Delphi关于改进AES算法的加解密文件功能

function StrToHex(Value: string): string;

var

I: Integer;

begin

Result := '';

for I := 1 to Length(Value) do

Result := Result + IntToHex(Ord(Value[I]), 2);

end;

function EncryptString(Value: string; Key: string): string;

var

SS, DS: TStringStream;

Size: Int64;

AESKey256: TAESKey256;

begin

Result := '';

SS := TStringStream.Create(Value);

DS := TStringStream.Create('');

try

Size := SS.Size;

DS.WriteBuffer(Size, SizeOf(Size));

FillChar(AESKey256, SizeOf(AESKey256), 0 );

Move(PChar(Key)^, AESKey256, Min(SizeOf(AESKey256), Length(Key)));

EncryptAESStreamECB(SS, 0, AESKey256, DS);

Result := StrToHex(DS.DataString);

finally

SS.Free;

DS.Free;

end;

end;

function HexToStr(Value: string): string;

var

I: Integer;

begin

Result := '';

for I := 1 to Length(Value) do

begin

if ((I mod 2) = 1) then

Result := Result + Chr(StrToInt('0x'+ Copy(Value, I, 2)));

end;

end;

function DecryptString(Value: string; Key: string): string;

var

SS, DS: TStringStream;

Size: Int64;

AESKey256: TAESKey256;

begin

Result := '';

SS := TStringStream.Create(HexToStr(Value));

DS := TStringStream.Create('');

try

Size := SS.Size;

SS.ReadBuffer(Size, SizeOf(Size));

FillChar(AESKey256, SizeOf(AESKey256), 0 );

Move(PChar(Key)^, AESKey256, Min(SizeOf(AESKey256), Length(Key)));

DecryptAESStreamECB(SS, SS.Size - SS.Position, AESKey256, DS);

Result := DS.DataString;

finally

SS.Free;

DS.Free;

end;

end;

// ---------- 文件加密函数 按照 256 位密匙加密

procedure TSysClass.EncryptFile(SourceFile, DestFile: string;Key: string);

var

SFS, DFS: TFileStream;

Size: Int64;

AESKey256: TAESKey256;

info:string;

begin

SFS := TFileStream.Create(SourceFile, fmOpenRead);

try

DFS := TFileStream.Create(DestFile, fmCreate);

try

//-----------------------------文件解密部分---------------------------------

Size := SFS.Size;

DFS.WriteBuffer(Size, SizeOf(Size));

FillChar(AESKey256, SizeOf(AESKey256), 0 );

Move(PChar(Key)^, AESKey256, Min(SizeOf(AESKey256), Length(Key)));

EncryptAESStreamECB(SFS, 0, AESKey256, DFS);

//-----------------------------在文件尾部加入判断解密是否成功的信息----------

info:=EncryptString('123456789',Key);

DFS.Seek(0,soFromEnd);

DFS.Write(Info[1],60);//往后面写入60个字符，其中有一些保留没有使用

finally

DFS.Free;

end;

finally

SFS.Free;

end;

end;

// ---------- 文件解密函数 按照 256 位密匙解密

Function TSysClass.DecryptFile(SourceFile, DestFile: string;Key: string):boolean;

var

Test, DFS: TFileStream;

SFS:TMemoryStream;

Size: Int64;

AESKey256: TAESKey256;

Info:string;

begin

SetLength(Info,60);

//----------------------------------------先检测文件解密是否正确-------------------

Test := TFileStream.Create(SourceFile, fmOpenRead);

try

Test.Seek(-60,soFromEnd);

Test.Read(Info[1],60);

//-----------------------------判断密码是否正确，如果错误

if AnsiContainsStr(Trim(info),EncryptString('123456789',Key)) = false then begin

result:=false;//解密失败

Test.Free;//释放流

exit;

end;

//-----------------------------如果密码正确,取得实际文件的内容

Test.Seek(0,soFromBeginning);

SFS:=TMemoryStream.Create;

SFS.CopyFrom(Test,Test.Size-60);

Test.Free;

except //-----------------------如果出现异常不能打开文件

SFS.Free;

Test.Free;

result:=false;

exit;

end;

//-------------------------------正式开始解密

SFS.Position:=0;

SFS.ReadBuffer(Size, SizeOf(Size));

DFS := TFileStream.Create(DestFile, fmCreate);

FillChar(AESKey256, SizeOf(AESKey256), 0 );

Move(PChar(Key)^, AESKey256, Min(SizeOf(AESKey256), Length(Key)));

DecryptAESStreamECB(SFS, SFS.Size - SFS.Position, AESKey256, DFS);

DFS.Size := Size;

DFS.Free;

SFS.Free;

result:=true;

end;

//-----------------------【加密解密基础函数】----------------------------------------------------