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signature.c
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% 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 %
% Cristy %
% December 1992 %
% %
% %
% Copyright @ 1999 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 %
% %
% https://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 "MagickCore/studio.h"
#include "MagickCore/cache.h"
#include "MagickCore/exception.h"
#include "MagickCore/exception-private.h"
#include "MagickCore/property.h"
#include "MagickCore/image.h"
#include "MagickCore/memory_.h"
#include "MagickCore/memory-private.h"
#include "MagickCore/pixel-accessor.h"
#include "MagickCore/quantum.h"
#include "MagickCore/quantum-private.h"
#include "MagickCore/signature.h"
#include "MagickCore/signature-private.h"
#include "MagickCore/string_.h"
#include "MagickCore/timer-private.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
extent;
MagickBooleanType
lsb_first;
time_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)
%
*/
MagickPrivate SignatureInfo *AcquireSignatureInfo(void)
{
SignatureInfo
*signature_info;
unsigned long
lsb_first;
signature_info=(SignatureInfo *) AcquireCriticalMemory(
sizeof(*signature_info));
(void) memset(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");
(void) memset(signature_info->accumulator,0,SignatureBlocksize*
sizeof(*signature_info->accumulator));
lsb_first=1;
signature_info->lsb_first=(int) (*(char *) &lsb_first) == 1 ? MagickTrue :
MagickFalse;
signature_info->timestamp=GetMagickTime();
signature_info->signature=MagickCoreSignature;
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.
%
*/
MagickPrivate SignatureInfo *DestroySignatureInfo(SignatureInfo *signature_info)
{
assert(signature_info != (SignatureInfo *) NULL);
assert(signature_info->signature == MagickCoreSignature);
if (IsEventLogging() != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
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=(~MagickCoreSignature);
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.
%
*/
MagickPrivate void FinalizeSignature(SignatureInfo *signature_info)
{
ssize_t
i;
unsigned char
*q;
unsigned int
*p;
size_t
extent;
unsigned char
*datum;
unsigned int
high_order,
low_order;
/*
Add padding and return the message accumulator.
*/
assert(signature_info != (SignatureInfo *) NULL);
assert(signature_info->signature == MagickCoreSignature);
if (IsEventLogging() != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
low_order=signature_info->low_order;
high_order=signature_info->high_order;
extent=((low_order >> 3) & 0x3f);
datum=GetStringInfoDatum(signature_info->message);
datum[extent++]=(unsigned char) 0x80;
if (extent <= (unsigned int) (GetStringInfoLength(signature_info->message)-8))
(void) memset(datum+extent,0,GetStringInfoLength(
signature_info->message)-8-extent);
else
{
(void) memset(datum+extent,0,GetStringInfoLength(
signature_info->message)-extent);
TransformSignature(signature_info);
(void) memset(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++;
}
}
␌
/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% %
% %
+ 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.
%
*/
MagickPrivate unsigned int GetSignatureBlocksize(
const SignatureInfo *signature_info)
{
assert(signature_info != (SignatureInfo *) NULL);
assert(signature_info->signature == MagickCoreSignature);
if (IsEventLogging() != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
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.
%
*/
MagickPrivate const StringInfo *GetSignatureDigest(
const SignatureInfo *signature_info)
{
assert(signature_info != (SignatureInfo *) NULL);
assert(signature_info->signature == MagickCoreSignature);
if (IsEventLogging() != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
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.
%
*/
MagickPrivate unsigned int GetSignatureDigestsize(
const SignatureInfo *signature_info)
{
assert(signature_info != (SignatureInfo *) NULL);
assert(signature_info->signature == MagickCoreSignature);
if (IsEventLogging() != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
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.
%
*/
MagickPrivate void InitializeSignature(SignatureInfo *signature_info)
{
assert(signature_info != (SignatureInfo *) NULL);
assert(signature_info->signature == MagickCoreSignature);
if (IsEventLogging() != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"...");
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->extent=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.
%
*/
MagickPrivate void SetSignatureDigest(SignatureInfo *signature_info,
const StringInfo *digest)
{
/*
Set the signature accumulator.
*/
assert(signature_info != (SignatureInfo *) NULL);
assert(signature_info->signature == MagickCoreSignature);
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,ExceptionInfo *exception)
%
% A description of each parameter follows:
%
% o image: the image.
%
% o exception: return any errors or warnings in this structure.
%
*/
MagickExport MagickBooleanType SignatureImage(Image *image,
ExceptionInfo *exception)
{
CacheView
*image_view;
char
*hex_signature;
float
pixel;
const Quantum
*p;
SignatureInfo
*signature_info;
ssize_t
y;
StringInfo
*signature;
unsigned char
*pixels;
/*
Compute image digital signature.
