eucrypt_ch16_bytestream

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eucrypt_ch11_serpent    1  -------------------------------------------------------------------------------
eucrypt_ch11_serpent    2  --
eucrypt_ch11_serpent    3  -- Serpent Blockcipher
eucrypt_ch11_serpent    4  --
eucrypt_ch11_serpent    5  -- Copyright (c) 1998 Markus G. Kuhn <mkuhn@acm.org>. All rights reserved.
eucrypt_ch11_serpent    6  --
eucrypt_ch11_serpent    7  -- Modified by S.MG, 2018
eucrypt_ch11_serpent    8  --
eucrypt_ch11_serpent    9  -------------------------------------------------------------------------------
eucrypt_ch11_serpent   10  --
eucrypt_ch11_serpent   11  -- This implementation is optimized for best execution time by use of
eucrypt_ch11_serpent   12  -- function inlining and loop unrolling. It is not intended to be used in
eucrypt_ch11_serpent   13  -- applications (such as smartcards) where machine code size matters. Best
eucrypt_ch11_serpent   14  -- compiled with highest optimization level activated and all run-time
eucrypt_ch11_serpent   15  -- checks supressed.
eucrypt_ch11_serpent   16  --
eucrypt_ch11_serpent   17  -------------------------------------------------------------------------------
eucrypt_ch11_serpent   18 
eucrypt_ch11_serpent   19 with System, Ada.Unchecked_Conversion;
eucrypt_ch11_serpent   20 use System;
eucrypt_ch11_serpent   21 
eucrypt_ch11_serpent   22 package body SMG_Serpent is
eucrypt_ch11_serpent   23 
eucrypt_ch11_serpent   24   pragma Optimize( Time );
eucrypt_ch11_serpent   25 
eucrypt_ch11_serpent   26   -- Auxiliary functions for byte array to word array conversion with
eucrypt_ch11_serpent   27   -- Bigendian/Littleendian handling.
eucrypt_ch11_serpent   28   --
eucrypt_ch11_serpent   29   -- The convention followed here is that the input byte array
eucrypt_ch11_serpent   30   -- 
eucrypt_ch11_serpent   31   --   00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
eucrypt_ch11_serpent   32   --
eucrypt_ch11_serpent   33   -- is converted into the register values
eucrypt_ch11_serpent   34   --
eucrypt_ch11_serpent   35   --   X0 = 03020100,  X1 = 07060504,  X2 = 0b0a0908,  X3 = 0f0e0d0c
eucrypt_ch11_serpent   36 
eucrypt_ch11_serpent   37   subtype Bytes_4 is Bytes (0 .. 3);
eucrypt_ch11_serpent   38   function Cast is new Ada.Unchecked_Conversion (Bytes_4, Unsigned_32);
eucrypt_ch11_serpent   39   function Cast is new Ada.Unchecked_Conversion (Unsigned_32, Bytes_4);
eucrypt_ch11_serpent   40 
eucrypt_ch11_serpent   41   function Bytes_To_Word (X : Bytes_4) return Unsigned_32 is
eucrypt_ch11_serpent   42   begin
eucrypt_ch11_serpent   43     if Default_Bit_Order = Low_Order_First then
eucrypt_ch11_serpent   44       -- we have a Littleendian processor
eucrypt_ch11_serpent   45       return Cast(X);
eucrypt_ch11_serpent   46     else
eucrypt_ch11_serpent   47       -- word sex change
eucrypt_ch11_serpent   48       return Cast((X(3), X(2), X(1), X(0)));
eucrypt_ch11_serpent   49     end if;
eucrypt_ch11_serpent   50   end Bytes_To_Word;
eucrypt_ch11_serpent   51    
eucrypt_ch11_serpent   52   function Word_To_Bytes (X : Unsigned_32) return Bytes_4 is
eucrypt_ch11_serpent   53   begin
eucrypt_ch11_serpent   54     if Default_Bit_Order = Low_Order_First then
eucrypt_ch11_serpent   55       -- we have a Littleendian processor
eucrypt_ch11_serpent   56       return Cast(X);
eucrypt_ch11_serpent   57     else
eucrypt_ch11_serpent   58       -- word sex change
eucrypt_ch11_serpent   59       return (Cast(X)(3), Cast(X)(2), Cast(X)(1), Cast(X)(0));
eucrypt_ch11_serpent   60     end if;
eucrypt_ch11_serpent   61   end Word_To_Bytes;
eucrypt_ch11_serpent   62 
eucrypt_ch11_serpent   63   pragma Inline(Bytes_To_Word, Word_To_Bytes);
eucrypt_ch11_serpent   64   -- inline functions for the Encryption and Decryption procedures
eucrypt_ch11_serpent   65 
eucrypt_ch11_serpent   66   -- Sbox function   
eucrypt_ch11_serpent   67   procedure S (R : Integer; X0, X1, X2, X3 : in out Unsigned_32) is
eucrypt_ch11_serpent   68       T01, T02, T03, T04, T05, T06, T07, T08, T09,
eucrypt_ch11_serpent   69       T10, T11, T12, T13, T14, T15, T16, T17, T18 : Unsigned_32;
eucrypt_ch11_serpent   70       W, X, Y, Z : Unsigned_32;
eucrypt_ch11_serpent   71   begin
eucrypt_ch11_serpent   72     if R = 0 then
eucrypt_ch11_serpent   73       -- S0:   3  8 15  1 10  6  5 11 14 13  4  2  7  0  9 12
eucrypt_ch11_serpent   74       -- depth = 5,7,4,2, Total gates=18
eucrypt_ch11_serpent   75       T01 := X1  xor X2;
eucrypt_ch11_serpent   76       T02 := X0  or X3;
eucrypt_ch11_serpent   77       T03 := X0  xor X1;
eucrypt_ch11_serpent   78       Z   := T02 xor T01;
eucrypt_ch11_serpent   79       T05 := X2  or z;
eucrypt_ch11_serpent   80       T06 := X0  xor X3; 
eucrypt_ch11_serpent   81       T07 := X1  or X2; 
