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path: root/ed25519/ed25519_fpga_curve_microcode.cpp
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//------------------------------------------------------------------------------
//
// ed25519_fpga_curve_microcode.cpp
// -----------------------------------------------
// Elliptic curve arithmetic procedures for Ed25519
//
// Authors: Pavel Shatov
//
// Copyright (c) 2018 NORDUnet A/S
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// - Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
//
// - Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
//
// - Neither the name of the NORDUnet nor the names of its contributors may be
//   used to endorse or promote products derived from this software without
//   specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR 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 COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
//------------------------------------------------------------------------------


//------------------------------------------------------------------------------
// Headers
//------------------------------------------------------------------------------
#include "ed25519_fpga_model.h"


//------------------------------------------------------------------------------
enum ED25519_UOP_OPERAND
//------------------------------------------------------------------------------
{
	CONST_G_X = CURVE25519_UOP_OPERAND_COUNT + 1,
	CONST_G_Y,
	CONST_G_T,
	
	CYCLE_R0_X,
	CYCLE_R0_Y,
	CYCLE_R0_Z,
	CYCLE_R0_T,
	
	CYCLE_R1_X,
	CYCLE_R1_Y,
	CYCLE_R1_Z,
	CYCLE_R1_T,
	
	CYCLE_S_X,
	CYCLE_S_Y,
	CYCLE_S_Z,
	CYCLE_S_T,
	
	CYCLE_T_X,
	CYCLE_T_Y,
	CYCLE_T_Z,
	CYCLE_T_T,
	
	CYCLE_U_X,
	CYCLE_U_Y,
	CYCLE_U_Z,
	CYCLE_U_T,
	
	CYCLE_V_X,
	CYCLE_V_Y,
	CYCLE_V_Z,
	CYCLE_V_T,
	
	PROC_A,
	PROC_B,
	PROC_C,
	PROC_D,
	PROC_E,
	PROC_F,
	PROC_G,
	PROC_H,
	PROC_I,
	PROC_J,

	ED25519_UOP_OPERAND_COUNT
};


//------------------------------------------------------------------------------
// Storage Buffers
//------------------------------------------------------------------------------
static FPGA_BUFFER BUF_LO[ED25519_UOP_OPERAND_COUNT];
static FPGA_BUFFER BUF_HI[ED25519_UOP_OPERAND_COUNT];


//------------------------------------------------------------------------------
//
// Elliptic curve point scalar multiplication routine.
//
//------------------------------------------------------------------------------
void fpga_curve_ed25519_base_scalar_multiply_microcode(const FPGA_BUFFER *K, FPGA_BUFFER *QY)
//------------------------------------------------------------------------------
{
	bool k_bit;					// 1-bit values
	FPGA_WORD k_word;			// current word of multiplier
	int word_count, bit_count;	// counters

		// initialize internal banks
	fpga_multiword_copy(&CURVE25519_ZERO, &BUF_LO[CONST_ZERO]);
	fpga_multiword_copy(&CURVE25519_ZERO, &BUF_HI[CONST_ZERO]);

	fpga_multiword_copy(&CURVE25519_ONE, &BUF_LO[CONST_ONE]);
	fpga_multiword_copy(&CURVE25519_ONE, &BUF_HI[CONST_ONE]);

	fpga_multiword_copy(&ED25519_G_X, &BUF_LO[CONST_G_X]);
	fpga_multiword_copy(&ED25519_G_X, &BUF_HI[CONST_G_X]);

	fpga_multiword_copy(&ED25519_G_Y, &BUF_LO[CONST_G_Y]);
	fpga_multiword_copy(&ED25519_G_Y, &BUF_HI[CONST_G_Y]);

	fpga_multiword_copy(&ED25519_G_T, &BUF_LO[CONST_G_T]);
	fpga_multiword_copy(&ED25519_G_T, &BUF_HI[CONST_G_T]);

		// force certain bit values
	FPGA_BUFFER K_INT;
	fpga_multiword_copy(K, &K_INT);

	K_INT.words[0] &= 0xFFFFFFF8;
	K_INT.words[FPGA_OPERAND_NUM_WORDS-1] &= 0x3FFFFFFF;
	K_INT.words[FPGA_OPERAND_NUM_WORDS-1] |= 0x40000000;

