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 * All rights reserved.
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 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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/*****************************************************************************
 BotanUtil.h

 Botan convenience functions
 *****************************************************************************/

#include "config.h"
#include "BotanUtil.h"
#include <botan/der_enc.h>
#include <botan/ber_dec.h>
#include <botan/asn1_obj.h>
#include <botan/version.h>

// Convert a Botan BigInt to a ByteString
ByteString BotanUtil::bigInt2ByteString(const Botan::BigInt& bigInt)
{
	ByteString rv;

	rv.resize(bigInt.bytes());
	bigInt.binary_encode(&rv[0]);

	return rv;
}

// Used when extracting little-endian data
ByteString BotanUtil::bigInt2ByteStringPrefix(const Botan::BigInt& bigInt, size_t size)
{
	ByteString rv;

	if (size > bigInt.bytes())
	{
		size_t diff = size - bigInt.bytes();
		rv.resize(size);

		memset(&rv[0], '\0', diff);

		bigInt.binary_encode(&rv[0] + diff);
	}
	else
	{
		rv.resize(bigInt.bytes());
		bigInt.binary_encode(&rv[0]);
	}

	return rv;
}

// Convert a ByteString to an Botan BigInt
Botan::BigInt BotanUtil::byteString2bigInt(const ByteString& byteString)
{
	return Botan::BigInt(byteString.const_byte_str(), byteString.size());
}

#if defined(WITH_ECC) || defined(WITH_GOST)
// Convert a Botan EC group to a ByteString
ByteString BotanUtil::ecGroup2ByteString(const Botan::EC_Group& ecGroup)
{
#if BOTAN_VERSION_CODE >= BOTAN_VERSION_CODE_FOR(1,11,0)
	std::vector<Botan::byte> der = ecGroup.DER_encode(Botan::EC_DOMPAR_ENC_OID);
#else
	Botan::SecureVector<Botan::byte> der = ecGroup.DER_encode(Botan::EC_DOMPAR_ENC_OID);
#endif
	return ByteString(&der[0], der.size());
}

// Convert a ByteString to a Botan EC group
Botan::EC_Group BotanUtil::byteString2ECGroup(const ByteString& byteString)
{
#if BOTAN_VERSION_CODE >= BOTAN_VERSION_CODE_FOR(1,11,0)
	std::vector<Botan::byte> der(byteString.size());
	memcpy(&der[0], byteString.const_byte_str(), byteString.size());
	return Botan::EC_Group(der);
#else
	return Botan::EC_Group(Botan::MemoryVector<Botan::byte>(byteString.const_byte_str(), byteString.size()));
#endif
}

// Convert a Botan EC point to a ByteString
ByteString BotanUtil::ecPoint2ByteString(const Botan::PointGFp& ecPoint)
{
	ByteString point;

	try
	{
#if BOTAN_VERSION_CODE >= BOTAN_VERSION_CODE_FOR(1,11,0)
		Botan::secure_vector<Botan::byte> repr = Botan::EC2OSP(ecPoint, Botan::PointGFp::UNCOMPRESSED);
		Botan::secure_vector<Botan::byte> der;
#else
		Botan::SecureVector<Botan::byte> repr = Botan::EC2OSP(ecPoint, Botan::PointGFp::UNCOMPRESSED);
		Botan::SecureVector<Botan::byte> der;
#endif


		der = Botan::DER_Encoder()
			.encode(repr, Botan::OCTET_STRING)
			.get_contents();
		point.resize(der.size());
		memcpy(&point[0], &der[0], der.size());
	}
	catch (...)
	{
		ERROR_MSG("Can't convert from EC point");
	}
	return point;
}

// Convert a ByteString to a Botan EC point
Botan::PointGFp BotanUtil::byteString2ECPoint(const ByteString& byteString, const Botan::EC_Group& ecGroup)
{
#if BOTAN_VERSION_CODE >= BOTAN_VERSION_CODE_FOR(1,11,0)
	std::vector<Botan::byte> repr;
#else
	Botan::SecureVector<Botan::byte> repr;
#endif
	Botan::BER_Decoder(byteString.const_byte_str(), byteString.size())
		.decode(repr, Botan::OCTET_STRING)
		.verify_end();
	return Botan::OS2ECP(&repr[0], repr.size(), ecGroup.get_curve());
}
#endif