Rijndael加密。第一个角色很怪异

Question

我正在使用的代码（XE）：

// Encrypt a string and return the Base64 encoded result
function Encrypt(DataToEncrypt: ansistring):ansistring;
const Key: Ansistring = 'keykey';
  KeySize = 32; // 32 bytes = 256 bits
  BlockSize = 16; // 16 bytes = 128 bits
var
  Cipher : TDCP_rijndael;
  Data: ansistring;
  IV: array[0..15] of byte;      // the initialization vector
  i:Integer;
begin
  // Pad Key, IV and Data with zeros as appropriate
  FillChar(IV,Sizeof(IV),0);            // make the IV all zeros

  Data := PadWithZeros(DataToEncrypt,BlockSize);

  for i := 0 to (Length(IV) - 1) do   //just random values for the IV
    IV[i] := Random(256);

  Cipher := TDCP_rijndael.Create(nil);

  if Length(Key) <= 16 then
    Cipher.Init(Key[1],128,@IV[1])
  else if Length(Key) <= 24 then
    Cipher.Init(Key[1],192,@IV[1])
  else
    Cipher.Init(Key[1],256,@IV[1]);
  // Encrypt the data
  Cipher.EncryptCBC(Data[1],Data[1],Length(Data));
  // Free the cipher and clear sensitive information
  Cipher.Free;

  SetString(InitializationVector,PAnsiChar(@IV[1]),Length(IV));  //Save IV
  InitializationVector := Base64EncodeStr(InitializationVector);

  //Base64 encoded result
  Result := Base64EncodeStr(Data);
end;

function Decrypt(IV,Cryptogram:ansistring):ansistring;
const Key: Ansistring = 'keykey';
  KeySize = 32; // 32 bytes = 256 bits
  BlockSize = 16; // 16 bytes = 128 bits
var
  Cipher : TDCP_rijndael;
begin
  if IV='' then
    IV := InitializationVector;

  Cryptogram := Base64DecodeStr(cryptogram);
  // Create the cipher and initialise according to the key length
  cipher := tdcp_rijndael.Create(nil);
  if Length(Key) <= 16 then
    Cipher.Init(Key[1],128,@IV[1])
  else if Length(Key) <= 24 then
    Cipher.Init(Key[1],192,@IV[1])
  else
    Cipher.Init(Key[1],256,@IV[1]);
  // Decrypt the data
  Cipher.DecryptCBC(cryptogram[1],cryptogram[1],Length(cryptogram));
  // Free the cipher and clear sensitive information
  Cipher.Free;
  // Display the result
  Result := cryptogram;
end;

它工作得很好，除非我尝试解密字符串，我得到：

$ C＃$ C'C '＃$B'ÛW' ＃$1F'Ø<™C '＃$8D'Ž' ＃$ 8D'！“MYDATA

所以前几个字母变得非常奇怪。其余部分解密就好了！ 发现类似的问题here，但没有解决方案。 提前谢谢！

Answer 1

对我而言，第一件事就是你在IV的结尾读/写。您将其声明为[0..15]，但是从Cipher.Init和SetString开始，从元素1（！）开始访问所有内容。