SHA1MessageDigest

Computes SHA-1 digest value of the input message.

Syntax

IppStatus ippsSHA1MessageDigest(const Ipp8u *pSrcMesg, int mesglen, Ipp8u *pMD);

Parameters

pSrcMesg	Pointer to the input message.
mesglen	Message length in octets.
pMD	Pointer to the resultant digest.

Description

This function is declared in the ippcp.h file. The function uses the selected hash algorithm to compute the digest value of the entire (non-streaming) input message.

Return Values

ippStsNoErr	Indicates no error. Any other value indicates an error or warning.
ippStsNullPtrErr	Indicates an error condition if any of the specified pointers is NULL.
ippStsLengthErr	Indicates an error condition if the input data stream length is less than zero.

SHA1 Digest of a Message

    //    Compute two SHA1 digests of a message:

    //    1-st will correspond of 1/2 message

    //    2-nd will correspond of whole message

void SHA1_sample(void){

   // get size of the SHA1 context

   int ctxSize;

   ippsSHA1GetSize(&ctxSize);

   // allocate the SHA1 context

   IppsSHA1State* pCtx = (IppsSHA1State*)( new Ipp8u [ctxSize] );

   // and initialize the context

   ippsSHA1Init(pCtx);

   // define a message

   Ipp8u msg[] = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq";

   int n;

   // update digest using a piece of message

   for(n=0; n<(sizeof(msg)-1)/2; n++)

      ippsSHA1Update(msg+n, 1, pCtx);

// clone the SHA1 context

   IppsSHA1State* pCtx2 = (IppsSHA1State*)( new Ipp8u [ctxSize] );

   ippsSHA1Init(pCtx2);

   ippsSHA1Duplicate(pCtx, pCtx2);

 // finalize and extract digest of a half message

   Ipp8u digest[20];

   ippsSHA1Final(digest, pCtx);

   // update digest using the SHA1 clone context

   ippsSHA1Update(msg+n, sizeof(msg)-1-n, pCtx2);

   // finalize and extract digest of a whole message

   Ipp8u digest2[20];

   ippsSHA1Final(digest2, pCtx2);

   delete [] (Ipp8u*)pCtx;

   delete [] (Ipp8u*)pCtx2;