谁能帮我把这段代码转换成C#

Question

解密函数，　你参考下面的delphi代码
con1 = 8000;
con2 = 8001;
AesEny = 618;
//解密
function Decrypt(Str:string; Key:Word):String;
var
i,j: Integer;
S, R: AnsiString;
begin
S := AnsiString(Str);
R := '';
for i:=1 to (length(S) div 2 ) do
begin
j := (Integer(S[2*i-1])-65)*26;
j := j+(Integer(S[2*i])-65);
R := R+Ansichar(j);
end;
S := R;
for i:=1 to Length(S) do
begin
R[i] := ansichar(byte(S[i]) xor (Key shr 8));
Key := (byte(S[i])+Key)*Con1+Con2;
end;
Result := String(R);
end;

Answer 1

就是简单的异或加密，直接参照下改写就可以。