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eucrypt_ch6_kecca...    1  -- S.MG, 2018
eucrypt_ch9_kecca... 2 with System; use System; -- for Bit_Order
eucrypt_ch6_kecca... 3
eucrypt_ch6_kecca... 4 package body SMG_Keccak is
eucrypt_ch6_kecca... 5
eucrypt_ch7_kecca... 6 -- public function, sponge
eucrypt_ch7_kecca... 7 procedure Sponge( Input : in Bitstream;
eucrypt_ch7_kecca... 8 Block_Len : in Keccak_Rate;
eucrypt_ch7_kecca... 9 Output : out Bitstream) is
eucrypt_ch7_kecca... 10 Internal : State := (others => (others => 0));
eucrypt_ch7_kecca... 11 begin
eucrypt_ch7_kecca... 12 --absorb input into sponge in a loop on available blocks, including padding
eucrypt_ch7_kecca... 13 declare
eucrypt_ch7_kecca... 14 -- number of input blocks after padding (between 2 and block_len bits pad)
eucrypt_ch7_kecca... 15 Padded_Blocks : constant Positive := 1 + (Input'Length + 1) / Block_Len;
eucrypt_ch7_kecca... 16 Padded : Bitstream ( 1 .. Padded_Blocks * Block_Len );
eucrypt_ch7_kecca... 17 Block : Bitstream ( 1 .. Block_Len );
eucrypt_ch7_kecca... 18 begin
eucrypt_ch7_kecca... 19 -- initialise Padded with 0 everywhere
eucrypt_ch7_kecca... 20 Padded := ( others => 0 );
eucrypt_ch7_kecca... 21 -- copy and pad input with rule 10*1
eucrypt_ch7_kecca... 22 Padded( Padded'First .. Padded'First + Input'Length - 1 ) := Input;
eucrypt_ch7_kecca... 23 Padded( Padded'First + Input'Length ) := 1;
eucrypt_ch7_kecca... 24 Padded( Padded'Last ) := 1;
eucrypt_ch7_kecca... 25
eucrypt_ch7_kecca... 26 -- loop through padded input and absorb block by block into sponge
eucrypt_ch7_kecca... 27 -- padded input IS a multiple of blocks, so no stray bits left
eucrypt_ch7_kecca... 28 for B in 0 .. Padded_Blocks - 1 loop
eucrypt_ch7_kecca... 29 -- first get the current block to absorb
eucrypt_ch7_kecca... 30 Block := Padded( Padded'First + B * Block_Len ..
eucrypt_ch7_kecca... 31 Padded'First + (B+1) * Block_Len - 1 );
eucrypt_ch7_kecca... 32 AbsorbBlock( Block, Internal );
eucrypt_ch7_kecca... 33 -- scramble state with Keccak function
eucrypt_ch7_kecca... 34 Internal := Keccak_Function( Internal );
eucrypt_ch7_kecca... 35
eucrypt_ch7_kecca... 36 end loop; -- end absorb loop for blocks
eucrypt_ch7_kecca... 37 end; -- end absorb stage
eucrypt_ch7_kecca... 38
eucrypt_ch7_kecca... 39 --squeeze required bits from sponge in a loop as needed
eucrypt_ch7_kecca... 40 declare
eucrypt_ch7_kecca... 41 -- full blocks per output
eucrypt_ch7_kecca... 42 BPO : constant Natural := Output'Length / Block_Len;
eucrypt_ch7_kecca... 43 -- stray bits per output
eucrypt_ch7_kecca... 44 SPO : constant Natural := Output'Length mod Block_Len;
eucrypt_ch7_kecca... 45 Block : Bitstream( 1 .. Block_Len );
eucrypt_ch7_kecca... 46 begin
eucrypt_ch7_kecca... 47 -- squeeze block by block (if at least one full block is needed)
eucrypt_ch7_kecca... 48 for I in 0 .. BPO - 1 loop
eucrypt_ch7_kecca... 49 SqueezeBlock( Block, Internal );
eucrypt_ch7_kecca... 50 Output( Output'First + I * Block_Len ..
