/*

* Copyright (c) 2001-2006 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  EAP and WLAN authentication protocols.

*

*/

/*

*/

// This is enumeration of EAPOL source code.

#if defined(USE_EAP_MINIMUM_RELEASE_TRACES)

	#undef EAP_FILE_NUMBER_ENUM

	#define EAP_FILE_NUMBER_ENUM 8 

	#undef EAP_FILE_NUMBER_DATE 

	#define EAP_FILE_NUMBER_DATE 1127594498 

#endif //#if defined(USE_EAP_MINIMUM_RELEASE_TRACES)

#include "eap_am_memory.h"

#include "dss_random.h"

#include "eap_am_assert.h"

#include "abs_eap_am_crypto.h"

#include <openssl/bn.h>

#include "eap_am_crypto_sha1.h"

/** @file */

/** This is the block size in bytes. */

static const u32_t BLOCK_SIZE = 160/8;

static const u32_t DEBUG_BUFFER_SIZE = 80;

/**

 *  dss_random_G() implements the G() function using modified SHA-1.

 *  @code

 *  Copied from "Multiple Examples of DSA" http://csrc.nist.gov/encryption/dss/Examples-1024bit.pdf.

 *  Using the revised algorithm found in the Change Notice for the generation of x values:

 *      XKEY= bd029bbe 7f51960b cf9edb2b 61f06f0f eb5a38b6

 *      XSEED= 00000000 00000000 00000000 00000000 00000000

 *  The first loop through step 3.2 provides:

 *      XVAL= bd029bbe 7f51960b cf9edb2b 61f06f0f eb5a38b6

 *  Using the routine in Appendix 3.3 Constructing The Function G From SHA-1

 *  provides:

 *      w[0]= 2070b322 3dba372f de1c0ffc 7b2e3b49 8b260614

 *  The following value is the updated XKEY value from step 3.2.c:

 *      XKEY= dd734ee0 bd0bcd3b adbaeb27 dd1eaa59 76803ecb

 *  The second loop through step 3.2 provides:

 *      XVAL= dd734ee0 bd0bcd3b adbaeb27 dd1eaa59 76803ecb

 *  Using the routine in Appendix 3.3 Constructing The Function G From SHA-1

 *  provides:

 *      w[1]= 3c6c18ba cb0f6c55 babb1378 8e20d737 a3275116

 *  The following value is the updated XKEY value from step 3.2.c:

 *      XKEY= 19df679b 881b3991 6875fea0 6b3f8191 19a78fe2

 *  Step 3.3 provides the following values:

 *      w[0] || w[1]= 2070b322 3dba372f de1c0ffc 7b2e3b49 8b260614

 *                    3c6c18ba cb0f6c55 babb1378 8e20d737 a3275116

 *      X= 47c27eb6 16dba413 91e5165b e9c5e397 7e39a15d

 *  @endcode

*/

{

	u32_t *out_array = reinterpret_cast<u32_t *>(out);

	EAP_ASSERT(out_length == BLOCK_SIZE);

	EAP_ASSERT(c_length == BLOCK_SIZE);

	{

		eap_am_crypto_sha1_c sha1(m_am_tools);

		u32_t output_length = out_length;

		eap_status_e status = sha1.eap_sha1_dss_G_function(

			c,

			c_length,

			out_array,

			&output_length

			);

		if (status != eap_status_ok)

		{

				status));

		}

	}

}

/**

 *  dss_pseudo_random() implements pseudo random function for key genearation of EAP/SIM.

 *  @code

 *  Random generator becomes as follows:

 *  Step 1. Choose a new, secret value for the seed-key, XKEY.

 *  Step 2. In hexadecimal notation let

 *              t = 67452301 EFCDAB89 98BADCFE 10325476 C3D2E1F0.

 *              This is the initial value for H0 || H1 || H2 || H3 || H4 in the SHS.

 *  Step 3. For j = 0 to m - 1 do

 *              c. xj = G(t,XKEY).

 *              d. XKEY = (1 + XKEY + xj) mod 2^b.

