if (Size mod Sizeof(Buffer))<> 0 then
  begin
    read:= Stream.Read(Buffer,Size mod Sizeof(Buffer));
    Update(Buffer,read);
  end;
end;

procedure TDCP_hash.UpdateStr(const Str: string);
begin
  Update(Str[1],Length(Str));
end;

destructor TDCP_hash.Destroy;
begin
  if fInitialized then
    Burn;
  inherited Destroy;
end;


{** TDCP_cipher ***************************************************************}

procedure TDCP_cipher.DeadInt(Value: integer);
begin
end;

procedure TDCP_cipher.DeadStr(Value: string);
begin
end;

class function TDCP_cipher.GetId: integer;
begin
  Result:= -1;
end;

class function TDCP_cipher.GetAlgorithm: string;
begin
  Result:= '';
end;

class function TDCP_cipher.GetMaxKeySize: integer;
begin
  Result:= -1;
end;

class function TDCP_cipher.SelfTest: boolean;
begin
  Result:= false;
end;

procedure TDCP_cipher.Init(const Key; Size: longword; InitVector: pointer);
begin
  if fInitialized then
    Burn;
  if (Size <= 0) or ((Size and 3)<> 0) or (Size> longword(GetMaxKeySize)) then
    raise EDCP_cipher.Create('Invalid key size')
  else
    fInitialized:= true;
end;

procedure TDCP_cipher.InitStr(const Key: string; HashType: TDCP_hashclass);
var
  Hash: TDCP_hash;
  Digest: pointer;
begin
  if fInitialized then
    Burn;
  try
    GetMem(Digest,HashType.GetHashSize div 8);
    Hash:= HashType.Create(Self);
    Hash.Init;
    Hash.UpdateStr(Key);
    Hash.Final(Digest^);
    Hash.Free;
    if MaxKeySize< HashType.GetHashSize then
      Init(Digest^,MaxKeySize,nil)
    else
      Init(Digest^,HashType.GetHashSize,nil);
    FillChar(Digest^,HashType.GetHashSize div 8,$FF);
    FreeMem(Digest);
  except
    raise EDCP_cipher.Create('Unable to allocate sufficient memory for hash digest');
  end;
end;

procedure TDCP_cipher.Burn;
begin
  fInitialized:= false;
end;

procedure TDCP_cipher.Reset;
begin
end;

procedure TDCP_cipher.Encrypt(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_cipher.Decrypt(const Indata; var Outdata; Size: longword);
begin
end;

function TDCP_cipher.EncryptStream(InStream, OutStream: TStream; Size: longword): longword;
var
  Buffer: array[0..8191] of byte;
  i, Read: longword;
begin
  Result:= 0;
  for i:= 1 to (Size div Sizeof(Buffer)) do
  begin
    Read:= InStream.Read(Buffer,Sizeof(Buffer));
    Inc(Result,Read);
    Encrypt(Buffer,Buffer,Read);
    OutStream.Write(Buffer,Read);
  end;
  if (Size mod Sizeof(Buffer))<> 0 then
  begin
    Read:= InStream.Read(Buffer,Size mod Sizeof(Buffer));
    Inc(Result,Read);
    Encrypt(Buffer,Buffer,Read);
    OutStream.Write(Buffer,Read);
  end;
end;

function TDCP_cipher.DecryptStream(InStream, OutStream: TStream; Size: longword): longword;
var
  Buffer: array[0..8191] of byte;
  i, Read: longword;
begin
  Result:= 0;
  for i:= 1 to (Size div Sizeof(Buffer)) do
  begin
    Read:= InStream.Read(Buffer,Sizeof(Buffer));
    Inc(Result,Read);
    Decrypt(Buffer,Buffer,Read);
    OutStream.Write(Buffer,Read);
  end;
  if (Size mod Sizeof(Buffer))<> 0 then
  begin
    Read:= InStream.Read(Buffer,Size mod Sizeof(Buffer));
    Inc(Result,Read);
    Decrypt(Buffer,Buffer,Read);
    OutStream.Write(Buffer,Read);
  end;
end;

function TDCP_cipher.EncryptString(const Str: string): string;
begin
  SetLength(Result,Length(Str));
  Encrypt(Str[1],Result[1],Length(Str));
  Result:= Base64EncodeStr(Result);
end;

function TDCP_cipher.DecryptString(const Str: string): string;
begin
  Result:= Base64DecodeStr(Str);
  Decrypt(Result[1],Result[1],Length(Result));
end;

constructor TDCP_cipher.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  Burn;
end;

destructor TDCP_cipher.Destroy;
begin
  if fInitialized then
    Burn;
  inherited Destroy;
end;


{** TDCP_blockcipher **********************************************************}

procedure TDCP_blockcipher.InitKey(const Key; Size: longword);
begin
end;

class function TDCP_blockcipher.GetBlockSize: integer;
begin
  Result:= -1;
end;

procedure TDCP_blockcipher.SetIV(const Value);
begin
end;

procedure TDCP_blockcipher.GetIV(var Value);
begin
end;

procedure TDCP_blockcipher.Encrypt(const Indata; var Outdata; Size: longword);
begin
  case fCipherMode of
    cmCBC: EncryptCBC(Indata,Outdata,Size);
    cmCFB8bit: EncryptCFB8bit(Indata,Outdata,Size);
    cmCFBblock: EncryptCFBblock(Indata,Outdata,Size);
    cmOFB: EncryptOFB(Indata,Outdata,Size);
    cmCTR: EncryptCTR(Indata,Outdata,Size);
  end;
end;

function TDCP_blockcipher.EncryptString(const Str: string): string;
begin
  SetLength(Result,Length(Str));
  EncryptCFB8bit(Str[1],Result[1],Length(Str));
  Result:= Base64EncodeStr(Result);
end;

function TDCP_blockcipher.DecryptString(const Str: string): string;
begin
  Result:= Base64DecodeStr(Str);
  DecryptCFB8bit(Result[1],Result[1],Length(Result));
end;

procedure TDCP_blockcipher.Decrypt(const Indata; var Outdata; Size: longword);
begin
  case fCipherMode of
    cmCBC: DecryptCBC(Indata,Outdata,Size);
    cmCFB8bit: DecryptCFB8bit(Indata,Outdata,Size);
    cmCFBblock: DecryptCFBblock(Indata,Outdata,Size);
    cmOFB: DecryptOFB(Indata,Outdata,Size);
    cmCTR: DecryptCTR(Indata,Outdata,Size);
  end;
end;

procedure TDCP_blockcipher.EncryptECB(const Indata; var Outdata);
begin
end;

procedure TDCP_blockcipher.DecryptECB(const Indata; var Outdata);
begin
end;

procedure TDCP_blockcipher.EncryptCBC(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.DecryptCBC(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.EncryptCFB8bit(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.DecryptCFB8bit(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.EncryptCFBblock(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.DecryptCFBblock(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.EncryptOFB(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.DecryptOFB(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.EncryptCTR(const Indata; var Outdata; Size: longword);
begin
end;

procedure TDCP_blockcipher.DecryptCTR(const Indata; var Outdata; Size: longword);
begin
end;

constructor TDCP_blockcipher.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  fCipherMode:= cmCBC;
end;


{** Helpher functions *********************************************************}
procedure XorBlock(var InData1, InData2; Size: longword);
var
  i: longword;
begin
  for i:= 1 to Size do
    Pbyte(longword(@InData1)+i-1)^:= Pbyte(longword(@InData1)+i-1)^ xor Pbyte(longword(@InData2)+i-1)^;
end;

end.