eucrypt_ch7_kecca... 51 Output'First + (I + 1) * Block_Len -1) := Block;
eucrypt_ch7_kecca... 52
eucrypt_ch7_kecca... 53 -- scramble state
eucrypt_ch7_kecca... 54 Internal := Keccak_Function( Internal );
eucrypt_ch7_kecca... 55 end loop; -- end squeezing full blocks
eucrypt_ch7_kecca... 56
eucrypt_ch7_kecca... 57 -- squeeze any partial block needed (stray bits)
eucrypt_ch7_kecca... 58 if SPO > 0 then
eucrypt_ch7_kecca... 59 SqueezeBlock( Block, Internal );
eucrypt_ch7_kecca... 60 Output( Output'Last - SPO + 1 .. Output'Last ) :=
eucrypt_ch7_kecca... 61 Block( Block'First .. Block'First + SPO - 1 );
eucrypt_ch7_kecca... 62 end if; -- end squeezing partial last block (stray bits)
eucrypt_ch7_kecca... 63
eucrypt_ch7_kecca... 64 end; -- end squeeze stage
eucrypt_ch7_kecca... 65 end Sponge;
eucrypt_ch7_kecca... 66
eucrypt_ch7_kecca... 67 -- convert from a bitstream of ZWord size to an actual ZWord number
eucrypt_ch9_kecca... 68 function BitsToWord( BWord: in Bitword ) return ZWord is
eucrypt_ch9_kecca... 69 W : ZWord;
eucrypt_ch9_kecca... 70 Bits: Bitword;
eucrypt_ch7_kecca... 71 begin
eucrypt_ch9_kecca... 72 -- just copy octets if machine is little endian
eucrypt_ch9_kecca... 73 -- flip octets if machine is big endian
eucrypt_ch9_kecca... 74 if Default_Bit_Order = Low_Order_First then
eucrypt_ch9_kecca... 75 Bits := BWord;
eucrypt_ch9_kecca... 76 else
eucrypt_ch9_kecca... 77 Bits := FlipOctets( BWord );
eucrypt_ch9_kecca... 78 end if;
eucrypt_ch9_kecca... 79 -- actual bits to word conversion
eucrypt_ch7_kecca... 80 W := 0;
eucrypt_ch9_kecca... 81 -- LSB bit order (inside octet) as per Keccak spec
eucrypt_ch7_kecca... 82 for I in reverse Bitword'Range loop
eucrypt_ch9_kecca... 83 W := Shift_Left( W, 1 ) + ZWord( Bits( I ) );
eucrypt_ch7_kecca... 84 end loop;
eucrypt_ch7_kecca... 85 return W;
eucrypt_ch7_kecca... 86 end BitsToWord;
eucrypt_ch7_kecca... 87
eucrypt_ch7_kecca... 88 -- convert from a ZWord (lane of state) to a bitstream of ZWord size
eucrypt_ch7_kecca... 89 function WordToBits( Word: in ZWord ) return Bitword is
eucrypt_ch7_kecca... 90 Bits: Bitword := (others => 0);
eucrypt_ch7_kecca... 91 W: ZWord;
eucrypt_ch7_kecca... 92 begin
eucrypt_ch7_kecca... 93 W := Word;
eucrypt_ch9_kecca... 94 for I in Bitword'Range loop
eucrypt_ch7_kecca... 95 Bits( I ) := Bit( W mod 2 );
eucrypt_ch9_kecca... 96 W := Shift_Right( W, 1 );
eucrypt_ch7_kecca... 97 end loop;
eucrypt_ch9_kecca... 98
eucrypt_ch9_kecca... 99 -- flip octets if machine is big endian
eucrypt_ch9_kecca... 100 if Default_Bit_Order = High_Order_First then
eucrypt_ch9_kecca... 101 Bits := FlipOctets( Bits );
eucrypt_ch9_kecca... 102 end if;
eucrypt_ch9_kecca... 103