eucrypt_ch11_serpent   82       T08 := X3  and T05; 
eucrypt_ch11_serpent   83       T09 := T03 and T07; 
eucrypt_ch11_serpent   84       Y   := T09 xor T08; 
eucrypt_ch11_serpent   85       T11 := T09 and y; 
eucrypt_ch11_serpent   86       T12 := X2  xor X3; 
eucrypt_ch11_serpent   87       T13 := T07 xor T11; 
eucrypt_ch11_serpent   88       T14 := X1  and T06; 
eucrypt_ch11_serpent   89       T15 := T06 xor T13; 
eucrypt_ch11_serpent   90       W   :=     not T15; 
eucrypt_ch11_serpent   91       T17 := W   xor T14; 
eucrypt_ch11_serpent   92       X   := T12 xor T17;
eucrypt_ch11_serpent   93     elsif R = 1 then
eucrypt_ch11_serpent   94       -- S1:  15 12  2  7  9  0  5 10  1 11 14  8  6 13  3  4
eucrypt_ch11_serpent   95       -- depth = 10,7,3,5, Total gates=18
eucrypt_ch11_serpent   96       T01 := X0  or X3; 
eucrypt_ch11_serpent   97       T02 := X2  xor X3; 
eucrypt_ch11_serpent   98       T03 :=     not X1; 
eucrypt_ch11_serpent   99       T04 := X0  xor X2; 
eucrypt_ch11_serpent  100       T05 := X0  or T03; 
eucrypt_ch11_serpent  101       T06 := X3  and T04; 
eucrypt_ch11_serpent  102       T07 := T01 and T02; 
eucrypt_ch11_serpent  103       T08 := X1  or T06; 
eucrypt_ch11_serpent  104       Y   := T02 xor T05; 
eucrypt_ch11_serpent  105       T10 := T07 xor T08; 
eucrypt_ch11_serpent  106       T11 := T01 xor T10; 
eucrypt_ch11_serpent  107       T12 := Y   xor T11; 
eucrypt_ch11_serpent  108       T13 := X1  and X3; 
eucrypt_ch11_serpent  109       Z   :=     not T10; 
eucrypt_ch11_serpent  110       X   := T13 xor T12; 
eucrypt_ch11_serpent  111       T16 := T10 or x; 
eucrypt_ch11_serpent  112       T17 := T05 and T16; 
eucrypt_ch11_serpent  113       W   := X2  xor T17;
eucrypt_ch11_serpent  114     elsif R = 2 then
eucrypt_ch11_serpent  115       -- S2:   8  6  7  9  3 12 10 15 13  1 14  4  0 11  5  2
eucrypt_ch11_serpent  116       -- depth = 3,8,11,7, Total gates=16
eucrypt_ch11_serpent  117       T01 := X0  or X2; 
eucrypt_ch11_serpent  118       T02 := X0  xor X1; 
eucrypt_ch11_serpent  119       T03 := X3  xor T01; 
eucrypt_ch11_serpent  120       W   := T02 xor T03; 
eucrypt_ch11_serpent  121       T05 := X2  xor w; 
eucrypt_ch11_serpent  122       T06 := X1  xor T05; 
eucrypt_ch11_serpent  123       T07 := X1  or T05; 
eucrypt_ch11_serpent  124       T08 := T01 and T06; 
eucrypt_ch11_serpent  125       T09 := T03 xor T07; 
eucrypt_ch11_serpent  126       T10 := T02 or T09; 
eucrypt_ch11_serpent  127       X   := T10 xor T08; 
eucrypt_ch11_serpent  128       T12 := X0  or X3; 
eucrypt_ch11_serpent  129       T13 := T09 xor x; 
eucrypt_ch11_serpent  130       T14 := X1  xor T13; 
eucrypt_ch11_serpent  131       Z   :=     not T09; 
eucrypt_ch11_serpent  132       Y   := T12 xor T14;
eucrypt_ch11_serpent  133     elsif R = 3 then
eucrypt_ch11_serpent  134       -- S3:   0 15 11  8 12  9  6  3 13  1  2  4 10  7  5 14
eucrypt_ch11_serpent  135       -- depth = 8,3,5,5, Total gates=18
eucrypt_ch11_serpent  136       T01 := X0  xor X2; 
eucrypt_ch11_serpent  137       T02 := X0  or X3; 
eucrypt_ch11_serpent  138       T03 := X0  and X3; 
eucrypt_ch11_serpent  139       T04 := T01 and T02; 
eucrypt_ch11_serpent  140       T05 := X1  or T03; 
eucrypt_ch11_serpent  141       T06 := X0  and X1; 
eucrypt_ch11_serpent  142       T07 := X3  xor T04; 
eucrypt_ch11_serpent  143       T08 := X2  or T06; 
eucrypt_ch11_serpent  144       T09 := X1  xor T07; 
eucrypt_ch11_serpent  145       T10 := X3  and T05; 
eucrypt_ch11_serpent  146       T11 := T02 xor T10; 
eucrypt_ch11_serpent  147       Z   := T08 xor T09; 
eucrypt_ch11_serpent  148       T13 := X3  or z; 
eucrypt_ch11_serpent  149       T14 := X0  or T07; 
eucrypt_ch11_serpent  150       T15 := X1  and T13; 
eucrypt_ch11_serpent  151       Y   := T08 xor T11; 
eucrypt_ch11_serpent  152       W   := T14 xor T15; 
eucrypt_ch11_serpent  153       X   := T05 xor T04;
eucrypt_ch11_serpent  154     elsif R = 4 then
eucrypt_ch11_serpent  155       -- S4:   1 15  8  3 12  0 11  6  2  5  4 10  9 14  7 13
eucrypt_ch11_serpent  156       -- depth = 6,7,5,3, Total gates=19
eucrypt_ch11_serpent  157       T01 := X0  or X1; 
eucrypt_ch11_serpent  158       T02 := X1  or X2; 
eucrypt_ch11_serpent  159       T03 := X0  xor T02; 
eucrypt_ch11_serpent  160       T04 := X1  xor X3; 
eucrypt_ch11_serpent  161       T05 := X3  or T03; 
eucrypt_ch11_serpent  162       T06 := X3  and T01; 
eucrypt_ch11_serpent  163       Z   := T03 xor T06; 
eucrypt_ch11_serpent  164       T08 := Z   and T04; 
eucrypt_ch11_serpent  165       T09 := T04 and T05; 
eucrypt_ch11_serpent  166       T10 := X2  xor T06; 
eucrypt_ch11_serpent  167       T11 := X1  and X2; 
eucrypt_ch11_serpent  168       T12 := T04 xor T08; 
eucrypt_ch11_serpent  169       T13 := T11 or T03; 
eucrypt_ch11_serpent  170       T14 := T10 xor T09; 
eucrypt_ch11_serpent  171       T15 := X0  and T05; 
