void WinCAPICryptoHashHMAC::setKey()

in xsec/enc/WinCAPI/WinCAPICryptoHashHMAC.cpp [140:305]
113 lines of code
24 McCabe index (conditional complexity)

void WinCAPICryptoHashHMAC::setKey(const XSECCryptoKey *key) {

	
	BOOL fResult;

	// Use this to initialise the ipadKeyed/opadKeyed values

	if (key->getKeyType() != XSECCryptoKey::KEY_HMAC) {

		throw XSECCryptoException(XSECCryptoException::MDError,
			"WinCAPI:HashHMAC - Non HMAC Key passed to HashHMAC");

	}

	if (m_blockSize > XSEC_MAX_HASH_BLOCK_SIZE) {

		throw XSECCryptoException(XSECCryptoException::MDError,
			"WinCAPI:HashHMAC - Internal error - have got a blocksize bigger than I can handle");

	}

	// Check to see if this is an internal Windows Key
	if (strEquals(key->getProviderName(), DSIGConstants::s_unicodeStrPROVWinCAPI) &&
		((WinCAPICryptoKeyHMAC *) key)->getWinKey() != 0) {

		// Over-ride the local provider for this 

		HCRYPTPROV p = ((WinCAPICryptoKeyHMAC *) key)->getWinKeyProv();
		HCRYPTKEY k = ((WinCAPICryptoKeyHMAC *) key)->getWinKey();

		fResult = CryptCreateHash(
			p,
			CALG_HMAC,
			k,
			0,
			&m_h);

		if (fResult == 0 || m_h == 0) {
			DWORD error = GetLastError();
			throw XSECCryptoException(XSECCryptoException::MDError,
				"WinCAPI:Hash::setKey - Error creating internally keyed hash object"); 
		}

		// Set the HMAC algorithm
		HMAC_INFO hi;

		hi.HashAlgid = m_algId;
		hi.pbInnerString = NULL;		// Use default inner and outer strings
		hi.cbInnerString = 0;
		hi.pbOuterString = NULL;
		hi.cbOuterString = 0;

		fResult = CryptSetHashParam(
			m_h,
			HP_HMAC_INFO,
			(BYTE *) &hi,
			0);

		if (fResult == 0 || m_h == 0) {
			DWORD error = GetLastError();
			throw XSECCryptoException(XSECCryptoException::MDError,
				"WinCAPI:Hash::setKey - Error setting HASH_INFO object"); 
		}



		return;

	}

	// Need to load from raw bit string

	safeBuffer keyBuf;
	unsigned int keyLen = ((XSECCryptoKeyHMAC *) key)->getKey(keyBuf);
	
	if (keyLen > m_blockSize) {

		HCRYPTHASH h;

		fResult = CryptCreateHash(
			m_p,
			m_algId,
			0,
			0,
			&h);

		if (fResult == 0 || h == 0) {
			throw XSECCryptoException(XSECCryptoException::MDError,
				"WinCAPI:Hash::setKey - Error creating hash object"); 
		}

		fResult = CryptHashData(
			h,
			keyBuf.rawBuffer(),
			keyLen,
			0);

		if (fResult == 0 || h == 0) {
			if (h)
				CryptDestroyHash(h);
			throw XSECCryptoException(XSECCryptoException::MDError,
				"WinCAPI:Hash::setKey - Error hashing key data"); 
		}

		BYTE outData[XSEC_MAX_HASH_SIZE];
		DWORD outDataLen = XSEC_MAX_HASH_SIZE;

		CryptGetHashParam(
			h,
			HP_HASHVAL,
			outData,
			&outDataLen,
			0);

		if (fResult == 0 || h == 0) {
			if (h)
				CryptDestroyHash(h);
			throw XSECCryptoException(XSECCryptoException::MDError,
				"WinCAPI:Hash::setKey - Error getting hash result"); 
		}

		keyBuf.sbMemcpyIn(outData, outDataLen);
		keyLen = outDataLen;

		if (h)
			CryptDestroyHash(h);


	}

	// Now create the ipad and opad keyed values
	memcpy(m_ipadKeyed, ipad, m_blockSize);
	memcpy(m_opadKeyed, opad, m_blockSize);

	// XOR with the key
	for (unsigned int i = 0; i < keyLen; ++i) {
		m_ipadKeyed[i] = keyBuf[i] ^ m_ipadKeyed[i];
		m_opadKeyed[i] = keyBuf[i] ^ m_opadKeyed[i];
	}


	// Now create the hash object, and start with the ipad operation
	fResult = CryptCreateHash(
		m_p,
		m_algId,
		0,
		0,
		&m_h);

	if (fResult == 0 || m_h == 0) {
		throw XSECCryptoException(XSECCryptoException::MDError,
			"WinCAPI:HashHMAC - Error creating hash object"); 
	}

	fResult = CryptHashData(
		m_h,
		m_ipadKeyed,
		m_blockSize,
		0);

	if (fResult == 0 || m_h == 0) {
		throw XSECCryptoException(XSECCryptoException::MDError,
			"WinCAPI:HashHMAC - Error performing initial ipad digest"); 
	}

}