void GenerateRSAKey(unsigned int keyLength, const char *privFilename, const char *pubFilename, const char *seed)
{
	RandomPool randPool;
	randPool.Put((byte *)seed, strlen(seed));

	RSAES_OAEP_SHA_Decryptor priv(randPool, keyLength);
	HexEncoder privFile(new FileSink(privFilename));
	priv.DEREncode(privFile);
	privFile.MessageEnd();

	RSAES_OAEP_SHA_Encryptor pub(priv);
	HexEncoder pubFile(new FileSink(pubFilename));
	pub.DEREncode(pubFile);
	pubFile.MessageEnd();
}

char *RSAEncryptString(const char *pubFilename, const char *seed, const char *message)
{
	FileSource pubFile(pubFilename, true, new HexDecoder);
	RSAES_OAEP_SHA_Encryptor pub(pubFile);

	if (strlen(message) > pub.MaxPlainTextLength())
	{
		cerr << "message too long for this key\n";
		abort();
	}

	RandomPool randPool;
	randPool.Put((byte *)seed, strlen(seed));

	char *outstr = new char[2*pub.CipherTextLength()+1];
	pub.Encrypt(randPool, (byte *)message, strlen(message), (byte *)outstr);

	HexEncoder hexEncoder;
	hexEncoder.Put((byte *)outstr, pub.CipherTextLength());
	hexEncoder.MessageEnd();
	hexEncoder.Get((byte *)outstr, 2*pub.CipherTextLength());

	outstr[2*pub.CipherTextLength()] = 0;
	return outstr;
}

char *RSADecryptString(const char *privFilename, const char *ciphertext)
{
	FileSource privFile(privFilename, true, new HexDecoder);
	RSAES_OAEP_SHA_Decryptor priv(privFile);

	HexDecoder hexDecoder;
	hexDecoder.Put((byte *)ciphertext, strlen(ciphertext));
	hexDecoder.MessageEnd();
	SecByteBlock buf(priv.CipherTextLength());
	hexDecoder.Get(buf, priv.CipherTextLength());

	char *outstr = new char[priv.MaxPlainTextLength()+1];
	unsigned messageLength = priv.Decrypt(buf, (byte *)outstr);
	outstr[messageLength] = 0;
	return outstr;
}

void RSASignFile(const char *privFilename, const char *messageFilename, const char *signatureFilename)
{
	FileSource privFile(privFilename, true, new HexDecoder);
	RSASSA_PKCS1v15_SHA_Signer priv(privFile);
	NullRNG rng;	// RSASSA_PKCS1v15_SHA_Signer ignores the rng. Use a real RNG for other signature schemes!
	FileSource f(messageFilename, true, new SignerFilter(rng, priv, new HexEncoder(new FileSink(signatureFilename))));
}

bool RSAVerifyFile(const char *pubFilename, const char *messageFilename, const char *signatureFilename)
{
	FileSource pubFile(pubFilename, true, new HexDecoder);
	RSASSA_PKCS1v15_SHA_Verifier pub(pubFile);

	FileSource signatureFile(signatureFilename, true, new HexDecoder);
	if (signatureFile.MaxRetrievable() != pub.SignatureLength())
		return false;
	SecByteBlock signature(pub.SignatureLength());
	signatureFile.Get(signature, signature.size);

	VerifierFilter *verifierFilter = new VerifierFilter(pub);
	verifierFilter->PutSignature(signature);
	FileSource f(messageFilename, true, verifierFilter);

	byte result = 0;
	f.Get(result);
	return result == 1;
}