eucrypt_ch11_serpent  172       T16 := T11 or T12; 
eucrypt_ch11_serpent  173       Y   := T13 xor T08; 
eucrypt_ch11_serpent  174       X   := T15 xor T16; 
eucrypt_ch11_serpent  175       W   :=     not T14;
eucrypt_ch11_serpent  176     elsif R = 5 then
eucrypt_ch11_serpent  177       -- S5:  15  5  2 11  4 10  9 12  0  3 14  8 13  6  7  1
eucrypt_ch11_serpent  178       -- depth = 4,6,8,6, Total gates=17
eucrypt_ch11_serpent  179       T01 := X1  xor X3; 
eucrypt_ch11_serpent  180       T02 := X1  or X3; 
eucrypt_ch11_serpent  181       T03 := X0  and T01; 
eucrypt_ch11_serpent  182       T04 := X2  xor T02; 
eucrypt_ch11_serpent  183       T05 := T03 xor T04; 
eucrypt_ch11_serpent  184       W   :=     not T05; 
eucrypt_ch11_serpent  185       T07 := X0  xor T01; 
eucrypt_ch11_serpent  186       T08 := X3  or w; 
eucrypt_ch11_serpent  187       T09 := X1  or T05; 
eucrypt_ch11_serpent  188       T10 := X3  xor T08; 
eucrypt_ch11_serpent  189       T11 := X1  or T07; 
eucrypt_ch11_serpent  190       T12 := T03 or w; 
eucrypt_ch11_serpent  191       T13 := T07 or T10; 
eucrypt_ch11_serpent  192       T14 := T01 xor T11; 
eucrypt_ch11_serpent  193       Y   := T09 xor T13; 
eucrypt_ch11_serpent  194       X   := T07 xor T08; 
eucrypt_ch11_serpent  195       Z   := T12 xor T14;
eucrypt_ch11_serpent  196     elsif R = 6 then
eucrypt_ch11_serpent  197       -- S6:   7  2 12  5  8  4  6 11 14  9  1 15 13  3 10  0
eucrypt_ch11_serpent  198       -- depth = 8,3,6,3, Total gates=19
eucrypt_ch11_serpent  199       T01 := X0  and X3; 
eucrypt_ch11_serpent  200       T02 := X1  xor X2; 
eucrypt_ch11_serpent  201       T03 := X0  xor X3; 
eucrypt_ch11_serpent  202       T04 := T01 xor T02; 
eucrypt_ch11_serpent  203       T05 := X1  or X2; 
eucrypt_ch11_serpent  204       X   :=     not T04; 
eucrypt_ch11_serpent  205       T07 := T03 and T05; 
eucrypt_ch11_serpent  206       T08 := X1  and x; 
eucrypt_ch11_serpent  207       T09 := X0  or X2; 
eucrypt_ch11_serpent  208       T10 := T07 xor T08; 
eucrypt_ch11_serpent  209       T11 := X1  or X3; 
eucrypt_ch11_serpent  210       T12 := X2  xor T11; 
eucrypt_ch11_serpent  211       T13 := T09 xor T10; 
eucrypt_ch11_serpent  212       Y   :=     not T13; 
eucrypt_ch11_serpent  213       T15 := X   and T03; 
eucrypt_ch11_serpent  214       Z   := T12 xor T07; 
eucrypt_ch11_serpent  215       T17 := X0  xor X1; 
eucrypt_ch11_serpent  216       T18 := Y   xor T15; 
eucrypt_ch11_serpent  217       W   := T17 xor T18;
eucrypt_ch11_serpent  218     elsif R = 7 then
eucrypt_ch11_serpent  219       -- S7:   1 13 15  0 14  8  2 11  7  4 12 10  9  3  5  6
eucrypt_ch11_serpent  220       -- depth = 10,7,10,4, Total gates=19
eucrypt_ch11_serpent  221       T01 := X0  and X2; 
eucrypt_ch11_serpent  222       T02 :=     not X3; 
eucrypt_ch11_serpent  223       T03 := X0  and T02; 
eucrypt_ch11_serpent  224       T04 := X1  or T01; 
eucrypt_ch11_serpent  225       T05 := X0  and X1; 
eucrypt_ch11_serpent  226       T06 := X2  xor T04; 
eucrypt_ch11_serpent  227       Z   := T03 xor T06; 
eucrypt_ch11_serpent  228       T08 := X2  or z; 
eucrypt_ch11_serpent  229       T09 := X3  or T05; 
eucrypt_ch11_serpent  230       T10 := X0  xor T08; 
eucrypt_ch11_serpent  231       T11 := T04 and z; 
eucrypt_ch11_serpent  232       X   := T09 xor T10; 
eucrypt_ch11_serpent  233       T13 := X1  xor x; 
eucrypt_ch11_serpent  234       T14 := T01 xor x; 
eucrypt_ch11_serpent  235       T15 := X2  xor T05; 
eucrypt_ch11_serpent  236       T16 := T11 or T13; 
eucrypt_ch11_serpent  237       T17 := T02 or T14; 
eucrypt_ch11_serpent  238       W   := T15 xor T17; 
eucrypt_ch11_serpent  239       Y   := X0  xor T16;
eucrypt_ch11_serpent  240     end if;
eucrypt_ch11_serpent  241     X0 := W;
eucrypt_ch11_serpent  242     X1 := X;
eucrypt_ch11_serpent  243     X2 := Y;
eucrypt_ch11_serpent  244     X3 := Z;
eucrypt_ch11_serpent  245   end S;
eucrypt_ch11_serpent  246    
eucrypt_ch11_serpent  247    
eucrypt_ch11_serpent  248   -- Inverse Sbox function
eucrypt_ch11_serpent  249 
eucrypt_ch11_serpent  250   procedure SI (R : Integer; X0, X1, X2, X3 : in out Unsigned_32) is
eucrypt_ch11_serpent  251       T01, T02, T03, T04, T05, T06, T07, T08, T09,
eucrypt_ch11_serpent  252       T10, T11, T12, T13, T14, T15, T16, T17, T18 : Unsigned_32;
eucrypt_ch11_serpent  253       W, X, Y, Z : Unsigned_32;
eucrypt_ch11_serpent  254   begin
eucrypt_ch11_serpent  255     if R = 0 then
eucrypt_ch11_serpent  256       -- InvS0:  13  3 11  0 10  6  5 12  1 14  4  7 15  9  8  2
eucrypt_ch11_serpent  257       -- depth = 8,4,3,6, Total gates=19
eucrypt_ch11_serpent  258       T01 := X2  xor X3; 
eucrypt_ch11_serpent  259       T02 := X0  or X1; 
eucrypt_ch11_serpent  260       T03 := X1  or X2; 
eucrypt_ch11_serpent  261       T04 := X2  and T01; 