		// initialization
	uop_move(BANK_HI, CONST_ZERO, BANK_LO, CYCLE_R0_X, BUF_LO, BUF_HI);
	uop_move(BANK_HI, CONST_ONE,  BANK_LO, CYCLE_R0_Y, BUF_LO, BUF_HI);
	uop_move(BANK_HI, CONST_ONE,  BANK_LO, CYCLE_R0_Z, BUF_LO, BUF_HI);
	uop_move(BANK_HI, CONST_ZERO, BANK_LO, CYCLE_R0_T, BUF_LO, BUF_HI);

	uop_move(BANK_HI, CONST_G_X, BANK_LO, CYCLE_R1_X, BUF_LO, BUF_HI);
	uop_move(BANK_HI, CONST_G_Y, BANK_LO, CYCLE_R1_Y, BUF_LO, BUF_HI);
	uop_move(BANK_HI, CONST_ONE, BANK_LO, CYCLE_R1_Z, BUF_LO, BUF_HI);
	uop_move(BANK_HI, CONST_G_T, BANK_LO, CYCLE_R1_T, BUF_LO, BUF_HI);

		// multiply
	for (word_count=0; word_count<FPGA_OPERAND_NUM_WORDS; word_count++)
	{
		for (bit_count=0; bit_count<FPGA_WORD_WIDTH; bit_count++)
		{
				// get current bit of K
			k_word = K_INT.words[word_count] >> bit_count;
			k_bit = (k_word & (FPGA_WORD)1) == 1;

			if (k_bit)
			{
				// U = R0
				// V = R1

				uop_move(BANK_LO, CYCLE_R0_X, BANK_HI, CYCLE_U_X, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R0_Y, BANK_HI, CYCLE_U_Y, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R0_Z, BANK_HI, CYCLE_U_Z, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R0_T, BANK_HI, CYCLE_U_T, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R1_X, BANK_HI, CYCLE_V_X, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R1_Y, BANK_HI, CYCLE_V_Y, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R1_Z, BANK_HI, CYCLE_V_Z, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R1_T, BANK_HI, CYCLE_V_T, BUF_LO, BUF_HI);
			}
			else
			{
				// U = R1
				// V = R0

				uop_move(BANK_LO, CYCLE_R0_X, BANK_HI, CYCLE_V_X, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R0_Y, BANK_HI, CYCLE_V_Y, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R0_Z, BANK_HI, CYCLE_V_Z, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R0_T, BANK_HI, CYCLE_V_T, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R1_X, BANK_HI, CYCLE_U_X, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R1_Y, BANK_HI, CYCLE_U_Y, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R1_Z, BANK_HI, CYCLE_U_Z, BUF_LO, BUF_HI);
				uop_move(BANK_LO, CYCLE_R1_T, BANK_HI, CYCLE_U_T, BUF_LO, BUF_HI);
			}

				// S = double(U)
			uop_calc(MUL, BANK_HI,  CYCLE_U_X, CYCLE_U_X, BANK_LO, PROC_A, BUF_LO, BUF_HI,    MOD_2P);		// fpga_modular_mul(P_X, P_X,  &A, &CURVE25519_2P);
			uop_calc(MUL, BANK_HI,  CYCLE_U_Y, CYCLE_U_Y, BANK_LO, PROC_B, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_mul(P_Y, P_Y,  &B, &CURVE25519_2P);

			uop_calc(MUL, BANK_HI,  CYCLE_U_Z, CYCLE_U_Z, BANK_LO, PROC_I, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_mul(P_Z, P_Z,  &I, &CURVE25519_2P);
			uop_calc(ADD, BANK_LO,  PROC_I,    PROC_I,    BANK_HI, PROC_C, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_add( &I,  &I,  &C, &CURVE25519_2P);
			uop_calc(ADD, BANK_HI,  CYCLE_U_X, CYCLE_U_Y, BANK_LO, PROC_I, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_add(P_X, P_Y,  &I, &CURVE25519_2P);
			uop_calc(MUL, BANK_LO,  PROC_I,    PROC_I,    BANK_HI, PROC_D, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_mul( &I,  &I,  &D, &CURVE25519_2P);

			uop_calc(ADD, BANK_LO,  PROC_A,    PROC_B,    BANK_HI, PROC_H, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_add( &A,  &B,  &H, &CURVE25519_2P);
			uop_calc(SUB, BANK_HI,  PROC_H,    PROC_D,    BANK_LO, PROC_E, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_sub( &H,  &D,  &E, &CURVE25519_2P);
			uop_calc(SUB, BANK_LO,  PROC_A,    PROC_B,    BANK_HI, PROC_G, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_sub( &A,  &B,  &G, &CURVE25519_2P);
			uop_calc(ADD, BANK_HI,  PROC_C,    PROC_G,    BANK_LO, PROC_F, BUF_LO, BUF_HI,     MOD_2P);		// fpga_modular_add( &C,  &G,  &F, &CURVE25519_2P);