eucrypt_ch7_kecca... 104 return Bits;
eucrypt_ch7_kecca... 105 end WordToBits;
eucrypt_ch7_kecca... 106
eucrypt_ch9_kecca... 107 -- flip given octets (i.e. groups of 8 bits)
eucrypt_ch9_kecca... 108 function FlipOctets( BWord : in Bitword ) return Bitword is
eucrypt_ch9_kecca... 109 Bits : Bitword;
eucrypt_ch9_kecca... 110 begin
eucrypt_ch9_kecca... 111 -- copy groups of 8 octets changing their order in the array
eucrypt_ch9_kecca... 112 -- i.e. 1st octet in BWord becomes last octet in Bits and so on
eucrypt_ch9_kecca... 113 for I in 0 .. ( Bitword'Length / 8 - 1 ) loop
eucrypt_ch9_kecca... 114 Bits ( Bits'First + I * 8 .. Bits'First + I * 8 + 7 ) :=
eucrypt_ch9_kecca... 115 BWord( BWord'Last - I * 8 - 7 .. BWord'Last - I * 8);
eucrypt_ch9_kecca... 116 end loop;
eucrypt_ch9_kecca... 117 return Bits;
eucrypt_ch9_kecca... 118 end FlipOctets;
eucrypt_ch9_kecca... 119
eucrypt_ch7_kecca... 120 -- helper procedures for sponge absorb/squeeze
eucrypt_ch7_kecca... 121
eucrypt_ch7_kecca... 122 -- NO scramble here, this will absorb ALL given block, make sure it fits!
eucrypt_ch7_kecca... 123 procedure AbsorbBlock( Block: in Bitstream; S: in out State ) is
eucrypt_ch7_kecca... 124 WPB: constant Natural := Block'Length / Z_Length; -- words per block
eucrypt_ch7_kecca... 125 SBB: constant Natural := Block'Length mod Z_Length; -- stray bits
eucrypt_ch7_kecca... 126 FromPos, ToPos : Natural;
eucrypt_ch7_kecca... 127 X, Y : XYCoord;
eucrypt_ch7_kecca... 128 Word : ZWord;
eucrypt_ch7_kecca... 129 BWord : Bitword;
eucrypt_ch7_kecca... 130 begin
eucrypt_ch7_kecca... 131 -- xor current block into first Block'Length bits of state
eucrypt_ch7_kecca... 132 -- a block can consist in more than one word
eucrypt_ch7_kecca... 133 X := 0;
eucrypt_ch7_kecca... 134 Y := 0;
eucrypt_ch7_kecca... 135 for I in 0..WPB-1 loop
eucrypt_ch7_kecca... 136 FromPos := Block'First + I * Z_Length;
eucrypt_ch7_kecca... 137 ToPos := FromPos + Z_Length - 1;
eucrypt_ch7_kecca... 138 Word := BitsToWord( Block( FromPos .. ToPos ) );
eucrypt_ch7_kecca... 139 S( X, Y ) := S( X, Y ) xor Word;
eucrypt_ch7_kecca... 140 -- move on to next word in state
eucrypt_ch7_kecca... 141 X := X + 1;
eucrypt_ch7_kecca... 142 if X = 0 then
eucrypt_ch7_kecca... 143 Y := Y + 1;
eucrypt_ch7_kecca... 144 end if;
eucrypt_ch7_kecca... 145 end loop;
eucrypt_ch7_kecca... 146 -- absorb also any remaining bits from block
eucrypt_ch7_kecca... 147 if SBB > 0 then
eucrypt_ch7_kecca... 148 ToPos := Block'Last;
eucrypt_ch7_kecca... 149 FromPos := ToPos - SBB + 1;
eucrypt_ch7_kecca... 150 BWord := (others => 0);
eucrypt_ch7_kecca... 151 BWord(Bitword'First .. Bitword'First + SBB - 1) := Block(ToPos..FromPos);
