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-----------------------------------------------------------------------
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---- ----
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---- Montgomery modular multiplier and exponentiator ----
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---- ----
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---- This file is part of the Montgomery modular multiplier ----
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---- and exponentiator project ----
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---- http://opencores.org/project,mod_mult_exp ----
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---- ----
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---- Description: ----
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---- Montgomery modular multiplier main module. It combines all ----
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---- subomponents. It takes two numbers and modulus as the input ----
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---- and returns the Montgomery product A*B*(R^{-1}) mod M ----
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---- where R^{-1} is the modular multiplicative inverse. ----
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---- R*R^{-1} == 1 mod M ----
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---- R = 2^word_length mod M ----
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---- and word_length is the binary width of the ----
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---- operated word (in this case 32, 64 or 512 bit) ----
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---- To Do: ----
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---- ----
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---- Author(s): ----
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---- - Krzysztof Gajewski, gajos@opencores.org ----
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---- k.gajewski@gmail.com ----
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---- ----
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-----------------------------------------------------------------------
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---- ----
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---- Copyright (C) 2019 Authors and OPENCORES.ORG ----
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---- ----
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---- This source file may be used and distributed without ----
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---- restriction provided that this copyright statement is not ----
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---- removed from the file and that any derivative work contains ----
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---- the original copyright notice and the associated disclaimer. ----
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---- ----
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---- This source file is free software; you can redistribute it ----
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---- and-or modify it under the terms of the GNU Lesser General ----
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---- Public License as published by the Free Software Foundation; ----
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---- either version 2.1 of the License, or (at your option) any ----
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---- later version. ----
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---- ----
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---- This source is distributed in the hope that it will be ----
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---- useful, but WITHOUT ANY WARRANTY; without even the implied ----
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---- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ----
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---- PURPOSE. See the GNU Lesser General Public License for more ----
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---- details. ----
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---- ----
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---- You should have received a copy of the GNU Lesser General ----
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---- Public License along with this source; if not, download it ----
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---- from http://www.opencores.org/lgpl.shtml ----
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---- ----
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-----------------------------------------------------------------------
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library IEEE;
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use IEEE.STD_LOGIC_1164.ALL;
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use IEEE.STD_LOGIC_UNSIGNED.ALL;
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use IEEE.NUMERIC_STD.ALL;
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use work.properties.ALL;
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-- Uncomment the following library declaration if using
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-- arithmetic functions with Signed or Unsigned values
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--use IEEE.NUMERIC_STD.ALL;
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-- Uncomment the following library declaration if instantiating
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-- any Xilinx primitives in this code.
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--library UNISIM;
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--use UNISIM.VComponents.all;
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entity ModularMultiplierIterative is
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generic (
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word_size : integer := WORD_LENGTH
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);
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port (
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A : in STD_LOGIC_VECTOR(word_size - 1 downto 0); -- multiplicand
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B : in STD_LOGIC_VECTOR(word_size - 1 downto 0); -- multiplier
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M : in STD_LOGIC_VECTOR(word_size - 1 downto 0); -- modulus
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start : in STD_LOGIC;
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product : out STD_LOGIC_VECTOR(word_size - 1 downto 0); -- product
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ready : out STD_LOGIC;
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clk : in STD_LOGIC
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);
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end ModularMultiplierIterative;
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architecture Behavioral of ModularMultiplierIterative is
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-- Multiplexer
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component MontMult4inMux is
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generic (
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word_size : integer := WORD_LENGTH
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);
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port (
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ctrl : in STD_LOGIC_VECTOR(1 downto 0);
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zero : in STD_LOGIC_VECTOR(word_size downto 0);
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M : in STD_LOGIC_VECTOR(word_size downto 0);