eucrypt_ch11_serpent  262       T05 := T02 xor T01; 
eucrypt_ch11_serpent  263       T06 := X0  or T04; 
eucrypt_ch11_serpent  264       Y   :=     not T05; 
eucrypt_ch11_serpent  265       T08 := X1  xor X3; 
eucrypt_ch11_serpent  266       T09 := T03 and T08; 
eucrypt_ch11_serpent  267       T10 := X3  or y; 
eucrypt_ch11_serpent  268       X   := T09 xor T06; 
eucrypt_ch11_serpent  269       T12 := X0  or T05; 
eucrypt_ch11_serpent  270       T13 := X   xor T12; 
eucrypt_ch11_serpent  271       T14 := T03 xor T10; 
eucrypt_ch11_serpent  272       T15 := X0  xor X2; 
eucrypt_ch11_serpent  273       Z   := T14 xor T13; 
eucrypt_ch11_serpent  274       T17 := T05 and T13; 
eucrypt_ch11_serpent  275       T18 := T14 or T17; 
eucrypt_ch11_serpent  276       W   := T15 xor T18;
eucrypt_ch11_serpent  277     elsif R = 1 then
eucrypt_ch11_serpent  278       -- InvS1:   5  8  2 14 15  6 12  3 11  4  7  9  1 13 10  0
eucrypt_ch11_serpent  279       -- depth = 7,4,5,3, Total gates=18
eucrypt_ch11_serpent  280       T01 := X0  xor X1; 
eucrypt_ch11_serpent  281       T02 := X1  or X3; 
eucrypt_ch11_serpent  282       T03 := X0  and X2; 
eucrypt_ch11_serpent  283       T04 := X2  xor T02; 
eucrypt_ch11_serpent  284       T05 := X0  or T04; 
eucrypt_ch11_serpent  285       T06 := T01 and T05; 
eucrypt_ch11_serpent  286       T07 := X3  or T03; 
eucrypt_ch11_serpent  287       T08 := X1  xor T06; 
eucrypt_ch11_serpent  288       T09 := T07 xor T06; 
eucrypt_ch11_serpent  289       T10 := T04 or T03; 
eucrypt_ch11_serpent  290       T11 := X3  and T08; 
eucrypt_ch11_serpent  291       Y   :=     not T09; 
eucrypt_ch11_serpent  292       X   := T10 xor T11; 
eucrypt_ch11_serpent  293       T14 := X0  or y; 
eucrypt_ch11_serpent  294       T15 := T06 xor x; 
eucrypt_ch11_serpent  295       Z   := T01 xor T04; 
eucrypt_ch11_serpent  296       T17 := X2  xor T15; 
eucrypt_ch11_serpent  297       W   := T14 xor T17;
eucrypt_ch11_serpent  298     elsif R = 2 then
eucrypt_ch11_serpent  299       -- InvS2:  12  9 15  4 11 14  1  2  0  3  6 13  5  8 10  7
eucrypt_ch11_serpent  300       -- depth = 3,6,8,3, Total gates=18
eucrypt_ch11_serpent  301       T01 := X0  xor X3; 
eucrypt_ch11_serpent  302       T02 := X2  xor X3; 
eucrypt_ch11_serpent  303       T03 := X0  and X2; 
eucrypt_ch11_serpent  304       T04 := X1  or T02; 
eucrypt_ch11_serpent  305       W   := T01 xor T04; 
eucrypt_ch11_serpent  306       T06 := X0  or X2; 
eucrypt_ch11_serpent  307       T07 := X3  or w; 
eucrypt_ch11_serpent  308       T08 :=     not X3; 
eucrypt_ch11_serpent  309       T09 := X1  and T06; 
eucrypt_ch11_serpent  310       T10 := T08 or T03; 
eucrypt_ch11_serpent  311       T11 := X1  and T07; 
eucrypt_ch11_serpent  312       T12 := T06 and T02; 
eucrypt_ch11_serpent  313       Z   := T09 xor T10; 
eucrypt_ch11_serpent  314       X   := T12 xor T11; 
eucrypt_ch11_serpent  315       T15 := X2  and z; 
eucrypt_ch11_serpent  316       T16 := W   xor x; 
eucrypt_ch11_serpent  317       T17 := T10 xor T15; 
eucrypt_ch11_serpent  318       Y   := T16 xor T17;
eucrypt_ch11_serpent  319     elsif R = 3 then
eucrypt_ch11_serpent  320       -- InvS3:   0  9 10  7 11 14  6 13  3  5 12  2  4  8 15  1
eucrypt_ch11_serpent  321       -- depth = 3,6,4,4, Total gates=17
eucrypt_ch11_serpent  322       T01 := X2  or X3; 
eucrypt_ch11_serpent  323       T02 := X0  or X3; 
eucrypt_ch11_serpent  324       T03 := X2  xor T02; 
eucrypt_ch11_serpent  325       T04 := X1  xor T02; 
eucrypt_ch11_serpent  326       T05 := X0  xor X3; 
eucrypt_ch11_serpent  327       T06 := T04 and T03; 
eucrypt_ch11_serpent  328       T07 := X1  and T01; 
eucrypt_ch11_serpent  329       Y   := T05 xor T06; 
eucrypt_ch11_serpent  330       T09 := X0  xor T03; 
eucrypt_ch11_serpent  331       W   := T07 xor T03; 
eucrypt_ch11_serpent  332       T11 := W   or T05; 
eucrypt_ch11_serpent  333       T12 := T09 and T11; 
eucrypt_ch11_serpent  334       T13 := X0  and y; 
eucrypt_ch11_serpent  335       T14 := T01 xor T05; 
eucrypt_ch11_serpent  336       X   := X1  xor T12; 
eucrypt_ch11_serpent  337       T16 := X1  or T13; 
eucrypt_ch11_serpent  338       Z   := T14 xor T16;
eucrypt_ch11_serpent  339     elsif R = 4 then
eucrypt_ch11_serpent  340       -- InvS4:   5  0  8  3 10  9  7 14  2 12 11  6  4 15 13  1
eucrypt_ch11_serpent  341       -- depth = 6,4,7,3, Total gates=17
eucrypt_ch11_serpent  342       T01 := X1  or X3; 
eucrypt_ch11_serpent  343       T02 := X2  or X3; 
eucrypt_ch11_serpent  344       T03 := X0  and T01; 
eucrypt_ch11_serpent  345       T04 := X1  xor T02; 
eucrypt_ch11_serpent  346       T05 := X2  xor X3; 
eucrypt_ch11_serpent  347       T06 :=     not T03; 
eucrypt_ch11_serpent  348       T07 := X0  and T04; 
eucrypt_ch11_serpent  349       X   := T05 xor T07; 
eucrypt_ch11_serpent  350       T09 := X   or T06; 