eucrypt_ch7_kecca... 152 Word := BitsToWord( BWord );
eucrypt_ch7_kecca... 153 S( X, Y ) := S( X, Y ) xor Word;
eucrypt_ch7_kecca... 154 end if;
eucrypt_ch7_kecca... 155 end AbsorbBlock;
eucrypt_ch7_kecca... 156
eucrypt_ch7_kecca... 157 -- NO scramble here, this will squeeze Block'Length bits out of *same* state S
eucrypt_ch7_kecca... 158 procedure SqueezeBlock( Block: out Bitstream; S: in State) is
eucrypt_ch7_kecca... 159 X, Y : XYCoord;
eucrypt_ch7_kecca... 160 BWord : Bitword;
eucrypt_ch7_kecca... 161 FromPos : Natural;
eucrypt_ch7_kecca... 162 Len : Natural;
eucrypt_ch7_kecca... 163 begin
eucrypt_ch7_kecca... 164 X := 0;
eucrypt_ch7_kecca... 165 Y := 0;
eucrypt_ch7_kecca... 166 FromPos := Block'First;
eucrypt_ch7_kecca... 167
eucrypt_ch7_kecca... 168 while FromPos <= Block'Last loop
eucrypt_ch7_kecca... 169 BWord := WordToBits( S(X, Y) );
eucrypt_ch7_kecca... 170
eucrypt_ch7_kecca... 171 X := X + 1;
eucrypt_ch7_kecca... 172 if X = 0 then
eucrypt_ch7_kecca... 173 Y := Y + 1;
eucrypt_ch7_kecca... 174 end if;
eucrypt_ch7_kecca... 175
eucrypt_ch7_kecca... 176 -- copy full word if it fits or
eucrypt_ch7_kecca... 177 -- only as many bits as are still needed to fill the block
eucrypt_ch7_kecca... 178 Len := Block'Last - FromPos + 1;
eucrypt_ch7_kecca... 179 if Len > Z_Length then
eucrypt_ch7_kecca... 180 Len := Z_Length;
eucrypt_ch7_kecca... 181 end if;
eucrypt_ch7_kecca... 182
eucrypt_ch7_kecca... 183 Block(FromPos..FromPos+Len-1) := BWord(BWord'First..BWord'First+Len-1);
eucrypt_ch7_kecca... 184 FromPos := FromPos + Len;
eucrypt_ch7_kecca... 185 end loop;
eucrypt_ch7_kecca... 186 end SqueezeBlock;
eucrypt_ch7_kecca... 187
eucrypt_ch7_kecca... 188
eucrypt_ch7_kecca... 189 -- private, internal transformations
eucrypt_ch6_kecca... 190 function Theta(Input : in State) return State is
eucrypt_ch6_kecca... 191 Output : State;
eucrypt_ch6_kecca... 192 C : Plane;
eucrypt_ch6_kecca... 193 W : ZWord;
eucrypt_ch6_kecca... 194 begin
eucrypt_ch6_kecca... 195 for X in XYCoord loop
eucrypt_ch6_kecca... 196 C(X) := Input(X, 0);
eucrypt_ch6_kecca... 197 for Y in 1..XYCoord'Last loop
eucrypt_ch6_kecca... 198 C(X) := C(X) xor Input(X, Y);
eucrypt_ch6_kecca... 199 end loop;
eucrypt_ch6_kecca... 200 end loop;
eucrypt_ch6_kecca... 201
eucrypt_ch6_kecca... 202 for X in XYCoord loop
eucrypt_ch6_kecca... 203 W := C(X-1) xor Rotate_Left(C(X+1), 1);
eucrypt_ch6_kecca... 204 for Y in XYCoord loop
eucrypt_ch6_kecca... 205 Output(X,Y) := Input(X,Y) xor W;
eucrypt_ch6_kecca... 206 end loop;
eucrypt_ch6_kecca... 207 end loop;
eucrypt_ch6_kecca... 208
eucrypt_ch6_kecca... 209 return Output;
eucrypt_ch6_kecca... 210 end Theta;
