      }
    else
      for (i=0; i < 16; i+=2)
      {
        T=(*((unsigned int *) p));
        p+=8;
        W[i]=((T << 24) & 0xff000000) | ((T << 8) & 0x00ff0000) |
          ((T >> 8) & 0x0000ff00) | ((T >> 24) & 0x000000ff);
        T>>=shift;
        W[i+1]=((T << 24) & 0xff000000) | ((T << 8) & 0x00ff0000) |
          ((T >> 8) & 0x0000ff00) | ((T >> 24) & 0x000000ff);
      }
  /*
    Copy accumulator to registers.
  */
  A=signature_info->accumulator[0];
  B=signature_info->accumulator[1];
  C=signature_info->accumulator[2];
  D=signature_info->accumulator[3];
  E=signature_info->accumulator[4];
  F=signature_info->accumulator[5];
  G=signature_info->accumulator[6];
  H=signature_info->accumulator[7];
  for (i=16; i < 64; i++)
    W[i]=Trunc32(Sigma1(W[i-2])+W[i-7]+Sigma0(W[i-15])+W[i-16]);
  for (j=0; j < 64; j++)
  {
    T1=Trunc32(H+Suma1(E)+Ch(E,F,G)+K[j]+W[j]);
    T2=Trunc32(Suma0(A)+Maj(A,B,C));
    H=G;
    G=F;
    F=E;
    E=Trunc32(D+T1);
    D=C;
    C=B;
    B=A;
    A=Trunc32(T1+T2);
  }
  /*
    Add registers back to accumulator.
  */
  signature_info->accumulator[0]=Trunc32(signature_info->accumulator[0]+A);
  signature_info->accumulator[1]=Trunc32(signature_info->accumulator[1]+B);
  signature_info->accumulator[2]=Trunc32(signature_info->accumulator[2]+C);
  signature_info->accumulator[3]=Trunc32(signature_info->accumulator[3]+D);
  signature_info->accumulator[4]=Trunc32(signature_info->accumulator[4]+E);
  signature_info->accumulator[5]=Trunc32(signature_info->accumulator[5]+F);
  signature_info->accumulator[6]=Trunc32(signature_info->accumulator[6]+G);
  signature_info->accumulator[7]=Trunc32(signature_info->accumulator[7]+H);
  /*
    Reset working registers.
  */
  A=0;
  B=0;
  C=0;
  D=0;
  E=0;
  F=0;
  G=0;
  H=0;
  T=0;
  T1=0;
  T2=0;
  (void) ResetMagickMemory(W,0,sizeof(W));
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
%                                                                             %
+   U p d a t e S i g n a t u r e                                             %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  UpdateSignature() updates the Signature message accumulator.
%
%  The format of the UpdateSignature method is:
%
%      UpdateSignature(SignatureInfo *signature_info,const StringInfo *message)
%
%  A description of each parameter follows:
%
%    o signature_info: the address of a structure of type SignatureInfo.
%
%    o message: the message.
%
*/
MagickExport void UpdateSignature(SignatureInfo *signature_info,
  const StringInfo *message)
{
  register size_t
    i;

  register unsigned char
    *p;

  size_t
    n;

  unsigned int
    length;

  /*
    Update the Signature accumulator.
  */
  assert(signature_info != (SignatureInfo *) NULL);
  assert(signature_info->signature == MagickSignature);
  n=GetStringInfoLength(message);
  length=Trunc32((unsigned int) (signature_info->low_order+(n << 3)));
  if (length < signature_info->low_order)
    signature_info->high_order++;
  signature_info->low_order=length;
  signature_info->high_order+=(unsigned int) (n >> 29);
  p=GetStringInfoDatum(message);
  if (signature_info->offset != 0)
    {
      i=GetStringInfoLength(signature_info->message)-signature_info->offset;
      if (i > n)
        i=n;
      (void) CopyMagickMemory(GetStringInfoDatum(signature_info->message)+
        signature_info->offset,p,i);
      n-=i;
      p+=i;
      signature_info->offset+=i;
      if (signature_info->offset !=
          GetStringInfoLength(signature_info->message))
        return;
      TransformSignature(signature_info);
    }
  while (n >= GetStringInfoLength(signature_info->message))
  {
    SetStringInfoDatum(signature_info->message,p);
    p+=GetStringInfoLength(signature_info->message);
    n-=GetStringInfoLength(signature_info->message);
    TransformSignature(signature_info);
  }
  (void) CopyMagickMemory(GetStringInfoDatum(signature_info->message),p,n);
  signature_info->offset=n;
  /*
    Reset working registers.
  */
  i=0;
  n=0;
  length=0;
}

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