eucrypt_ch11_serpent  351       T10 := X0  xor T07; 
eucrypt_ch11_serpent  352       T11 := T01 xor T09; 
eucrypt_ch11_serpent  353       T12 := X3  xor T04; 
eucrypt_ch11_serpent  354       T13 := X2  or T10; 
eucrypt_ch11_serpent  355       Z   := T03 xor T12; 
eucrypt_ch11_serpent  356       T15 := X0  xor T04; 
eucrypt_ch11_serpent  357       Y   := T11 xor T13; 
eucrypt_ch11_serpent  358       W   := T15 xor T09;
eucrypt_ch11_serpent  359     elsif R = 5 then
eucrypt_ch11_serpent  360       -- InvS5:   8 15  2  9  4  1 13 14 11  6  5  3  7 12 10  0
eucrypt_ch11_serpent  361       -- depth = 4,6,9,7, Total gates=17
eucrypt_ch11_serpent  362       T01 := X0  and X3; 
eucrypt_ch11_serpent  363       T02 := X2  xor T01; 
eucrypt_ch11_serpent  364       T03 := X0  xor X3; 
eucrypt_ch11_serpent  365       T04 := X1  and T02; 
eucrypt_ch11_serpent  366       T05 := X0  and X2; 
eucrypt_ch11_serpent  367       W   := T03 xor T04; 
eucrypt_ch11_serpent  368       T07 := X0  and w; 
eucrypt_ch11_serpent  369       T08 := T01 xor w; 
eucrypt_ch11_serpent  370       T09 := X1  or T05; 
eucrypt_ch11_serpent  371       T10 :=     not X1; 
eucrypt_ch11_serpent  372       X   := T08 xor T09; 
eucrypt_ch11_serpent  373       T12 := T10 or T07; 
eucrypt_ch11_serpent  374       T13 := W   or x; 
eucrypt_ch11_serpent  375       Z   := T02 xor T12; 
eucrypt_ch11_serpent  376       T15 := T02 xor T13; 
eucrypt_ch11_serpent  377       T16 := X1  xor X3; 
eucrypt_ch11_serpent  378       Y   := T16 xor T15;
eucrypt_ch11_serpent  379     elsif R = 6 then
eucrypt_ch11_serpent  380       -- InvS6:  15 10  1 13  5  3  6  0  4  9 14  7  2 12  8 11
eucrypt_ch11_serpent  381       -- depth = 5,3,8,6, Total gates=19
eucrypt_ch11_serpent  382       T01 := X0  xor X2; 
eucrypt_ch11_serpent  383       T02 :=     not X2; 
eucrypt_ch11_serpent  384       T03 := X1  and T01; 
eucrypt_ch11_serpent  385       T04 := X1  or T02; 
eucrypt_ch11_serpent  386       T05 := X3  or T03; 
eucrypt_ch11_serpent  387       T06 := X1  xor X3; 
eucrypt_ch11_serpent  388       T07 := X0  and T04; 
eucrypt_ch11_serpent  389       T08 := X0  or T02; 
eucrypt_ch11_serpent  390       T09 := T07 xor T05; 
eucrypt_ch11_serpent  391       X   := T06 xor T08; 
eucrypt_ch11_serpent  392       W   :=     not T09; 
eucrypt_ch11_serpent  393       T12 := X1  and w; 
eucrypt_ch11_serpent  394       T13 := T01 and T05; 
eucrypt_ch11_serpent  395       T14 := T01 xor T12; 
eucrypt_ch11_serpent  396       T15 := T07 xor T13; 
eucrypt_ch11_serpent  397       T16 := X3  or T02; 
eucrypt_ch11_serpent  398       T17 := X0  xor x; 
eucrypt_ch11_serpent  399       Z   := T17 xor T15; 
eucrypt_ch11_serpent  400       Y   := T16 xor T14;
eucrypt_ch11_serpent  401     elsif R = 7 then
eucrypt_ch11_serpent  402       -- InvS7:   3  0  6 13  9 14 15  8  5 12 11  7 10  1  4  2
eucrypt_ch11_serpent  403       -- depth := 9,7,3,3, Total gates:=18
eucrypt_ch11_serpent  404       T01 := X0  and X1;
eucrypt_ch11_serpent  405       T02 := X0  or X1; 
eucrypt_ch11_serpent  406       T03 := X2  or T01; 
eucrypt_ch11_serpent  407       T04 := X3  and T02; 
eucrypt_ch11_serpent  408       Z   := T03 xor T04; 
eucrypt_ch11_serpent  409       T06 := X1  xor T04; 
eucrypt_ch11_serpent  410       T07 := X3  xor z; 
eucrypt_ch11_serpent  411       T08 :=     not T07; 
eucrypt_ch11_serpent  412       T09 := T06 or T08; 
eucrypt_ch11_serpent  413       T10 := X1  xor X3; 
eucrypt_ch11_serpent  414       T11 := X0  or X3; 
eucrypt_ch11_serpent  415       X   := X0  xor T09; 
eucrypt_ch11_serpent  416       T13 := X2  xor T06; 
eucrypt_ch11_serpent  417       T14 := X2  and T11; 
eucrypt_ch11_serpent  418       T15 := X3  or x; 
eucrypt_ch11_serpent  419       T16 := T01 or T10; 
eucrypt_ch11_serpent  420       W   := T13 xor T15; 
eucrypt_ch11_serpent  421       Y   := T14 xor T16;
eucrypt_ch11_serpent  422     end if;
eucrypt_ch11_serpent  423     X0 := W;
eucrypt_ch11_serpent  424     X1 := X;
eucrypt_ch11_serpent  425     X2 := Y;
eucrypt_ch11_serpent  426     X3 := Z;
eucrypt_ch11_serpent  427   end SI;
eucrypt_ch11_serpent  428 
eucrypt_ch11_serpent  429 
eucrypt_ch11_serpent  430   -- Linear Transform
eucrypt_ch11_serpent  431    
eucrypt_ch11_serpent  432   procedure Tr (X0, X1, X2, X3 : in out Unsigned_32) is
eucrypt_ch11_serpent  433   begin
eucrypt_ch11_serpent  434     X0 := Rotate_Left(X0, 13);
eucrypt_ch11_serpent  435     X2 := Rotate_Left(X2, 3);
eucrypt_ch11_serpent  436     X1 := X1 xor X0 xor X2;
eucrypt_ch11_serpent  437     X3 := X3 xor X2 xor Shift_Left(X0, 3);
eucrypt_ch11_serpent  438     X1 := Rotate_Left(X1, 1);
eucrypt_ch11_serpent  439     X3 := Rotate_Left(X3, 7);
eucrypt_ch11_serpent  440     X0 := X0 xor X1 xor X3;
eucrypt_ch11_serpent  441     X2 := X2 xor X3 xor Shift_Left(X1, 7);
eucrypt_ch11_serpent  442     X0 := Rotate_Left(X0, 5);