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Y : in STD_LOGIC_VECTOR(word_size downto 0);
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YplusM : in STD_LOGIC_VECTOR(word_size downto 0);
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output : out STD_LOGIC_VECTOR(word_size downto 0)
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);
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end component MontMult4inMux;
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-- State machine
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component ModMultIter_SM is
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generic (
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word_size : integer := WORD_LENGTH
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);
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port(
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x : in STD_LOGIC_VECTOR(word_size - 1 downto 0);
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start : in STD_LOGIC;
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clk : in STD_LOGIC;
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s_0 : in STD_LOGIC;
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y_0 : in STD_LOGIC;
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ready : out STD_LOGIC;
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out_reg_en : out STD_LOGIC;
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mux_mult_ctrl : out STD_LOGIC;
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mux_4in_ctrl : out STD_LOGIC_VECTOR(1 downto 0)
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);
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end component ModMultIter_SM;
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-- Signals
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signal Mi : STD_LOGIC_VECTOR(word_size downto 0);
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signal Yi : STD_LOGIC_VECTOR(word_size downto 0);
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signal sumYM : STD_LOGIC_VECTOR(word_size downto 0);
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signal zero_sig : STD_LOGIC_VECTOR(word_size downto 0) := (others => '0');
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signal four_in_mux_out : STD_LOGIC_VECTOR(word_size downto 0);
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signal mux_4in_ctrl_sig : STD_LOGIC_VECTOR(1 downto 0);
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signal mult_mux_ctrl_sig : STD_LOGIC;
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signal mult_mux_out : STD_LOGIC_VECTOR(word_size downto 0);
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signal out_reg_sig : STD_LOGIC_VECTOR(word_size downto 0);
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signal product_sig : STD_LOGIC_VECTOR(word_size downto 0);
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signal out_en : STD_LOGIC;
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signal sum_mult_out : STD_LOGIC_VECTOR(word_size + 1 downto 0);
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signal sum_div_2 : STD_LOGIC_VECTOR(word_size downto 0);
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begin
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zero_sig <= (others => '0'); -- '0'
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-- 'widening' to store the intermediate steps
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Mi <= '0' & M;
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Yi <= '0' & B;
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-- Operations needed to compute the Montgomery multiplications
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sum_div_2 <= sum_mult_out(word_size + 1 downto 1);
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sum_mult_out <= ('0' & four_in_mux_out) + ('0' & mult_mux_out);
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sumYM <= ('0' & B) + ('0' & M);
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-- Multiplexer component
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four_in_mux : MontMult4inMux port map(
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ctrl => mux_4in_ctrl_sig, zero => zero_sig, M => Mi, Y => Yi,
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YplusM => sumYM, output => four_in_mux_out
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);
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-- Two input asynchronuos multiplexer for output 'not clear' code due to
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-- 'historical works'
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mult_mux_out <= (others => '0') when (mult_mux_ctrl_sig = '0') else
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out_reg_sig;
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-- State machine
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state_machine : ModMultIter_SM port map(
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x => A,
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start => start,
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clk => clk,
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s_0 => out_reg_sig(0),
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y_0 => B(0),
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ready => ready,
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out_reg_en => out_en,
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mux_mult_ctrl => mult_mux_ctrl_sig,
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mux_4in_ctrl => mux_4in_ctrl_sig
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);
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-- Register like structure for signal synchronous work
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clock : process(clk, start)
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begin
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if (clk = '1' and clk'Event) then
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if (start = '0') then
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out_reg_sig <= (others => '0');
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elsif out_en = '1' then
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out_reg_sig <= sum_div_2;
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end if;
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end if;
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end process clock;
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-- One additional 'subtract' component which was added after
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-- first experiments with Montgomery multiplication. It was
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-- observed that sometimes intermediate step can be higher
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-- than modulus. In this situation 'M' substraction is
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-- compulsory
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product_proc : process(clk, Mi, out_reg_sig)
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begin
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if(out_reg_sig < ("0" & Mi)) then
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product_sig <= out_reg_sig;
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else
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product_sig <= out_reg_sig - Mi;
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end if;
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end process product_proc;
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product <= product_sig(word_size - 1 downto 0);
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end Behavioral;
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