unit piStrCrypt;

interface

uses
  Classes;

const
  C1 = 52845;
  C2 = 22719;

function StrEncrypt( S: String; Key: Word): String;
function StrDecrypt( S: String; Key: Word): String;

implementation

//加密字符串
function StrEncrypt( S: String; Key: Word): String;
var
 I: Integer;
 j: Integer;
begin
 Result := S;
 for I := 1 to Length(S) do
 begin
  Result[I] := char(byte(S[I]) xor (Key shr 8));
  Key := (byte(Result[I]) + Key) * C1 + C2;
 end;
 s:=Result;
 Result:='';
 for i:=1 to length(s) do
 begin
  j:=Integer(s[i]);
  Result:=Result + Char(65+(j div 26))+Char(65+(j mod 26));
 end;
end;

//解密字符串
function StrDecrypt( S: String; Key: Word): String;
var
 I: Integer;
 j: Integer;
begin
 result:='';
 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);
  result:=result + Char(j);
 end;
 s:=result;
 for I := 1 to Length(S) do
 begin
  Result[I] := char(byte(S[I]) xor (Key shr 8));
  Key := (byte(S[I]) + Key) * C1 + C2;
 end;
end;
//Memo1.Text:=StrEncrypt(Memo2.Text,123);
end.