eucrypt_ch11_serpent  443     X2 := Rotate_Left(X2, 22);
eucrypt_ch11_serpent  444   end Tr;
eucrypt_ch11_serpent  445    
eucrypt_ch11_serpent  446 
eucrypt_ch11_serpent  447   -- Inverse Linear Transform
eucrypt_ch11_serpent  448    
eucrypt_ch11_serpent  449   procedure TrI (X0, X1, X2, X3 : in out Unsigned_32) is
eucrypt_ch11_serpent  450   begin
eucrypt_ch11_serpent  451     X2 := Rotate_Right(X2, 22);
eucrypt_ch11_serpent  452     X0 := Rotate_Right(X0, 5);
eucrypt_ch11_serpent  453     X2 := X2 xor X3 xor Shift_Left(X1, 7);
eucrypt_ch11_serpent  454     X0 := X0 xor X1 xor X3;
eucrypt_ch11_serpent  455     X3 := Rotate_Right(X3, 7);
eucrypt_ch11_serpent  456     X1 := Rotate_Right(X1, 1);
eucrypt_ch11_serpent  457     X3 := X3 xor X2 xor Shift_Left(X0, 3);
eucrypt_ch11_serpent  458     X1 := X1 xor X0 xor X2;
eucrypt_ch11_serpent  459     X2 := Rotate_Right(X2, 3);
eucrypt_ch11_serpent  460     X0 := Rotate_Right(X0, 13);
eucrypt_ch11_serpent  461   end TrI;
eucrypt_ch11_serpent  462    
eucrypt_ch11_serpent  463  
eucrypt_ch11_serpent  464   procedure Keying (W : Key_Schedule;
eucrypt_ch11_serpent  465                     R : Integer;
eucrypt_ch11_serpent  466        X0, X1, X2, X3 : in out Unsigned_32) is
eucrypt_ch11_serpent  467   begin
eucrypt_ch11_serpent  468     X0 := X0 xor W(4*R);
eucrypt_ch11_serpent  469     X1 := X1 xor W(4*R+1);
eucrypt_ch11_serpent  470     X2 := X2 xor W(4*R+2);
eucrypt_ch11_serpent  471     X3 := X3 xor W(4*R+3);
eucrypt_ch11_serpent  472   end Keying;
eucrypt_ch11_serpent  473    
eucrypt_ch11_serpent  474    
eucrypt_ch11_serpent  475   pragma Inline(S, SI, Tr, TrI, Keying);
eucrypt_ch11_serpent  476 
eucrypt_ch11_serpent  477 
eucrypt_ch11_serpent  478   procedure Prepare_Key (K : in Key; W : out Key_Schedule) is
eucrypt_ch11_serpent  479   begin
eucrypt_ch11_serpent  480     for I in 0..7 loop
eucrypt_ch11_serpent  481       W(-8+I) := Bytes_To_Word(K(4*I .. 4*I+3));
eucrypt_ch11_serpent  482     end loop;
eucrypt_ch11_serpent  483     for I in 0..131 loop
eucrypt_ch11_serpent  484       W(I) := Rotate_Left(W(I-8) xor W(I-5) xor W(I-3) xor W(I-1) xor
eucrypt_ch11_serpent  485               16#9e3779b9# xor Unsigned_32(I), 11);
eucrypt_ch11_serpent  486     end loop;
eucrypt_ch11_serpent  487     S(3, W(  0), W(  1), W(  2), W(  3));
eucrypt_ch11_serpent  488     S(2, W(  4), W(  5), W(  6), W(  7));
eucrypt_ch11_serpent  489     S(1, W(  8), W(  9), W( 10), W( 11));
eucrypt_ch11_serpent  490     S(0, W( 12), W( 13), W( 14), W( 15));
eucrypt_ch11_serpent  491     S(7, W( 16), W( 17), W( 18), W( 19));
eucrypt_ch11_serpent  492     S(6, W( 20), W( 21), W( 22), W( 23));
eucrypt_ch11_serpent  493     S(5, W( 24), W( 25), W( 26), W( 27));
eucrypt_ch11_serpent  494     S(4, W( 28), W( 29), W( 30), W( 31));
eucrypt_ch11_serpent  495     S(3, W( 32), W( 33), W( 34), W( 35));
eucrypt_ch11_serpent  496     S(2, W( 36), W( 37), W( 38), W( 39));
eucrypt_ch11_serpent  497     S(1, W( 40), W( 41), W( 42), W( 43));
eucrypt_ch11_serpent  498     S(0, W( 44), W( 45), W( 46), W( 47));
eucrypt_ch11_serpent  499     S(7, W( 48), W( 49), W( 50), W( 51));
eucrypt_ch11_serpent  500     S(6, W( 52), W( 53), W( 54), W( 55));
eucrypt_ch11_serpent  501     S(5, W( 56), W( 57), W( 58), W( 59));
eucrypt_ch11_serpent  502     S(4, W( 60), W( 61), W( 62), W( 63));
eucrypt_ch11_serpent  503     S(3, W( 64), W( 65), W( 66), W( 67));
eucrypt_ch11_serpent  504     S(2, W( 68), W( 69), W( 70), W( 71));
eucrypt_ch11_serpent  505     S(1, W( 72), W( 73), W( 74), W( 75));
eucrypt_ch11_serpent  506     S(0, W( 76), W( 77), W( 78), W( 79));
eucrypt_ch11_serpent  507     S(7, W( 80), W( 81), W( 82), W( 83));
eucrypt_ch11_serpent  508     S(6, W( 84), W( 85), W( 86), W( 87));
eucrypt_ch11_serpent  509     S(5, W( 88), W( 89), W( 90), W( 91));
eucrypt_ch11_serpent  510     S(4, W( 92), W( 93), W( 94), W( 95));
eucrypt_ch11_serpent  511     S(3, W( 96), W( 97), W( 98), W( 99));
eucrypt_ch11_serpent  512     S(2, W(100), W(101), W(102), W(103));
eucrypt_ch11_serpent  513     S(1, W(104), W(105), W(106), W(107));
eucrypt_ch11_serpent  514     S(0, W(108), W(109), W(110), W(111));
eucrypt_ch11_serpent  515     S(7, W(112), W(113), W(114), W(115));
eucrypt_ch11_serpent  516     S(6, W(116), W(117), W(118), W(119));
eucrypt_ch11_serpent  517     S(5, W(120), W(121), W(122), W(123));
eucrypt_ch11_serpent  518     S(4, W(124), W(125), W(126), W(127));
eucrypt_ch11_serpent  519     S(3, W(128), W(129), W(130), W(131));
eucrypt_ch11_serpent  520   end Prepare_Key;
eucrypt_ch11_serpent  521    
eucrypt_ch11_serpent  522    
eucrypt_ch11_serpent  523   procedure Encrypt (W : in Key_Schedule; Plaintext  :  in Block;
eucrypt_ch11_serpent  524             Ciphertext : out Block) is
eucrypt_ch11_serpent  525     X0, X1, X2, X3 : Unsigned_32;
