开源项目之NeoCrypt

一个文件加密解密软件的源代码，可以设置很多著名的加密算法进行加密解密。它集强力、安全的算法和简单、易用的界面于一身。它的文件管理界面可以轻易地观看和更改整个系 统的加密设置，也可以加/解密选定的文件，安全地删除文件。它支持多用户使用。如图：

项目需要用到第三方库cryptlib，该库已经放到源码包中。

本程序有一个动态链接库NeoCryptSX与一个主程序Neocrypt组成，NeoCryptSX动态库操作简单，只负责发送调用消息，Neocrypt主程序中封装了Decryptor类负责解码、Encryptor类负责编码，File类负责文件操作、CProgUpdater类负责进度等。

解码部分：

void Decryptor::decrypt(const std::string& name,std::list<std::string>& pwds)
{
	char* buf = new char[BUFFER_SIZE];

	File file(name);

	// pass file size to listener
	if (mListener)
		mListener->setRange(file.size());

	// check for password
	if (pwds.size() == 0)
		throw std::logic_error("No passwords specified!");

	// create the envelope
	CRYPT_ENVELOPE env;
	if (cryptCreateEnvelope(&env,CRYPT_UNUSED,CRYPT_FORMAT_AUTO))
		throw std::runtime_error("Failed to create envelope!");

	cryptSetAttribute(env,CRYPT_ATTRIBUTE_BUFFERSIZE,BUFFER_SIZE);

	int n;

	while (!file.eof() && (n = file.read(buf,BUFFER_SIZE-4096)) != 0)
	{
		int cBytes;
		int bytesDone = 0;
		int bytesLeft = n;

		while (bytesLeft)
		{
			int status = cryptPushData(env,buf+bytesDone,bytesLeft,&cBytes);
			if ( status == CRYPT_ENVELOPE_RESOURCE)
			{
				// add passwords until one is accepted
				std::list<std::string>::iterator it;
				std::list<std::string>::iterator end = pwds.end();

				for (it = pwds.begin(); it != end; ++it)
				{
					// loop through all required attributes and try the password with each
					if (cryptSetAttribute(env,CRYPT_ENVINFO_PASSWORD,CRYPT_CURSOR_FIRST) == CRYPT_OK)
					{
						bool accept = false;

						do
						{
							CRYPT_ATTRIBUTE_TYPE attrib;
							cryptGetAttribute(env,CRYPT_ENVINFO_PASSWORD,(int*)&attrib);

							if (attrib == CRYPT_ENVINFO_PASSWORD)
							{
								if (cryptSetAttributeString(env,CRYPT_ENVINFO_PASSWORD,it->c_str(),it->size()) == CRYPT_OK)
								{
									accept = true;
									break;
								}
							}
						}
						while (cryptSetAttribute(env,CRYPT_ENVINFO_PASSWORD,CRYPT_CURSOR_NEXT) == CRYPT_OK);

						if (accept)
							break;
					}
				}

				if (it == end)
					throw std::runtime_error("None of the passwords are valid for file " + name + " ! Please try another password.");
			}
			else if (status != 0)
			{
				throw std::runtime_error("The given file " + name + " is not a valid encrypted file.");
			}

			bytesLeft -= cBytes;
			bytesDone += cBytes;

			cryptPopData(env,buf,BUFFER_SIZE,&cBytes);
			file.write(buf,cBytes);
		}

		if (mListener)
			mListener->increment(n);
	}

	// flush remaining data
	cryptFlushData(env);

	cryptPopData(env,buf,BUFFER_SIZE,&n);
	file.write(buf,n);

	// destroy envelope
	cryptDestroyEnvelope(env);

	// close file
	file.close();

	mListener->complete();

	delete [] buf;
}

void Encryptor::encrypt(const std::string& name,std::list<std::string>& password,Algorithm::Type algo)
{
	char* buf = new char[BUFFER_SIZE];

	File file(name);

	// pass file size to listener
	if (mListener)
		mListener->setRange(file.size());

	// check for at-least one password
	if (password.size() == 0)
		throw std::logic_error("No password in password list!");

	// set algorithm type
	if (cryptSetAttribute(CRYPT_UNUSED,CRYPT_OPTION_ENCR_ALGO,algo))
		throw std::runtime_error("Could not set algorithm type!");

	// create the envelope
	CRYPT_ENVELOPE env;
	if (cryptCreateEnvelope(&env,CRYPT_UNUSED,CRYPT_FORMAT_CRYPTLIB))
		throw std::runtime_error("Failed to create envelope!");

	std::list<std::string>::iterator i;
	std::list<std::string>::iterator e = password.end();

	// add password(s)
	for (i = password.begin(); i != e; ++i)
	{
		if (cryptSetAttributeString(env,CRYPT_ENVINFO_PASSWORD,(*i).c_str(),(*i).size()))
			throw std::runtime_error("Failed to set password " + (*i) + "!");
	}

	// allocate encryption buffer
	if (cryptSetAttribute(env,CRYPT_ATTRIBUTE_BUFFERSIZE,BUFFER_SIZE))
		throw std::runtime_error("Could not allocate encryption buffer!");

	int n;
	int cBytes;

	if (!file.eof() && (n = file.read(buf,100)) != 0)
	{
		cryptPushData(env,buf,n,&cBytes);

		cryptPopData(env,buf,BUFFER_SIZE,&cBytes);
		file.write(buf,cBytes);

		if (mListener)
			mListener->increment(n);
	}

	while (!file.eof() && (n = file.read(buf,BUFFER_SIZE-4096)) != 0)
	{
		cryptPushData(env,buf,n,&cBytes);

		cryptPopData(env,buf,BUFFER_SIZE,&cBytes);
		file.write(buf,cBytes);

		if (mListener)
			mListener->increment(n);
	}

	// flush remaining data
	cryptFlushData(env);

	cryptPopData(env,buf,BUFFER_SIZE,&cBytes);
	file.write(buf,cBytes);

	// destroy envelope
	cryptDestroyEnvelope(env);

	// close file
	file.close();

	mListener->complete();

	delete [] buf;
}