*/
assert(image != (Image *) NULL);
assert(image->signature == MagickCoreSignature);
if (IsEventLogging() != MagickFalse)
(void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
signature_info=AcquireSignatureInfo();
signature=AcquireStringInfo(GetPixelChannels(image)*image->columns*
sizeof(pixel));
image_view=AcquireVirtualCacheView(image,exception);
for (y=0; y < (ssize_t) image->rows; y++)
{
ssize_t
x;
unsigned char
*q;
p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
if (p == (const Quantum *) NULL)
break;
SetStringInfoLength(signature,GetPixelChannels(image)*image->columns*
sizeof(pixel));
pixels=GetStringInfoDatum(signature);
q=pixels;
for (x=0; x < (ssize_t) image->columns; x++)
{
ssize_t
i;
if (GetPixelReadMask(image,p) <= (QuantumRange/2))
{
p+=(ptrdiff_t) GetPixelChannels(image);
continue;
}
for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
{
ssize_t
j;
PixelChannel channel = GetPixelChannelChannel(image,i);
PixelTrait traits = GetPixelChannelTraits(image,channel);
if ((traits & UpdatePixelTrait) == 0)
continue;
pixel=(float) (QuantumScale*(double) p[i]);
if (signature_info->lsb_first == MagickFalse)
for (j=(ssize_t) sizeof(pixel)-1; j >= 0; j--)
*q++=(unsigned char) ((unsigned char *) &pixel)[j];
else
for (j=0; j < (ssize_t) sizeof(pixel); j++)
*q++=(unsigned char) ((unsigned char *) &pixel)[j];
}
p+=(ptrdiff_t) GetPixelChannels(image);
}
SetStringInfoLength(signature,(size_t) (q-pixels));
UpdateSignature(signature_info,signature);
}
image_view=DestroyCacheView(image_view);
FinalizeSignature(signature_info);
hex_signature=StringInfoToHexString(GetSignatureDigest(signature_info));
(void) DeleteImageProperty(image,"signature");
(void) SetImageProperty(image,"signature",hex_signature,exception);
/*
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 void TransformSignature(SignatureInfo *signature_info)
{
#define Ch(x,y,z) (((x) & (y)) ^ (~(x) & (z)))
#define Maj(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
#define RotateRight(x,n) (Trunc32(((x) >> n) | ((x) << (32-n))))
#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))
#define Trunc32(x) ((unsigned int) ((x) & 0xffffffffU))
ssize_t
i;
unsigned char
*p;
ssize_t
j;
static const 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 = 0,
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)
{
DisableMSCWarning(4127)
if (sizeof(unsigned int) <= 4)
RestoreMSCWarning
for (i=0; i < 16; i++)
{
T=(*((unsigned int *) p));
p+=(ptrdiff_t) 4;
W[i]=Trunc32(T);
}
else
for (i=0; i < 16; i+=2)
{
T=(*((unsigned int *) p));
p+=(ptrdiff_t) 8;
W[i]=Trunc32(T >> shift);
W[i+1]=Trunc32(T);
}
}
else
DisableMSCWarning(4127)
if (sizeof(unsigned int) <= 4)
RestoreMSCWarning
for (i=0; i < 16; i++)
{
T=(*((unsigned int *) p));
p+=(ptrdiff_t) 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+=(ptrdiff_t) 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.
%
*/
MagickPrivate void UpdateSignature(SignatureInfo *signature_info,
const StringInfo *message)
{
size_t
i;
unsigned char
*p;
size_t
n;
unsigned int
length;
/*
Update the Signature accumulator.
*/
assert(signature_info != (SignatureInfo *) NULL);
assert(signature_info->signature == MagickCoreSignature);
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->extent != 0)
{
i=GetStringInfoLength(signature_info->message)-signature_info->extent;
if (i > n)
i=n;
(void) memcpy(GetStringInfoDatum(signature_info->message)+
signature_info->extent,p,i);
n-=i;
p+=(ptrdiff_t) i;
signature_info->extent+=i;
if (signature_info->extent != GetStringInfoLength(signature_info->message))
return;
TransformSignature(signature_info);
}
while (n >= GetStringInfoLength(signature_info->message))
{
SetStringInfoDatum(signature_info->message,p);
p+=(ptrdiff_t) GetStringInfoLength(signature_info->message);
n-=GetStringInfoLength(signature_info->message);
TransformSignature(signature_info);
}
(void) memcpy(GetStringInfoDatum(signature_info->message),p,n);
signature_info->extent=n;
}
_CacheView
Definition cache-view.c:66
_ExceptionInfo
Definition exception.h:102
_Image
Definition image.h:132
_SignatureInfo
Definition signature.c:67
_StringInfo
Definition string_.h:28