There are lots of way can encrypt a text string based on a key. By the approach, you can use a single numerical key, or text string. In terms of security's point of view, text string-based key has better security performance.Below code is an example of string encryption module.
function Encrypt(const InString:string; Salt:string): string; var i : Byte; StartKey, MultKey, AddKey: Word; begin Result := ''; if (Salt = '') then begin Result := InString; end else begin StartKey := Length(Salt); MultKey := Ord(Salt[1]); AddKey := 0; for i := 1 to Length(Salt) - 1 do AddKey := AddKey + Ord(Salt[i]); for i := 1 to Length(InString) do begin Result := Result + CHAR(Byte(InString[i]) xor (StartKey shr 8)); StartKey := (Byte(Result[i]) + StartKey) * MultKey + AddKey; end; end; end; function Decrypt(const InString:string; Salt:string): string; var i : Byte; StartKey, MultKey, AddKey: Word; begin Result := ''; if (Salt = '') then begin Result := InString; end else begin StartKey := Ord(Salt[1]); MultKey := Length(Salt); AddKey := 0; for i := 1 to Length(Salt) - 1 do AddKey := AddKey + Ord(Salt[i]); for i := 1 to Length(InString) do begin Result := Result + CHAR(Byte(InString[i]) xor (StartKey shr 8)); StartKey := (Byte(InString[i]) + StartKey) * MultKey + AddKey; end; end; end;
By the way, above was not helpful for me - I use multibyte character, and below code was so helpful even though I can't use any key on the documentation
uses IdCoder, IdCoderMIME, IdGlobal; .. .. begin // encode string sMasterXML.Text := TIdEncoderMIME.EncodeString(sMasterXML.Text, IndyTextEncoding_UTF8); // deocde string sMasterXML.Text := TIdDecoderMIME.DecodeString(sMasterXML.Text, IndyTextEncoding_UTF8); end;