| 1 |
13 |
serginhofr |
--XTEA encryption algorithm v0.3
|
| 2 |
|
|
--Sergio Johann Filho, 2016
|
| 3 |
|
|
--
|
| 4 |
|
|
--based on reference code (below) released into the public domain by David Wheeler and Roger Needham
|
| 5 |
|
|
--the code takes 64 bits of data in v[0] and v[1] and 128 bits of key in key[0] - key[3]
|
| 6 |
|
|
--recommended number of rounds is 32 (2 Feistel-network rounds are performed on each iteration).
|
| 7 |
|
|
--
|
| 8 |
|
|
--
|
| 9 |
|
|
--void encipher(uint32_t num_rounds, uint32_t v[2], uint32_t const key[4]){
|
| 10 |
|
|
-- uint32_t i;
|
| 11 |
|
|
-- uint32_t v0 = v[0], v1 = v[1], sum = 0, delta = 0x9E3779B9;
|
| 12 |
|
|
--
|
| 13 |
|
|
-- for (i = 0; i < num_rounds; i++){
|
| 14 |
|
|
-- v0 += (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + key[sum & 3]);
|
| 15 |
|
|
-- sum += delta;
|
| 16 |
|
|
-- v1 += (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + key[(sum>>11) & 3]);
|
| 17 |
|
|
-- }
|
| 18 |
|
|
-- v[0] = v0; v[1] = v1;
|
| 19 |
|
|
--}
|
| 20 |
|
|
--
|
| 21 |
|
|
--void decipher(uint32_t num_rounds, uint32_t v[2], uint32_t const key[4]){
|
| 22 |
|
|
-- uint32_t i;
|
| 23 |
|
|
-- uint32_t v0 = v[0], v1 = v[1], delta = 0x9E3779B9, sum = delta * num_rounds;
|
| 24 |
|
|
--
|
| 25 |
|
|
-- for (i = 0; i < num_rounds; i++){
|
| 26 |
|
|
-- v1 -= (((v0 << 4) ^ (v0 >> 5)) + v0) ^ (sum + key[(sum>>11) & 3]);
|
| 27 |
|
|
-- sum -= delta;
|
| 28 |
|
|
-- v0 -= (((v1 << 4) ^ (v1 >> 5)) + v1) ^ (sum + key[sum & 3]);
|
| 29 |
|
|
-- }
|
| 30 |
|
|
-- v[0] = v0; v[1] = v1;
|
| 31 |
|
|
--}
|
| 32 |
|
|
|
| 33 |
|
|
library ieee;
|
| 34 |
|
|
use ieee.std_logic_1164.all;
|
| 35 |
|
|
use ieee.std_logic_unsigned.all;
|
| 36 |
|
|
use ieee.std_logic_arith.all;
|
| 37 |
|
|
|
| 38 |
|
|
entity xtea is
|
| 39 |
|
|
generic (
|
| 40 |
|
|
ROUNDS: integer := 32
|
| 41 |
|
|
);
|
| 42 |
|
|
port ( clock: in std_logic;
|
| 43 |
|
|
reset: in std_logic;
|
| 44 |
|
|
start: in std_logic;
|
| 45 |
|
|
encrypt: in std_logic;
|
| 46 |
|
|
key: in std_logic_vector(127 downto 0);
|
| 47 |
|
|
input: in std_logic_vector(63 downto 0);
|
| 48 |
|
|
output: out std_logic_vector(63 downto 0);
|
| 49 |
|
|
ready: out std_logic
|
| 50 |
|
|
);
|
| 51 |
|
|
end xtea;
|
| 52 |
|
|
|
| 53 |
|
|
architecture xtea_arch of xtea is
|
| 54 |
|
|
type states is (idle, enc_step1, enc_step2, enc_step3, dec_step1, dec_step2, dec_step3, key_sel1, key_sel2, done);
|
| 55 |
|
|
signal state: states;
|
| 56 |
|
|
signal v0, v1, sum, delta, key_sel: std_logic_vector(31 downto 0);
|
| 57 |
|
|
signal counter: std_logic_vector(7 downto 0);
|
| 58 |
|
|
begin
|
| 59 |
|
|
|
| 60 |
|
|
delta <= x"9e3779b9";
|
| 61 |
|
|
|
| 62 |
|
|
process(clock, reset)
|
| 63 |
|
|
begin
|
| 64 |
|
|
if reset = '1' then
|
| 65 |
|
|
v0 <= (others => '0');
|
| 66 |
|
|
v1 <= (others => '0');
|
| 67 |
|
|
sum <= (others => '0');
|
| 68 |
|
|
key_sel <= (others => '0');
|
| 69 |
|
|
counter <= (others => '0');
|
| 70 |
|
|
output <= (others => '0');
|
| 71 |
|
|
ready <= '0';
|
| 72 |
|
|
elsif clock'event and clock = '1' then
|
| 73 |
|
|
case state is
|
| 74 |
|
|
when idle =>
|
| 75 |
|
|
ready <= '0';
|
| 76 |
|
|
counter <= (others => '0');
|
| 77 |
|
|
when key_sel1 =>
|
| 78 |
|
|
case sum(1 downto 0) is
|
| 79 |
|
|
when "00" =>
|
| 80 |
|
|
key_sel <= key(127 downto 96);
|
| 81 |
|
|
when "01" =>
|
| 82 |
|
|
key_sel <= key(95 downto 64);
|
| 83 |
|
|
when "10" =>
|
| 84 |
|
|
key_sel <= key(63 downto 32);
|
| 85 |
|
|
when "11" =>
|
| 86 |
|
|
key_sel <= key(31 downto 0);
