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{******************************************************************************}
{* DCPcrypt v2.0 written by David Barton (crypto@cityinthesky.co.uk) **********}
{******************************************************************************}
{* A binary compatible (with Total Commander) implementation of CRC32 *}
{******************************************************************************}
{* Copyright (C) 2011-2015 Alexander Koblov (alexx2000@mail.ru) *}
{* Permission is hereby granted, free of charge, to any person obtaining a *}
{* copy of this software and associated documentation files (the "Software"), *}
{* to deal in the Software without restriction, including without limitation *}
{* the rights to use, copy, modify, merge, publish, distribute, sublicense, *}
{* and/or sell copies of the Software, and to permit persons to whom the *}
{* Software is furnished to do so, subject to the following conditions: *}
{* *}
{* The above copyright notice and this permission notice shall be included in *}
{* all copies or substantial portions of the Software. *}
{* *}
{* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *}
{* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *}
{* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *}
{* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER *}
{* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING *}
{* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER *}
{* DEALINGS IN THE SOFTWARE. *}
{******************************************************************************}
unit DCPcrc32;
{$mode objfpc}{$H+}
interface
uses
Classes, Sysutils, DCPcrypt2, DCPconst, DCcrc32;
type
{ TDCP_crc32 }
TDCP_crc32 = class(TDCP_hash)
protected
CurrentHash: LongWord;
public
class function GetId: integer; override;
class function GetAlgorithm: string; override;
class function GetHashSize: integer; override;
class function SelfTest: boolean; override;
constructor Create(AOwner: TComponent); override;
procedure Init; override;
procedure Burn; override;
procedure Update(const Buffer; Size: longword); override;
procedure Final(var Digest); override;
end;
implementation
{$R-}{$Q-}
{ TDCP_crc32 }
class function TDCP_crc32.GetHashSize: integer;
begin
Result:= 32;
end;
class function TDCP_crc32.GetId: integer;
begin
Result:= DCP_crc32;
end;
class function TDCP_crc32.GetAlgorithm: string;
begin
Result:= 'CRC32';
end;
class function TDCP_crc32.SelfTest: boolean;
const
Test1Out: array[0..3] of byte=($35,$24,$41,$C2);
Test2Out: array[0..3] of byte=($4C,$27,$50,$BD);
var
TestHash: TDCP_crc32;
TestOut: array[0..3] of byte;
begin
dcpFillChar(TestOut, SizeOf(TestOut), 0);
TestHash:= TDCP_crc32.Create(nil);
TestHash.Init;
TestHash.UpdateStr('abc');
TestHash.Final(TestOut);
Result:= CompareMem(@TestOut,@Test1Out,Sizeof(Test1Out));
TestHash.Init;
TestHash.UpdateStr('abcdefghijklmnopqrstuvwxyz');
TestHash.Final(TestOut);
Result:= CompareMem(@TestOut,@Test2Out,Sizeof(Test2Out)) and Result;
TestHash.Free;
end;
constructor TDCP_crc32.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
end;
procedure TDCP_crc32.Init;
begin
Burn;
CurrentHash:= 0;
fInitialized:= true;
end;
procedure TDCP_crc32.Burn;
begin
CurrentHash:= 0;
fInitialized:= false;
end;
procedure TDCP_crc32.Update(const Buffer; Size: longword);
var
Bytes: PByte;
begin
Bytes:= @Buffer;
CurrentHash:= crc32_16bytes(Bytes, Size, CurrentHash);
end;
procedure TDCP_crc32.Final(var Digest);
begin
if not fInitialized then
raise EDCP_hash.Create('Hash not initialized');
CurrentHash:= SwapEndian(CurrentHash);
Move(CurrentHash, Digest, Sizeof(CurrentHash));
Burn;
end;
end.
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