(*

 * Hedgewars, a free turn based strategy game

 * Copyright (c) 2004-2007 Andrey Korotaev <unC0Rr@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; version 2 of the License

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA

 *)

unit uSHA;

interface

uses SDLh;

type TSHA1Context = packed record

                    H: array[0..4] of LongWord;

                    Length, CurrLength: Int64;

                    Buf: array[0..63] of byte;

                    end;

     TSHA1Digest =  array[0..4] of LongWord;

procedure SHA1Init(var Context: TSHA1Context);

procedure SHA1Update(var Context: TSHA1Context; Buf: PByteArray; Length: LongWord);

procedure SHA1UpdateLongwords(var Context: TSHA1Context; Buf: PLongwordArray; Length: LongWord);

function  SHA1Final(Context: TSHA1Context): TSHA1Digest;

implementation

function rol(x: LongWord; y: Byte): LongWord;

begin

  rol:= (X shl y) or (X shr (32 - y))

end;

function Ft(t, b, c, d: LongWord): LongWord;

begin

case t of

      0..19: Ft := (b and c) or ((not b) and d);

     20..39: Ft :=  b xor c xor d;

     40..59: Ft := (b and c) or (b and d) or (c and d);

     else    Ft :=  b xor c xor d;

  end;

end;

function Kt(t: Byte): LongWord;

begin

  case t of

     0..19: Kt := $5A827999;

    20..39: Kt := $6ED9EBA1;

    40..59: Kt := $8F1BBCDC;

  else

    Kt := $CA62C1D6

  end;

end;

procedure SHA1Hash(var Context: TSHA1Context);

var S: array[0..4 ] of LongWord;

    W: array[0..79] of LongWord;

    i, t: LongWord;

begin

move(Context.H, S, sizeof(S));

for i:= 0 to 15 do

    SDLNet_Write32(PLongWordArray(@Context.Buf)^[i], @W[i]);

for i := 16 to 79 do

    W[i] := rol(W[i - 3] xor W[i - 8] xor W[i - 14] xor W[i - 16], 1);

for i := 0 to 79 do

    begin

    t:= rol(S[0], 5) + Ft(i, S[1], S[2], S[3]) + S[4] + W[i] + Kt(i);

    S[4]:= S[3];

    S[3]:= S[2];

    S[2]:= rol(S[1], 30);

    S[1]:= S[0];

    S[0]:= t

    end;

for i := 0 to 4 do

    Context.H[i]:= Context.H[i] + S[i]

end;

procedure SHA1Init(var Context: TSHA1Context);

begin

  with Context do

       begin

       Length    := 0;

       CurrLength:= 0;

       H[0]:= $67452301;

       H[1]:= $EFCDAB89;

       H[2]:= $98BADCFE;

       H[3]:= $10325476;

       H[4]:= $C3D2E1F0

  end

end;

procedure SHA1Update(var Context: TSHA1Context; Buf: PByteArray; Length: LongWord);

var i: Longword;

begin

for i:= 0 to Pred(Length) do

    begin

    Context.Buf[Context.CurrLength]:= Buf^[i];

    inc(Context.CurrLength);

    if Context.CurrLength = 64 then

       begin

       SHA1Hash(Context);

       inc(Context.Length, 512);

       Context.CurrLength:= 0

       end

    end

end;

procedure SHA1UpdateLongwords(var Context: TSHA1Context; Buf: PLongwordArray; Length: LongWord);

var i: Longword;

begin

for i:= 0 to Pred(Length div 4) do

    begin

    SDLNet_Write32(Buf^[i], @Context.Buf[Context.CurrLength]);

    inc(Context.CurrLength, 4);

    if Context.CurrLength = 64 then

       begin

       SHA1Hash(Context);

       inc(Context.Length, 512);

       Context.CurrLength:= 0

       end

    end

end;

function  SHA1Final(Context: TSHA1Context): TSHA1Digest;

var i: LongWord;

begin

Context.Length:= Context.Length + Context.CurrLength shl 3;

Context.Buf[Context.CurrLength]:= $80;

inc(Context.CurrLength);

if Context.CurrLength > 56 then

   begin

   FillChar(Context.Buf[Context.CurrLength], 64 - Context.CurrLength, 0);

   Context.CurrLength:= 64;

   SHA1Hash(Context);

   Context.CurrLength:=0

   end;

FillChar(Context.Buf[Context.CurrLength], 56 - Context.CurrLength, 0);

for i:= 56 to 63 do

    Context.Buf[i] := (Context.Length shr ((63 - i) * 8)) and $FF;

SHA1Hash(Context);

for i:= 0 to 4 do SHA1Final[i]:= Context.H[i];

FillChar(Context, sizeof(Context), 0)

end;

end.