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[Master674]

Is there a safe and easy crypting method to crypt stuff server side (PHP implementation) and decrypt it clientside (C++ implementation)??

Hey, I'm trying to decrypt some data via RC4 (Data is sent by a Webserver). But if I try to decrypt it sometimes the string is cut off at some random location! I thought it maybe is a unicode null terminator when the RC4 output is generated so i put a base64 function over the Webserver result.

I use following decrypt functions:

void rc4( const wchar_t *data, const wchar_t *key, wchar_t **output )

{

	wchar_t *temp;

	unsigned int i,j=0,t,tmp,tmp2,s[256], k[256];

	for (tmp=0;tmp<256;tmp++)

	{

		s[tmp]=tmp;

		k[tmp]=key[(tmp % wcslen(key))];

	}

	for (i=0;i<256;i++)

	{

		j = (j + s[i] + k[i]) % 256;

		tmp=s[i];

		s[i]=s[j];

		s[j]=tmp;

	}

	temp = new wchar_t[wcslen(data) + 1];

	i=j=0;

	for (tmp=0;tmp<wcslen(data);tmp++)

	{

		i = (i + 1) % 256;

		j = (j + s[i]) % 256;

		tmp2=s[i];

		s[i]=s[j];

		s[j]=tmp2;

		t = (s[i] + s[j]) % 256;

		if (s[t]==data[tmp])

			temp[tmp]=data[tmp];

		else

			temp[tmp]=s[t]^data[tmp];

	}


	temp[tmp] = '\0';

	*output = temp;

}


static const std::wstring base64_chars = 

             L"ABCDEFGHIJKLMNOPQRSTUVWXYZ"

             L"abcdefghijklmnopqrstuvwxyz"

             L"0123456789+/";


static inline bool is_base64(wchar_t c) {

  return (isalnum(c) || (c == '+') || (c == '/'));

}


void base64_decode(const wchar_t *encoded_string, wchar_t **output)

{

  unsigned int in_len = wcslen( encoded_string );

  unsigned int i = 0;

  unsigned int j = 0;

  unsigned int in_ = 0;

  unsigned int r = 0;

  wchar_t char_array_4[4], char_array_3[3];

  wchar_t *ret;

  ret = new wchar_t[in_len + 1];


  while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {

    char_array_4[i++] = encoded_string[in_]; in_++;

    if (i ==4) {

      for (i = 0; i <4; i++)

        char_array_4[i] = base64_chars.find(char_array_4[i]);


      char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);

      char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);

      char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];


      for (i = 0; (i < 3); i++, r++)

        ret[r] = char_array_3[i];

      i = 0;

    }

  }


  if (i) {

    for (j = i; j <4; j++)

      char_array_4[j] = 0;


    for (j = 0; j <4; j++)

      char_array_4[j] = base64_chars.find(char_array_4[j]);


    char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);

    char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);

    char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];


    for (j = 0; (j < i - 1); j++, r++)

		ret[r] = char_array_3[j];

  }


  ret[r++] = '\0';

  *output = ret;

  //return ret;

}

As you can see I'm using unsigned chars here. So my question is: Can a unsigned char hold any byte produced by a RC4 function?

Is there a safe and easy crypting method to crypt stuff server side (PHP implementation) and decrypt it clientside (C++ implementation)??

If i need to use widestrings here, how would i need to change the above functions?

---------- Post added at 09:25 AM ---------- Previous post was at 08:05 AM ----------

I have changed everything to wchar_t now. Still no result.