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| ///////////////////////////////////////////////////////////////////////////
// //
// Copyright (c) 2015 by Charta Software B.V. //
// All rights reserved //
// //
// Version: 1.7.0.83525 //
// Web site: https://pascal.chartasoftware.com/ //
// //
// This code and information are provided "as is" without warranty of //
// any kind. Dissemination of this information or reproduction of //
// this material is strictly forbidden unless prior written permission //
// is obtained from Charta Software B.V.. //
// //
///////////////////////////////////////////////////////////////////////////
unit Hash.Algorithm;
interface
uses
Byte.Block,
Integer._32,
Integer._32.Positive,
Integer._64.Positive,
Memory.Block,
Stream.Input,
Stream.Output;
type
THashAlgorithmClass = class of THashAlgorithm;
THashAlgorithm = class(TOutputStream)
private
Buffer: TMemoryBlock;
BufferStream: TOutputStream;
Size: TPositiveInteger64;
Index: TPositiveInteger32;
protected
procedure Compress(Stream: TInputStream); virtual; abstract;
procedure WriteHash(Stream: TOutputStream); virtual; abstract;
procedure WriteSize(Stream: TOutputStream; Size: TPositiveInteger64); virtual; abstract;
procedure Initialize(); virtual;
procedure Finalize(); virtual;
procedure AssignFrom(Source: THashAlgorithm); virtual;
procedure CompressBuffer();
protected
class function GetByteCountForSize(): TPositiveInteger32; virtual; abstract;
public
constructor Create(); virtual;
destructor Destroy(); override;
procedure Write(const Buffer; Count: TPositiveInteger32); override;
function Copy(): THashAlgorithm; virtual; abstract;
function Digest(): TMemoryBlock;
public
class function GetHashSize(): TInteger32; virtual; abstract;
class function GetBlockSize(): TInteger32; virtual; abstract;
class function Compute(Input: TByteBlock): TMemoryBlock;
end;
implementation
uses
Byte,
Mathematics,
Memory.Block.Physical;
{ THashAlgorithm }
procedure THashAlgorithm.AssignFrom(Source: THashAlgorithm);
begin
Buffer.AssignFrom(Source.Buffer);
Size := Source.Size;
Index := Source.Index;
BufferStream.Free();
BufferStream := Buffer.CreateCircularOverwriteStream(Index);
end;
procedure THashAlgorithm.CompressBuffer();
var
Stream: TInputStream;
begin
Stream := Buffer.CreateInputStream();
Compress(Stream);
Stream.Free();
end;
class function THashAlgorithm.Compute(Input: TByteBlock): TMemoryBlock;
var
Algorithm: THashAlgorithm;
begin
Algorithm := Create();
Input.Write(Algorithm);
Result := Algorithm.Digest();
Algorithm.Free();
end;
constructor THashAlgorithm.Create();
begin
inherited Create();
Buffer := TPhysicalMemoryBlock.Create(GetBlockSize());
Initialize();
end;
procedure THashAlgorithm.Finalize();
begin
BufferStream.WriteLittleEndian8($80);
Inc(Index);
if Index > Buffer.Size - GetByteCountForSize() then
begin
BufferStream.WriteZeros(Buffer.Size - Index);
CompressBuffer();
Index := 0;
end;
BufferStream.WriteZeros(Buffer.Size - GetByteCountForSize() - Index);
WriteSize(BufferStream, Size * 8);
CompressBuffer();
end;
procedure THashAlgorithm.Initialize();
begin
BufferStream.Free();
Index := 0;
Size := 0;
BufferStream := Buffer.CreateCircularOverwriteStream();
end;
destructor THashAlgorithm.Destroy();
begin
BufferStream.Free();
Buffer.Free();
inherited Destroy();
end;
function THashAlgorithm.Digest(): TMemoryBlock;
var
Stream: TOutputStream;
begin
Finalize();
Result := TPhysicalMemoryBlock.Create(GetHashSize());
Stream := Result.CreateOverwriteStream();
WriteHash(Stream);
Stream.Free();
Initialize();
end;
procedure THashAlgorithm.Write(const Buffer; Count: TPositiveInteger32);
var
Source: PByte;
WrittenCount: TPositiveInteger32;
ToWriteCount: TPositiveInteger32;
begin
Inc(Size, Count);
Source := PByte(@Buffer);
WrittenCount := 0;
while WrittenCount < Count do
begin
ToWriteCount := Minimum(Count - WrittenCount, Self.Buffer.Size - Index);
BufferStream.Write(Source^, ToWriteCount);
Inc(Source, ToWriteCount);
Inc(Index, ToWriteCount);
Inc(WrittenCount, ToWriteCount);
if Index = Self.Buffer.Size then
begin
Index := 0;
CompressBuffer();
end;
end;
end;
end.
|