eucrypt_ch11_serpent  526   begin
eucrypt_ch11_serpent  527     X0 := Bytes_To_Word(Plaintext( 0 ..  3));
eucrypt_ch11_serpent  528     X1 := Bytes_To_Word(Plaintext( 4 ..  7));
eucrypt_ch11_serpent  529     X2 := Bytes_To_Word(Plaintext( 8 .. 11));
eucrypt_ch11_serpent  530     X3 := Bytes_To_Word(Plaintext(12 .. 15));
eucrypt_ch11_serpent  531 
eucrypt_ch11_serpent  532     Keying(W,  0, X0, X1, X2, X3); S(0, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  533     Keying(W,  1, X0, X1, X2, X3); S(1, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  534     Keying(W,  2, X0, X1, X2, X3); S(2, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  535     Keying(W,  3, X0, X1, X2, X3); S(3, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  536     Keying(W,  4, X0, X1, X2, X3); S(4, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  537     Keying(W,  5, X0, X1, X2, X3); S(5, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  538     Keying(W,  6, X0, X1, X2, X3); S(6, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  539     Keying(W,  7, X0, X1, X2, X3); S(7, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  540     Keying(W,  8, X0, X1, X2, X3); S(0, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  541     Keying(W,  9, X0, X1, X2, X3); S(1, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  542     Keying(W, 10, X0, X1, X2, X3); S(2, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  543     Keying(W, 11, X0, X1, X2, X3); S(3, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  544     Keying(W, 12, X0, X1, X2, X3); S(4, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  545     Keying(W, 13, X0, X1, X2, X3); S(5, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  546     Keying(W, 14, X0, X1, X2, X3); S(6, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  547     Keying(W, 15, X0, X1, X2, X3); S(7, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  548     Keying(W, 16, X0, X1, X2, X3); S(0, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  549     Keying(W, 17, X0, X1, X2, X3); S(1, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  550     Keying(W, 18, X0, X1, X2, X3); S(2, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  551     Keying(W, 19, X0, X1, X2, X3); S(3, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  552     Keying(W, 20, X0, X1, X2, X3); S(4, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  553     Keying(W, 21, X0, X1, X2, X3); S(5, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  554     Keying(W, 22, X0, X1, X2, X3); S(6, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  555     Keying(W, 23, X0, X1, X2, X3); S(7, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  556     Keying(W, 24, X0, X1, X2, X3); S(0, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  557     Keying(W, 25, X0, X1, X2, X3); S(1, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  558     Keying(W, 26, X0, X1, X2, X3); S(2, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  559     Keying(W, 27, X0, X1, X2, X3); S(3, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  560     Keying(W, 28, X0, X1, X2, X3); S(4, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  561     Keying(W, 29, X0, X1, X2, X3); S(5, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  562     Keying(W, 30, X0, X1, X2, X3); S(6, X0, X1, X2, X3); Tr(X0, X1, X2, X3);
eucrypt_ch11_serpent  563     Keying(W, 31, X0, X1, X2, X3);
eucrypt_ch11_serpent  564     S(7, X0, X1, X2, X3);
eucrypt_ch11_serpent  565     Keying(W, 32, X0, X1, X2, X3);
eucrypt_ch11_serpent  566       
eucrypt_ch11_serpent  567     Ciphertext( 0 ..  3) := Word_To_Bytes(X0);
eucrypt_ch11_serpent  568     Ciphertext( 4 ..  7) := Word_To_Bytes(X1);
eucrypt_ch11_serpent  569     Ciphertext( 8 .. 11) := Word_To_Bytes(X2);
eucrypt_ch11_serpent  570     Ciphertext(12 .. 15) := Word_To_Bytes(X3);
eucrypt_ch11_serpent  571   end Encrypt;
eucrypt_ch11_serpent  572 
eucrypt_ch11_serpent  573 
eucrypt_ch11_serpent  574   procedure Decrypt (W : in Key_Schedule; Ciphertext :  in Block;
eucrypt_ch11_serpent  575             Plaintext  : out Block) is
eucrypt_ch11_serpent  576     X0, X1, X2, X3 : Unsigned_32;
eucrypt_ch11_serpent  577   begin
eucrypt_ch11_serpent  578     X0 := Bytes_To_Word(Ciphertext( 0 ..  3));
eucrypt_ch11_serpent  579     X1 := Bytes_To_Word(Ciphertext( 4 ..  7));
eucrypt_ch11_serpent  580     X2 := Bytes_To_Word(Ciphertext( 8 .. 11));
eucrypt_ch11_serpent  581     X3 := Bytes_To_Word(Ciphertext(12 .. 15));
eucrypt_ch11_serpent  582 
eucrypt_ch11_serpent  583     Keying(W, 32, X0, X1, X2, X3);
eucrypt_ch11_serpent  584     SI(7, X0, X1, X2, X3);
eucrypt_ch11_serpent  585     Keying(W, 31, X0, X1, X2, X3);
eucrypt_ch11_serpent  586     TrI(X0, X1, X2, X3); SI(6, X0, X1, X2, X3); Keying(W,30, X0, X1, X2, X3);