|
| 87 |
|
|
when others => null;
|
| 88 |
|
|
end case;
|
| 89 |
|
|
when key_sel2 =>
|
| 90 |
|
|
case sum(12 downto 11) is
|
| 91 |
|
|
when "00" =>
|
| 92 |
|
|
key_sel <= key(127 downto 96);
|
| 93 |
|
|
when "01" =>
|
| 94 |
|
|
key_sel <= key(95 downto 64);
|
| 95 |
|
|
when "10" =>
|
| 96 |
|
|
key_sel <= key(63 downto 32);
|
| 97 |
|
|
when "11" =>
|
| 98 |
|
|
key_sel <= key(31 downto 0);
|
| 99 |
|
|
when others => null;
|
| 100 |
|
|
end case;
|
| 101 |
|
|
when enc_step1 =>
|
| 102 |
|
|
v1 <= input(31 downto 0);
|
| 103 |
|
|
v0 <= input(63 downto 32);
|
| 104 |
|
|
sum <= (others => '0');
|
| 105 |
|
|
when enc_step2 =>
|
| 106 |
|
|
v0 <= v0 + ((((v1(27 downto 0) & "0000") xor ("00000" & v1(31 downto 5))) + v1) xor (sum + key_sel));
|
| 107 |
|
|
sum <= sum + delta;
|
| 108 |
|
|
when enc_step3 =>
|
| 109 |
|
|
v1 <= v1 + ((((v0(27 downto 0) & "0000") xor ("00000" & v0(31 downto 5))) + v0) xor (sum + key_sel));
|
| 110 |
|
|
counter <= counter + 1;
|
| 111 |
|
|
when dec_step1 =>
|
| 112 |
|
|
v1 <= input(31 downto 0);
|
| 113 |
|
|
v0 <= input(63 downto 32);
|
| 114 |
|
|
sum <= x"c6ef3720";
|
| 115 |
|
|
when dec_step2 =>
|
| 116 |
|
|
v1 <= v1 - ((((v0(27 downto 0) & "0000") xor ("00000" & v0(31 downto 5))) + v0) xor (sum + key_sel));
|
| 117 |
|
|
sum <= sum - delta;
|
| 118 |
|
|
when dec_step3 =>
|
| 119 |
|
|
v0 <= v0 - ((((v1(27 downto 0) & "0000") xor ("00000" & v1(31 downto 5))) + v1) xor (sum + key_sel));
|
| 120 |
|
|
counter <= counter + 1;
|
| 121 |
|
|
when done =>
|
| 122 |
|
|
output(63 downto 32) <= v0;
|
| 123 |
|
|
output(31 downto 0) <= v1;
|
| 124 |
|
|
ready <= '1';
|
| 125 |
|
|
when others => null;
|
| 126 |
|
|
end case;
|
| 127 |
|
|
end if;
|
| 128 |
|
|
end process;
|
| 129 |
|
|
|
| 130 |
|
|
process(clock, reset, state, counter, start, encrypt)
|
| 131 |
|
|
begin
|
| 132 |
|
|
if reset = '1' then
|
| 133 |
|
|
state <= idle;
|
| 134 |
|
|
elsif clock'event and clock = '1' then
|
| 135 |
|
|
case state is
|
| 136 |
|
|
when idle =>
|
| 137 |
|
|
if (start = '1') then
|
| 138 |
|
|
if (encrypt = '1') then
|
| 139 |
|
|
state <= enc_step1;
|
| 140 |
|
|
else
|
| 141 |
|
|
state <= dec_step1;
|
| 142 |
|
|
end if;
|
| 143 |
|
|
else
|
| 144 |
|
|
state <= idle;
|
| 145 |
|
|
end if;
|
| 146 |
|
|
when key_sel1 =>
|
| 147 |
|
|
if (encrypt = '1') then
|
| 148 |
|
|
state <= enc_step2;
|
| 149 |
|
|
else
|
| 150 |
|
|
state <= dec_step3;
|
| 151 |
|
|
end if;
|
| 152 |
|
|
when key_sel2 =>
|
| 153 |
|
|
if (encrypt = '1') then
|
| 154 |
|
|
state <= enc_step3;
|
| 155 |
|
|
else
|
| 156 |
|
|
state <= dec_step2;
|
| 157 |
|
|
end if;
|
| 158 |
|
|
when enc_step1 => state <= key_sel1;
|
| 159 |
|
|
when enc_step2 => state <= key_sel2;
|
| 160 |
|
|
when enc_step3 =>
|
| 161 |
|
|
if (counter < ROUNDS-1) then
|
| 162 |
|
|
state <= key_sel1;
|
| 163 |
|
|
else
|
| 164 |
|
|
state <= done;
|
| 165 |
|
|
end if;
|
| 166 |
|
|
when dec_step1 => state <= key_sel2;
|
| 167 |
|
|
when dec_step2 => state <= key_sel1;
|
| 168 |
|
|
when dec_step3 =>
|
| 169 |
|
|
if (counter < ROUNDS-1) then
|
| 170 |
|
|
state <= key_sel2;
|
| 171 |
|
|
else
|
| 172 |
|
|
state <= done;
|
| 173 |
|
|
end if;
|
| 174 |
|
|
when done =>
|
| 175 |
|
|
if (start = '1') then
|
| 176 |
|
|
state <= done;
|
| 177 |
|
|
else
|
| 178 |
|
|
state <= idle;
|
| 179 |
|
|
end if;
|
| 180 |
|
|
when others => null;
|
| 181 |
|
|
end case;
|
| 182 |
|
|
end if;
|
| 183 |
|
|
end process;
|
| 184 |
|
|
|
| 185 |
|
|
end xtea_arch;
|
| 186 |
|
|
|
| 187 |
|
|
|
