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Implementation of the Licensing System for a Software Product

, , 5 Aug 2010
This article is devoted to the development of the key licensing system for the applications.
bin.zip
bin
ClientTest.exe
DigitalSignature.exe
src.zip
src
src
ClientTest
keys
public.bin
cryptopp560
adhoc.cpp.copied
adhoc.cpp.proto
cryptdll.dsp
cryptest.dsp
cryptest.dsw
cryptest_bds.bdsgroup
cryptest_bds.bdsproj
cryptest_bds.bpf
cryptlib.dsp
cryptlib_bds.bdsproj
dlltest.dsp
Doxyfile
GNUmakefile
DigitalSignature
keys
private.bin
public.bin
Utils
// cmac.cpp - written and placed in the public domain by Wei Dai

#include "pch.h"

#ifndef CRYPTOPP_IMPORTS

#include "cmac.h"

NAMESPACE_BEGIN(CryptoPP)

static void MulU(byte *k, unsigned int length)
{
	byte carry = 0;

	for (int i=length-1; i>=1; i-=2)
	{
		byte carry2 = k[i] >> 7;
		k[i] += k[i] + carry;
		carry = k[i-1] >> 7;
		k[i-1] += k[i-1] + carry2;
	}

	if (carry)
	{
		switch (length)
		{
		case 8:
			k[7] ^= 0x1b;
			break;
		case 16:
			k[15] ^= 0x87;
			break;
		case 32:
			k[30] ^= 4; 
			k[31] ^= 0x23;
			break;
		default:
			throw InvalidArgument("CMAC: " + IntToString(length) + " is not a supported cipher block size");
		}
	}
}

void CMAC_Base::UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params)
{
	BlockCipher &cipher = AccessCipher();
	unsigned int blockSize = cipher.BlockSize();

	cipher.SetKey(key, length, params);
	m_reg.CleanNew(3*blockSize);
	m_counter = 0;

	cipher.ProcessBlock(m_reg, m_reg+blockSize);
	MulU(m_reg+blockSize, blockSize);
	memcpy(m_reg+2*blockSize, m_reg+blockSize, blockSize);
	MulU(m_reg+2*blockSize, blockSize);
}

void CMAC_Base::Update(const byte *input, size_t length)
{
	if (!length)
		return;

	BlockCipher &cipher = AccessCipher();
	unsigned int blockSize = cipher.BlockSize();

	if (m_counter > 0)
	{
		unsigned int len = UnsignedMin(blockSize - m_counter, length);
		xorbuf(m_reg+m_counter, input, len);
		length -= len;
		input += len;
		m_counter += len;

		if (m_counter == blockSize && length > 0)
		{
			cipher.ProcessBlock(m_reg);
			m_counter = 0;
		}
	}

	if (length > blockSize)
	{
		assert(m_counter == 0);
		size_t leftOver = 1 + cipher.AdvancedProcessBlocks(m_reg, input, m_reg, length-1, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
		input += (length - leftOver);
		length = leftOver;
	}

	if (length > 0)
	{
		assert(m_counter + length <= blockSize);
		xorbuf(m_reg+m_counter, input, length);
		m_counter += (unsigned int)length;
	}

	assert(m_counter > 0);
}

void CMAC_Base::TruncatedFinal(byte *mac, size_t size)
{
	ThrowIfInvalidTruncatedSize(size);

	BlockCipher &cipher = AccessCipher();
	unsigned int blockSize = cipher.BlockSize();

	if (m_counter < blockSize)
	{
		m_reg[m_counter] ^= 0x80;
		cipher.AdvancedProcessBlocks(m_reg, m_reg+2*blockSize, m_reg, blockSize, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);
	}
	else
		cipher.AdvancedProcessBlocks(m_reg, m_reg+blockSize, m_reg, blockSize, BlockTransformation::BT_DontIncrementInOutPointers|BlockTransformation::BT_XorInput);

	memcpy(mac, m_reg, size);

	m_counter = 0;
	memset(m_reg, 0, blockSize);
}

NAMESPACE_END

#endif

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About the Authors

Apriorit Inc
Apriorit Inc.
Ukraine Ukraine
ApriorIT is a Software Research and Development company that works in advanced knowledge-intensive scopes.
 
Company offers integrated research&development services for the software projects in such directions as Corporate Security, Remote Control, Mobile Development, Embedded Systems, Virtualization, Drivers and others.
 
Official site http://www.apriorit.com
Group type: Organisation

31 members

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Sergii Bratus
Software Developer Apriorit Inc.
Ukraine Ukraine
No Biography provided

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