字符串加密解密

type
 TDynByteArray = array of byte;
const
 SeedA             = 5678;   /// 常量，你可以修改
 SeedB             = 5432;   /// 常量，你可以修改
/// 对数组加密
function Crypt(const s: TDynByteArray; Key: Word; const bEncrypt: boolean = true): TDynByteArray; overload;
var
 i                 : integer;
begin
 SetLength(Result, Length(s));
 for i := Low(s) to High(s) do
 begin
   Result[i] := s[i] xor (key shr 8);
   if bEncrypt then
     Key := (Result[i] + key) * SeedA + SeedB
   else
     Key := (s[i] + Key) * SeedA + SeedB;
 end;
end;

/// 字符串
function Crypt(const s: string; Key: Word; const bEncrypt: boolean = True): string; overload;
var
 i                 : integer;
 ps, pr            : ^byte;
begin
 SetLength(Result, Length(s));
 ps := @s[1];
 pr := @Result[1];
 for i := 1 to length(s) do
 begin
   pr^ := ps^ xor (Key shr 8);
   if bEncrypt then
     Key := (pr^ + Key) * SeedA + SeedB
   else
     Key := (ps^ + Key) * SeedA + SeedB;
   pr := pointer(integer(pr) + 1);
   ps := pointer(integer(ps) + 1);
 end
end;

/// 也可以对记录进行加密，只要把TResultData改成你的记录类型即可！！！！！！
function Crypt(const s: TResultData; Key: Word; const bEncrypt: boolean = True): TResultData; overload;
var
 i                 : integer;
 ps, pr            : ^byte;
begin
 ps := @s;
 pr := @Result;
 for i := 1 to SizeOf(s) do
 begin
   pr^ := ps^ xor (Key shr 8);
   if bEncrypt then
     Key := (pr^ + Key) * SeedA + SeedB
   else
     Key := (ps^ + Key) * SeedA + SeedB;
   pr := pointer(integer(pr) + 1);
   ps := pointer(integer(ps) + 1);
 end;
end;

//***************************
function cryptstr(const s:string; stype: dword):string;
var
 i: integer;
 fkey: integer;
begin
 result:='';
 case stype of
 0:    
   begin
     randomize;
     fkey := random($ff);
     for i:=1 to length(s) do
      result := result+chr( ord(s[i]) xor i xor fkey);
     result := result + char(fkey);
   end;
 1:    
   begin
     fkey :=  ord(s[length(s)]);
     for i:=1 to length(s) - 1 do
     result := result+chr( ord(s[i]) xor i xor fkey);
  end;
end;