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-----------------------------------------------------------------------
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---- ----
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---- Present - a lightweight block cipher project ----
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---- ----
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---- This file is part of the Present - a lightweight block ----
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---- cipher project ----
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---- http://www.http://opencores.org/project,present ----
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---- ----
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---- Description: ----
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---- Inverse Key update module for present cipher decoding ----
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---- it is 'signal mixing' made by rotation right by 61 bits, ----
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---- using one s-box, and output of the counter. Note, that order ----
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---- of this operatins must be inverse in comparison with key_upd. ----
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---- For more information see ----
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---- http://homes.esat.kuleuven.be/~abogdano/papers/ ----
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---- present_ches07.pdf ----
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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) 2013 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_ARITH.ALL;
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use IEEE.STD_LOGIC_UNSIGNED.ALL;
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entity keyupd_inv is
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generic(
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w_80: integer := 80;
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w_5 : integer := 5;
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w_4 : integer := 4);
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port(
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key : in std_logic_vector(w_80-1 downto 0);
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num : in std_logic_vector(w_5-1 downto 0);
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keyout : out std_logic_vector(w_80-1 downto 0)
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);
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end keyupd_inv;
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architecture Behavioral of keyupd_inv is
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component slayer_inv is
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generic(w_4: integer := 4);
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port(
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input : in std_logic_vector(w_4-1 downto 0);
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output : out std_logic_vector(w_4-1 downto 0)
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);
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end component;
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signal changed : std_logic_vector(w_4-1 downto 0);
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signal changin : std_logic_vector(w_4-1 downto 0);
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signal keytemp : std_logic_vector(w_80-1 downto 0);
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begin
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s1: slayer_inv port map(input => changin, output => changed);
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changin <= key(79 downto 76);
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keytemp(79 downto 76)<= changed;
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keytemp(75 downto 20) <= key(75 downto 20);
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keytemp(19 downto 15)<= key(19 downto 15) xor num;
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keytemp(14 downto 0) <= key(14 downto 0);
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keyout <= keytemp(60 downto 0) & keytemp(79 downto 61);
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end Behavioral;
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