eucrypt_ch6_kecca... 211
eucrypt_ch6_kecca... 212 function Rho(Input : in State) return State is
eucrypt_ch6_kecca... 213 Output : State;
eucrypt_ch6_kecca... 214 X, Y, Old_Y : XYCoord;
eucrypt_ch6_kecca... 215 begin
eucrypt_ch6_kecca... 216 Output(0,0) := Input(0,0);
eucrypt_ch6_kecca... 217 X := 1;
eucrypt_ch6_kecca... 218 Y := 0;
eucrypt_ch6_kecca... 219
eucrypt_ch6_kecca... 220 for T in 0..23 loop
eucrypt_ch6_kecca... 221 Output(X, Y) := Rotate_Left(Input(X,Y), ((T+1)*(T+2)/2) mod Z_Length);
eucrypt_ch6_kecca... 222 Old_Y := Y;
eucrypt_ch6_kecca... 223 Y := 2*X + 3*Y;
eucrypt_ch6_kecca... 224 X := Old_Y;
eucrypt_ch6_kecca... 225 end loop;
eucrypt_ch6_kecca... 226 return Output;
eucrypt_ch6_kecca... 227 end rho;
eucrypt_ch6_kecca... 228
eucrypt_ch6_kecca... 229 function Pi(Input : in State) return State is
eucrypt_ch6_kecca... 230 Output: State;
eucrypt_ch6_kecca... 231 begin
eucrypt_ch6_kecca... 232 for X in XYCoord loop
eucrypt_ch6_kecca... 233 for Y in XYCoord loop
eucrypt_ch6_kecca... 234 Output(Y, 2*X + 3*Y) := Input(X, Y);
eucrypt_ch6_kecca... 235 end loop;
eucrypt_ch6_kecca... 236 end loop;
eucrypt_ch6_kecca... 237 return Output;
eucrypt_ch6_kecca... 238 end pi;
eucrypt_ch6_kecca... 239
eucrypt_ch6_kecca... 240 function Chi(Input : in State) return State is
eucrypt_ch6_kecca... 241 Output: State;
eucrypt_ch6_kecca... 242 begin
eucrypt_ch6_kecca... 243 for Y in XYCoord loop
eucrypt_ch6_kecca... 244 for X in XYCoord loop
eucrypt_ch6_kecca... 245 Output(X, Y) := Input(X, Y) xor
eucrypt_ch6_kecca... 246 ( (not Input(X + 1, Y)) and Input(X + 2, Y) );
eucrypt_ch6_kecca... 247 end loop;
eucrypt_ch6_kecca... 248 end loop;
eucrypt_ch6_kecca... 249 return Output;
eucrypt_ch6_kecca... 250 end chi;
eucrypt_ch6_kecca... 251
eucrypt_ch6_kecca... 252 function Iota(Round_Const : in ZWord; Input : in State) return State is
eucrypt_ch6_kecca... 253 Output: State;
eucrypt_ch6_kecca... 254 begin
eucrypt_ch6_kecca... 255 Output := Input;
eucrypt_ch6_kecca... 256 Output(0,0) := Input(0,0) xor Round_Const;
eucrypt_ch6_kecca... 257 return Output;
eucrypt_ch6_kecca... 258 end iota;
eucrypt_ch6_kecca... 259
eucrypt_ch6_kecca... 260 function Keccak_Function(Input: in State) return State is
eucrypt_ch6_kecca... 261 Output: State;
eucrypt_ch6_kecca... 262 begin
eucrypt_ch6_kecca... 263 Output := Input;
eucrypt_ch6_kecca... 264 for I in Round_Index loop
eucrypt_ch6_kecca... 265 Output := Iota(RC(I), Chi(Pi(Rho(Theta(Output)))));
eucrypt_ch6_kecca... 266 end loop;
eucrypt_ch6_kecca... 267
eucrypt_ch6_kecca... 268 return Output;
eucrypt_ch6_kecca... 269 end Keccak_Function;
eucrypt_ch6_kecca... 270
eucrypt_ch6_kecca... 271 end SMG_Keccak;