Crypto++ How do I use a message authentication code ?

i want use VMAC in crypto++ lib on QT,i was tried study but i dont find example of it

can you help me
can i use Funcition DefaultDecryptorWithMAC ?

Quote:

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FileSource f(in, true, new DefaultDecryptorWithMAC(passPhrase, new FileSink(out)));

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Hi, you can use any C++ library together with Qt (which is just a library itself) so you don't need special examples, any examples you find for crypto++ will be fine.
Crypto++ should provide something.

Ginsengelf

can you help me for VMAC use Crypto++ ?

This isn't a Qt question. You need to post to the crypto++ mailing list if you don't understand how to use the library.

Code:

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void VmacFile(const char *hexKey, const char *hexIV, const char *infile, const char *outfile)
{
	SecByteBlock keyBlock = HexDecodeString(hexKey);
	SecByteBlock iv = HexDecodeString(hexIV);
	VMAC<AES,128 > vmacEncryptFile;
	vmacEncryptFile.SetKeyWithIV(keyBlock, keyBlock.size(), iv);
	CryptoPP::VMAC<CryptoPP::AES, 64> hasher;
	//vmacEncryptFile.Resynchronize(pbIV2);
	FileSource(infile, true, new IteratedHashBase(vmacEncryptFile, new FileSink(outfile)));
}

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Code:

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#include <vector>
#include "vmac.h"
using namespace std;
void TestVMac( int _num, vector<uint64> *_res )
{
	const char key[16] = "somedummykey345";
	const byte pattern[100] = {
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
		if ( sizeof(pattern) < _num )
			_num = sizeof(pattern);
		const uint64 nonce[2] = { 0x10, 0x0 };
		CryptoPP::VMAC<CryptoPP::AES, 64> hasher;
		hasher.SetKey( (byte*)key, 16, CryptoPP::MakeParameters
			( CryptoPP::Name::IV(), (const byte*)&nonce, false )
			( CryptoPP::Name::KeySize(), 128 ) );
		_res->clear();
		for ( size_t i = 1, e = _num; i != e; ++ i )
		{
			uint64 cv;
			hasher.Resynchronize( (const byte*)nonce );
			hasher.CalculateDigest( (byte*)&cv, pattern, i );
			_res->push_back( cv );
		}
} 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
	return a.exec();
}

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Code:

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#include <QtCore/QCoreApplication>
#include "vmac.h"
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <string.h>
 
unsigned prime(void) 
{
    volatile uint64_t i;
    volatile uint64_t j=1;
    unsigned cnt=0;
    volatile clock_t ticks = clock();
    do 
	{
        for (i = 0; i < 500000; i++) 
		{
            uint64_t x = get64PE(&j);
            j = x * x + (uint64_t)ticks;
        }
        cnt++;
    } while (clock() - ticks < (CLOCKS_PER_SEC / 2));
    return cnt;  /* cnt is millions of iterations per second */
}
 
int main(int argc, char *argv[])
{
	QCoreApplication a(argc, argv);
	ALIGN(16) vmac_ctx_t ctx, ctx_aio, ctx_inc1, ctx_inc2;
    uint64_t res, tagl;
    void *p;
    unsigned char *pbData;
    ALIGN(4) unsigned char pbKey[] = "abcdefghijklmnop";
    ALIGN(4) unsigned char nonce[] = "\0\0\0\0\0\0\0\0bcdefghi";
    unsigned int  uiVectorLength[] = {0,3,48,300,3000000};
    #if (VMAC_TAG_LEN == 64)
    ALIGN(4) char *should_be[] = {"2576BE1C56D8B81B","2D376CF5B1813CE5",
                        "E8421F61D573D298","4492DF6C5CAC1BBE",
                        "09BA597DD7601113"};
    #else
    ALIGN(4) char *should_be[] = 
	{                    "472766C70F74ED23481D6D7DE4E80DAC",
                         "4EE815A06A1D71EDD36FC75D51188A42",
                         "09F2C80C8E1007A0C12FAE19FE4504AE",
                         "66438817154850C61D8A412164803BCB",
                         "2B6B02288FFC461B75485DE893C629DC"};
    #endif
    unsigned speed_lengths[] = {16, 32, 64, 128, 256, 512, 1024, 2048, 4096};
    unsigned i, j, *speed_iters;
    clock_t ticks;
    double cpb;
    const unsigned int buf_len = 3 * (1 << 20);   
    j = prime();
    i = sizeof(speed_lengths)/sizeof(speed_lengths[0]);
    speed_iters = (unsigned *)malloc(i*sizeof(speed_iters[0]));
    speed_iters[i-1] = j * (1 << 12);
    while (--i)
	{
		speed_iters[i-1] = (unsigned)(1.3 * speed_iters[i]);
	}
    /* Initialize context and message buffer, all 16-byte aligned */
    p = malloc(buf_len + 32);
    pbData = (unsigned char *)(((size_t)p + 16) & ~((size_t)15));
    memset(pbData, 0, buf_len + 16);
    vmac_set_key(pbKey, &ctx);
    /* Test incremental and all-in-one interfaces for correctness */
    vmac_set_key(pbKey, &ctx_aio);
    vmac_set_key(pbKey, &ctx_inc1);
    vmac_set_key(pbKey, &ctx_inc2); 
    /* Generate vectors */
    for (i = 0; i < sizeof(uiVectorLength)/sizeof(unsigned int); i++) 
	{
        for (j = 0; j < uiVectorLength[i]; j++)
		{
            pbData[j] = (unsigned char)('a'+j%3);
		}
        res = vmac(pbData, uiVectorLength[i], nonce, &tagl, &ctx);
        #if (VMAC_TAG_LEN == 64)
        printf("\'abc\' * %7u: %016llX Should be: %s\n",
              uiVectorLength[i]/3,res,should_be[i]);
        #else
        printf("\'abc\' * %7u: %016llX%016llX\nShould be: %s\n",uiVectorLength[i]/3,res,tagl,should_be[i]);
        #endif
    }
    /* Speed test */
    for (i = 0; i < sizeof(speed_lengths)/sizeof(unsigned int); i++) 
	{
        ticks = clock();
        for (j = 0; j < speed_iters[i]; j++) 
		{
            #if HASH_ONLY
            res = vhash(pbData, speed_lengths[i], &tagl, &ctx);
            #else
            res = vmac(pbData, speed_lengths[i], nonce, &tagl, &ctx);
            nonce[7]++;
            #endif
        }
        ticks = clock() - ticks;
        cpb = ((ticks*VMAC_HZ)/((double)CLOCKS_PER_SEC*speed_lengths[i]*speed_iters[i]));
        printf("%4u bytes, %2.2f cpb\n", speed_lengths[i], cpb);
    }
	return a.exec();
}

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