			uop_move2(BANK_HI, PROC_G, PROC_H, BANK_LO, PROC_G, PROC_H, BUF_LO, BUF_HI);

			uop_calc(MUL, BANK_LO,  PROC_E,    PROC_F,    BANK_HI, CYCLE_S_X, BUF_LO, BUF_HI,  MOD_2P);		// fpga_modular_mul( &E,  &F, Q_X, &CURVE25519_2P);
			uop_calc(MUL, BANK_LO,  PROC_G,    PROC_H,    BANK_HI, CYCLE_S_Y, BUF_LO, BUF_HI,  MOD_2P);		// fpga_modular_mul( &G,  &H, Q_Y, &CURVE25519_2P);

			uop_calc(MUL, BANK_LO,  PROC_E,    PROC_H,    BANK_HI, CYCLE_S_T, BUF_LO, BUF_HI,  MOD_2P);		// fpga_modular_mul( &E,  &H, Q_T, &CURVE25519_2P);
			uop_calc(MUL, BANK_LO,  PROC_F,    PROC_G,    BANK_HI, CYCLE_S_Z, BUF_LO, BUF_HI,  MOD_2P);		// fpga_modular_mul( &F,  &G, Q_Z, &CURVE25519_2P);

				// T = add(S, V)
			uop_calc(SUB, BANK_HI, CYCLE_S_Y, CYCLE_S_X, BANK_LO, PROC_I, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_sub(S_Y, S_X,  &I, &CURVE25519_2P);	// I = (qy - qx) % mod
			uop_calc(ADD, BANK_HI, CYCLE_V_Y, CYCLE_V_X, BANK_LO, PROC_J, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_add(V_Y, V_X,  &J, &CURVE25519_2P);	// J = (py + px) % mod
			uop_calc(MUL, BANK_LO, PROC_I,    PROC_J,    BANK_HI, PROC_A, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_mul( &I,  &J,  &A, &CURVE25519_2P);	// A = ( I *  J) % mod

			uop_calc(ADD, BANK_HI, CYCLE_S_Y, CYCLE_S_X, BANK_LO, PROC_I, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_add(S_Y, S_X,  &I, &CURVE25519_2P);	// I = (qy + qx) % mod
			uop_calc(SUB, BANK_HI, CYCLE_V_Y, CYCLE_V_X, BANK_LO, PROC_J, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_sub(V_Y, V_X,  &J, &CURVE25519_2P);	// J = (py - px) % mod
			uop_calc(MUL, BANK_LO, PROC_I,    PROC_J,    BANK_HI, PROC_B, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_mul( &I,  &J,  &B, &CURVE25519_2P);	// B = ( I *  J) % mod

			uop_calc(MUL, BANK_HI, CYCLE_S_Z, CYCLE_V_T, BANK_LO, PROC_I, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_mul(S_Z, V_T,  &I, &CURVE25519_2P);	// I = (qz * pt) % mod
			uop_calc(ADD, BANK_LO, PROC_I,    PROC_I,    BANK_HI, PROC_C, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_add( &I,  &I,  &C, &CURVE25519_2P);	// C = ( I +  I) % mod
			uop_calc(MUL, BANK_HI, CYCLE_S_T, CYCLE_V_Z, BANK_LO, PROC_I, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_mul(S_T, V_Z,  &I, &CURVE25519_2P);	// I = (qt * pz) % mod
			uop_calc(ADD, BANK_LO, PROC_I,    PROC_I,    BANK_HI, PROC_D, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_add( &I,  &I,  &D, &CURVE25519_2P);	// D = ( I + I) % mod

			uop_calc(ADD, BANK_HI, PROC_C,    PROC_D,    BANK_LO, PROC_E, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_add( &D,  &C,  &E, &CURVE25519_2P);	// E = (D + C) % mod
			uop_calc(SUB, BANK_HI, PROC_B,    PROC_A,    BANK_LO, PROC_F, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_sub( &B,  &A,  &F, &CURVE25519_2P);	// F = (B - A) % mod
			uop_calc(ADD, BANK_HI, PROC_B,    PROC_A,    BANK_LO, PROC_G, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_add( &B,  &A,  &G, &CURVE25519_2P);	// G = (B + A) % mod
			uop_calc(SUB, BANK_HI, PROC_D,    PROC_C,    BANK_LO, PROC_H, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_sub( &D,  &C,  &H, &CURVE25519_2P);	// H = (D - C) % mod