 *  @endcode

*/

eap_status_e dss_pseudo_random(abs_eap_am_tools_c * const m_am_tools, u8_t *out, u32_t out_length, u8_t *xkey, u32_t xkey_length)

{

	u32_t block_count = out_length/BLOCK_SIZE;

	if ((out_length % BLOCK_SIZE) != 0)

	{

		EAP_TRACE_DEBUG(

			m_am_tools, 

			TRACE_FLAGS_DEFAULT, 

			(EAPL("ERROR: dss_pseudo_random(): out buffer length 0x%08x not aligned to 0x%08x.\n"),

			 out_length, BLOCK_SIZE));

		return eap_status_data_length_not_aligned_to_block_size;

	}

	if (xkey == 0

		|| out == 0)

	{

		return eap_status_illegal_parameter;

	}

	u8_t tmp_xkey[BLOCK_SIZE];

	m_am_tools->memmove(tmp_xkey, xkey, BLOCK_SIZE);

	BN_CTX *ctx;

	BIGNUM bn_mod, bn_xkey, bn_xj, bn_one, bn_160, bn_tmp;

	ctx=BN_CTX_new();

	BN_init(&bn_mod);

	BN_init(&bn_tmp);

	BN_init(&bn_xkey);

	BN_init(&bn_xj);

	BN_init(&bn_one);

	BN_init(&bn_160);

	BN_set_word(&bn_one, 1);

	BN_set_word(&bn_mod, 2);

	BN_set_word(&bn_160, 160);

	// bn_mod = 2^160

	BN_exp(&bn_mod, &bn_mod, &bn_160, ctx);

	EAP_TRACE_DATA_DEBUG(m_am_tools, TRACE_FLAGS_EAP_AM_CRYPTO, (EAPL("dss_pseudo_random(): mod"),

		bn_mod.d, bn_mod.top*sizeof(BN_ULONG)));

	EAP_TRACE_DATA_DEBUG(m_am_tools, TRACE_FLAGS_EAP_AM_CRYPTO, (EAPL("xkey[0]"),

		xkey, xkey_length));

	for (u32_t ind = 0; ind < block_count; ind++)

	{

		u8_t debug_buffer[DEBUG_BUFFER_SIZE];

		EAP_UNREFERENCED_PARAMETER(debug_buffer);

		EAP_TRACE_FORMAT(m_am_tools, (debug_buffer, DEBUG_BUFFER_SIZE, EAPL("w[%d]   "), ind));

		EAP_TRACE_DEBUG(m_am_tools, TRACE_FLAGS_EAP_AM_CRYPTO, (EAPL("dss_pseudo_random(): %s = G(xkey[%d])\n"),

			debug_buffer,

			ind));

		EAP_TRACE_DATA_DEBUG(m_am_tools, TRACE_FLAGS_EAP_AM_CRYPTO, (reinterpret_cast<eap_format_string>(debug_buffer),

			&(out[ind*BLOCK_SIZE]), BLOCK_SIZE));

		if (ind+1u >= block_count)

		{

			break;

		}

		BN_bin2bn(static_cast<u8_t *>(tmp_xkey), BLOCK_SIZE, &bn_xkey);

		// tmp = (xkey + 1) % mod

		BN_mod_add(&bn_tmp, &bn_xkey, &bn_one, &bn_mod, ctx);

		EAP_TRACE_DEBUG(m_am_tools, TRACE_FLAGS_EAP_AM_CRYPTO, (EAPL("dss_pseudo_random(): tmp[%d] = (xkey[%d] + 1) % mod\n"),

			ind,

			ind));

		EAP_TRACE_FORMAT(m_am_tools, (debug_buffer, DEBUG_BUFFER_SIZE, EAPL("tmp[%d] "), ind));

		EAP_TRACE_DATA_DEBUG(m_am_tools, TRACE_FLAGS_EAP_AM_CRYPTO, (reinterpret_cast<eap_format_string>(debug_buffer),

			bn_tmp.d, bn_tmp.top*sizeof(BN_ULONG)));

		BN_bin2bn(static_cast<u8_t *>(&(out[ind*BLOCK_SIZE])), BLOCK_SIZE, &bn_xj);

		// xkey = (tmp + xj) % mod

		BN_mod_add(&bn_xkey, &bn_tmp, &bn_xj, &bn_mod, ctx);

		BN_bn2bin(&bn_xkey, static_cast<u8_t *>(tmp_xkey));

		EAP_TRACE_DEBUG(m_am_tools, TRACE_FLAGS_EAP_AM_CRYPTO, (EAPL("dss_pseudo_random(): xkey[%d] = (tmp + x[%d]) % mod\n"),

			ind+1u,

			ind));

		EAP_TRACE_FORMAT(m_am_tools, (debug_buffer, DEBUG_BUFFER_SIZE, EAPL("xkey[%d]"), ind+1u));

		EAP_TRACE_DATA_DEBUG(m_am_tools, TRACE_FLAGS_EAP_AM_CRYPTO, (reinterpret_cast<eap_format_string>(debug_buffer),

			tmp_xkey, sizeof(tmp_xkey)));

	}

	return eap_status_ok;

}

// End.