DELPHI加密字串（异或运算加密）

首先有两个自定的转换函数：  
 
function myStrToHex(s:string):string; //字串转16进制
var
  TmpStr:string;
  i:integer;
begin
  TmpStr:='';
  for i:=1 to Length(s)do
    TmpStr:=TmpStr+IntToHex(ord(s[i]),2);
  Result:=TmpStr;
end;    
 
function myHexToStr(S:string):string; //16进制转字串
var
  HexS,TmpStr:string;
  i:Integer;
  a:Byte;
begin
  HexS:=s;
  if Length(HexS) mod 2=1 then
    HexS:=HexS+'0';
  TmpStr:='';
  for i:=1 to(Length(HexS)div 2)do
  begin
    a:=StrToInt('$'+HexS[2*i-1]+HexS[2*i]);
    TmpStr:=TmpStr+Chr(a);
  end;
  Result:=TmpStr;
end;
function myStrToHex(s:string):string; //字串转16进制
var
  TmpStr:string;
  i:integer;
begin
  TmpStr:='';
  for i:=1 to Length(s)do
    TmpStr:=TmpStr+IntToHex(ord(s[i]),2);
  Result:=TmpStr;
end;  
 
function myHexToStr(S:string):string; //16进制转字串
var
  HexS,TmpStr:string;
  i:Integer;
  a:Byte;
begin
  HexS:=s;
  if Length(HexS) mod 2=1 then
    HexS:=HexS+'0';
  TmpStr:='';
  for i:=1 to(Length(HexS)div 2)do
  begin
    a:=StrToInt('$'+HexS[2*i-1]+HexS[2*i]);
    TmpStr:=TmpStr+Chr(a);
  end;
  Result:=TmpStr;
end;   
 
然后就是加密、解密函数了：  
 
{两个函数的参数相同，s为要加密、解密的字串；sKey为密匙}
function EncryptStr(const s:string;sKey:string):string; //加密
var
  i,j:Integer;
  HexS,HexsKey,MidS,TmpStr:string;
  a,b,c:byte;
begin
  HexS:=myStrToHex(s);
  HexsKey:=myStrToHex(sKey);
  MidS:=HexS;
  for i:=1 to(Length(HexsKey)div 2)do
  begin
    if i<>1 then MidS:=TmpStr;
    TmpStr:=''; //下面要用到TmpStr，所以要清空
    for j:=1 to (Length(MidS)div 2)do
    begin
      a:=StrToInt('$'+midS[2*j-1]+midS[2*j]);
      b:=StrToInt('$'+HexsKey[2*i-1]+HexsKey[2*i]);
      c:=a xor b;
      tmpstr:=TmpStr+myStrToHex(Chr(c));
    end;
  end;
  Result:=TmpStr;
end;    
 
function DecryptStr(const s:string;sKey:string):string; //解密
var
  i,j:Integer;
  HexS,HexsKey,MidS,TmpStr:string;
  a,b,c:Byte;
begin
  HexS:=s;
  if Length(HexS)mod 2=1 then //检查是否为字符串
  begin
    ShowMessage('密文错误！');
    Exit;
  end;
  HexsKey:=myStrToHex(sKey);
  TmpStr:=HexS;
  MidS:=HexS;
  for i:=(length(HexsKey) div 2) downto 1 do
  begin
    if i<>(length(HexsKey) div 2)then
      MidS:=TmpStr;
    TmpStr:=''; //下面要用到TmpStr，所以要清空
    for j:=1 to(length(MidS) div 2)do
    begin
      a:=StrToInt('$'+MidS[2*j-1]+MidS[2*j]);
      b:=StrToInt('$'+HexsKey[2*i-1]+HexsKey[2*i]);
      c:=a xor b;
      TmpStr := TmpStr+myStrToHex(Chr(c));
    end;
  end;
    Result:=myHexToStr(TmpStr);
end;
{两个函数的参数相同，s为要加密、解密的字串；sKey为密匙}
function EncryptStr(const s:string;sKey:string):string; //加密
var
  i,j:Integer;
  HexS,HexsKey,MidS,TmpStr:string;
  a,b,c:byte;
begin
  HexS:=myStrToHex(s);
  HexsKey:=myStrToHex(sKey);
  MidS:=HexS;
  for i:=1 to(Length(HexsKey)div 2)do
  begin
    if i<>1 then MidS:=TmpStr;
    TmpStr:=''; //下面要用到TmpStr，所以要清空
    for j:=1 to (Length(MidS)div 2)do
    begin
      a:=StrToInt('$'+midS[2*j-1]+midS[2*j]);
      b:=StrToInt('$'+HexsKey[2*i-1]+HexsKey[2*i]);
      c:=a xor b;
      tmpstr:=TmpStr+myStrToHex(Chr(c));
    end;
  end;
  Result:=TmpStr;
end;  
 
function DecryptStr(const s:string;sKey:string):string; //解密
var
  i,j:Integer;
  HexS,HexsKey,MidS,TmpStr:string;
  a,b,c:Byte;
begin
  HexS:=s;
  if Length(HexS)mod 2=1 then //检查是否为字符串
  begin
    ShowMessage('密文错误！');
    Exit;
  end;
  HexsKey:=myStrToHex(sKey);
  TmpStr:=HexS;
  MidS:=HexS;
  for i:=(length(HexsKey) div 2) downto 1 do
  begin
    if i<>(length(HexsKey) div 2)then
      MidS:=TmpStr;
    TmpStr:=''; //下面要用到TmpStr，所以要清空
    for j:=1 to(length(MidS) div 2)do
    begin
      a:=StrToInt('$'+MidS[2*j-1]+MidS[2*j]);
      b:=StrToInt('$'+HexsKey[2*i-1]+HexsKey[2*i]);
      c:=a xor b;
      TmpStr := TmpStr+myStrToHex(Chr(c));
    end;
  end;
    Result:=myHexToStr(TmpStr);
end;   
 
现在已经可以使用了，调用EncryptStr和DecryptStr分别加密、解密  
 
例：  
 
[delphi] view plaincopyprint?Edit1.Text:=EncryptStr('Hello','delphi');    
 
////////////////////////////////////////     
 
Edit1.Text:=DecryptStr(Edit1.Text,'delphi');
Edit1.Text:=EncryptStr('Hello','delphi');  
 
////////////////////////////////////////  
 
Edit1.Text:=DecryptStr(Edit1.Text,'delphi');