			uop_calc(MUL, BANK_LO, PROC_E,    PROC_F,    BANK_HI, CYCLE_T_X, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_mul( &E,  &F, R_X, &CURVE25519_2P);	// rx = (E * F) % mod
			uop_calc(MUL, BANK_LO, PROC_G,    PROC_H,    BANK_HI, CYCLE_T_Y, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_mul( &G,  &H, R_Y, &CURVE25519_2P);	// ry = (G * H) % mod
			uop_calc(MUL, BANK_LO, PROC_E,    PROC_H,    BANK_HI, CYCLE_T_T, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_mul( &E,  &H, R_T, &CURVE25519_2P);	// rt = (E * H) % mod
			uop_calc(MUL, BANK_LO, PROC_F,    PROC_G,    BANK_HI, CYCLE_T_Z, BUF_LO, BUF_HI,  MOD_2P);	//fpga_modular_mul( &F,  &G, R_Z, &CURVE25519_2P);	// rz = (F * G) % mod	
			
			if (k_bit)
			{
				// R0 = T

				uop_move2(BANK_HI, CYCLE_T_X, CYCLE_T_Y, BANK_LO, CYCLE_R0_X, CYCLE_R0_Y, BUF_LO, BUF_HI);
				uop_move2(BANK_HI, CYCLE_T_Z, CYCLE_T_T, BANK_LO, CYCLE_R0_Z, CYCLE_R0_T, BUF_LO, BUF_HI);
			}
			else
			{
				// R1 = T

				uop_move2(BANK_HI, CYCLE_T_X, CYCLE_T_Y, BANK_LO, CYCLE_R1_X, CYCLE_R1_Y, BUF_LO, BUF_HI);
				uop_move2(BANK_HI, CYCLE_T_Z, CYCLE_T_T, BANK_LO, CYCLE_R1_Z, CYCLE_R1_T, BUF_LO, BUF_HI);
			}
		}
	}

		// inversion expects result to be in LO: T1
	uop_move2(BANK_LO, CYCLE_R0_Z, CYCLE_R0_Z, BANK_HI, CYCLE_R0_Z, CYCLE_R0_Z, BUF_LO, BUF_HI);	
	uop_move2(BANK_HI, CYCLE_R0_Z, CYCLE_R0_Z, BANK_LO, INVERT_T_1, INVERT_T_1, BUF_LO, BUF_HI);	

		// just call piece of microcode
	fpga_modular_inv_microcode(BUF_LO, BUF_HI);

		// inversion places result in HI: R1
		// coordinates are in HI: R0_X, R0_Y

	uop_move2(BANK_HI, INVERT_R1, INVERT_R1, BANK_LO, INVERT_R1, INVERT_R1, BUF_LO, BUF_HI);
	uop_calc(MUL, BANK_LO, INVERT_R1, CYCLE_R0_X, BANK_HI, CYCLE_R0_X, BUF_LO, BUF_HI, MOD_2P);
	uop_calc(MUL, BANK_LO, INVERT_R1, CYCLE_R0_Y, BANK_HI, CYCLE_R0_Y, BUF_LO, BUF_HI, MOD_2P);

		// finally reduce to just 1*P
	uop_calc(ADD, BANK_HI, CYCLE_R0_X, CONST_ZERO, BANK_LO, CYCLE_R0_X, BUF_LO, BUF_HI, MOD_1P);	// !!!
	uop_calc(ADD, BANK_HI, CYCLE_R0_Y, CONST_ZERO, BANK_LO, CYCLE_R0_Y, BUF_LO, BUF_HI, MOD_1P);	// !!!

		// poke sign bit
	BUF_LO[CYCLE_R0_Y].words[FPGA_OPERAND_NUM_WORDS-1] |=
		(FPGA_WORD)((BUF_LO[CYCLE_R0_X].words[0] & (FPGA_WORD)1) << 31);

		// store result
	uop_stor(BUF_LO, BUF_HI, BANK_LO, CYCLE_R0_Y, QY);



	/*
		// process "sign" of x, see this Cryptography Stack Exchange
		// answer for more details:
		//
		// https://crypto.stackexchange.com/questions/58921/decoding-a-ed25519-key-per-rfc8032
		//
		// the short story is that odd values of x are negative, so we
		// just copy the lsb of x into msb of y
	R0_Y.words[FPGA_OPERAND_NUM_WORDS-1] |= (R0_X.words[0] & (FPGA_WORD)1) << 31;

		// store result
	fpga_multiword_copy(&R0_Y, QY);
	*/
}


//------------------------------------------------------------------------------
// End-of-File
//------------------------------------------------------------------------------