eucrypt_ch11_serpent  587     TrI(X0, X1, X2, X3); SI(5, X0, X1, X2, X3); Keying(W,29, X0, X1, X2, X3);
eucrypt_ch11_serpent  588     TrI(X0, X1, X2, X3); SI(4, X0, X1, X2, X3); Keying(W,28, X0, X1, X2, X3);
eucrypt_ch11_serpent  589     TrI(X0, X1, X2, X3); SI(3, X0, X1, X2, X3); Keying(W,27, X0, X1, X2, X3);
eucrypt_ch11_serpent  590     TrI(X0, X1, X2, X3); SI(2, X0, X1, X2, X3); Keying(W,26, X0, X1, X2, X3);
eucrypt_ch11_serpent  591     TrI(X0, X1, X2, X3); SI(1, X0, X1, X2, X3); Keying(W,25, X0, X1, X2, X3);
eucrypt_ch11_serpent  592     TrI(X0, X1, X2, X3); SI(0, X0, X1, X2, X3); Keying(W,24, X0, X1, X2, X3);
eucrypt_ch11_serpent  593     TrI(X0, X1, X2, X3); SI(7, X0, X1, X2, X3); Keying(W,23, X0, X1, X2, X3);
eucrypt_ch11_serpent  594     TrI(X0, X1, X2, X3); SI(6, X0, X1, X2, X3); Keying(W,22, X0, X1, X2, X3);
eucrypt_ch11_serpent  595     TrI(X0, X1, X2, X3); SI(5, X0, X1, X2, X3); Keying(W,21, X0, X1, X2, X3);
eucrypt_ch11_serpent  596     TrI(X0, X1, X2, X3); SI(4, X0, X1, X2, X3); Keying(W,20, X0, X1, X2, X3);
eucrypt_ch11_serpent  597     TrI(X0, X1, X2, X3); SI(3, X0, X1, X2, X3); Keying(W,19, X0, X1, X2, X3);
eucrypt_ch11_serpent  598     TrI(X0, X1, X2, X3); SI(2, X0, X1, X2, X3); Keying(W,18, X0, X1, X2, X3);
eucrypt_ch11_serpent  599     TrI(X0, X1, X2, X3); SI(1, X0, X1, X2, X3); Keying(W,17, X0, X1, X2, X3);
eucrypt_ch11_serpent  600     TrI(X0, X1, X2, X3); SI(0, X0, X1, X2, X3); Keying(W,16, X0, X1, X2, X3);
eucrypt_ch11_serpent  601     TrI(X0, X1, X2, X3); SI(7, X0, X1, X2, X3); Keying(W,15, X0, X1, X2, X3);
eucrypt_ch11_serpent  602     TrI(X0, X1, X2, X3); SI(6, X0, X1, X2, X3); Keying(W,14, X0, X1, X2, X3);
eucrypt_ch11_serpent  603     TrI(X0, X1, X2, X3); SI(5, X0, X1, X2, X3); Keying(W,13, X0, X1, X2, X3);
eucrypt_ch11_serpent  604     TrI(X0, X1, X2, X3); SI(4, X0, X1, X2, X3); Keying(W,12, X0, X1, X2, X3);
eucrypt_ch11_serpent  605     TrI(X0, X1, X2, X3); SI(3, X0, X1, X2, X3); Keying(W,11, X0, X1, X2, X3);
eucrypt_ch11_serpent  606     TrI(X0, X1, X2, X3); SI(2, X0, X1, X2, X3); Keying(W,10, X0, X1, X2, X3);
eucrypt_ch11_serpent  607     TrI(X0, X1, X2, X3); SI(1, X0, X1, X2, X3); Keying(W, 9, X0, X1, X2, X3);
eucrypt_ch11_serpent  608     TrI(X0, X1, X2, X3); SI(0, X0, X1, X2, X3); Keying(W, 8, X0, X1, X2, X3);
eucrypt_ch11_serpent  609     TrI(X0, X1, X2, X3); SI(7, X0, X1, X2, X3); Keying(W, 7, X0, X1, X2, X3);
eucrypt_ch11_serpent  610     TrI(X0, X1, X2, X3); SI(6, X0, X1, X2, X3); Keying(W, 6, X0, X1, X2, X3);
eucrypt_ch11_serpent  611     TrI(X0, X1, X2, X3); SI(5, X0, X1, X2, X3); Keying(W, 5, X0, X1, X2, X3);
eucrypt_ch11_serpent  612     TrI(X0, X1, X2, X3); SI(4, X0, X1, X2, X3); Keying(W, 4, X0, X1, X2, X3);
eucrypt_ch11_serpent  613     TrI(X0, X1, X2, X3); SI(3, X0, X1, X2, X3); Keying(W, 3, X0, X1, X2, X3);
eucrypt_ch11_serpent  614     TrI(X0, X1, X2, X3); SI(2, X0, X1, X2, X3); Keying(W, 2, X0, X1, X2, X3);
eucrypt_ch11_serpent  615     TrI(X0, X1, X2, X3); SI(1, X0, X1, X2, X3); Keying(W, 1, X0, X1, X2, X3);
eucrypt_ch11_serpent  616     TrI(X0, X1, X2, X3); SI(0, X0, X1, X2, X3); Keying(W, 0, X0, X1, X2, X3);
eucrypt_ch11_serpent  617       
eucrypt_ch11_serpent  618     Plaintext( 0 ..  3) := Word_To_Bytes(X0);
eucrypt_ch11_serpent  619     Plaintext( 4 ..  7) := Word_To_Bytes(X1);
eucrypt_ch11_serpent  620     Plaintext( 8 .. 11) := Word_To_Bytes(X2);
eucrypt_ch11_serpent  621     Plaintext(12 .. 15) := Word_To_Bytes(X3);
eucrypt_ch11_serpent  622   end Decrypt;
eucrypt_ch11_serpent  623 
eucrypt_ch11_serpent  624 
eucrypt_ch11_serpent  625   procedure Selftest is
eucrypt_ch11_serpent  626     K     : Key    := (others => 0);
eucrypt_ch11_serpent  627     P     : Block  := (others => 0);
eucrypt_ch11_serpent  628     P2, C : Block;
eucrypt_ch11_serpent  629     W     : Key_Schedule;
eucrypt_ch11_serpent  630   begin
eucrypt_ch11_serpent  631     for I in 1 .. 128 loop
eucrypt_ch11_serpent  632       Prepare_Key(K, W);
eucrypt_ch11_serpent  633       Encrypt(W, P, C);
eucrypt_ch11_serpent  634       Decrypt(W, C, P2);
eucrypt_ch11_serpent  635       if (P2 /= P) then
eucrypt_ch11_serpent  636         raise Implementation_Error;
eucrypt_ch11_serpent  637       end if;
eucrypt_ch11_serpent  638       P           := K( 0 .. 15);
eucrypt_ch11_serpent  639       K( 0 .. 15) := K(16 .. 31);
eucrypt_ch11_serpent  640       K(16 .. 31) := C;
eucrypt_ch11_serpent  641     end loop;
eucrypt_ch11_serpent  642     if C /= (16#A2#, 16#46#, 16#AB#, 16#69#, 16#0A#, 16#E6#, 16#8D#, 16#FB#,
eucrypt_ch11_serpent  643              16#02#, 16#04#, 16#CB#, 16#E2#, 16#8E#, 16#D8#, 16#EB#, 16#7A#)
eucrypt_ch11_serpent  644       then
eucrypt_ch11_serpent  645       raise Implementation_Error;
eucrypt_ch11_serpent  646     end if;
eucrypt_ch11_serpent  647   end Selftest;
eucrypt_ch11_serpent  648 
eucrypt_ch11_serpent  649 end SMG_Serpent;