MatasanoCrypto/utils/hex_to_base64.cpp

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MIN(a,b) a<b ? a : b

unsigned short char_to_hex[256] = { 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
	// 50
	0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
	0x0f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0a, 0x0b, 0x0c,
    0x0d, 0x0e, 0x0f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

	// 100: this rest shouldn't be needed 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

unsigned char int_to_base64[65] = {
	'A','B','C','D','E','F','G','H','I','J',
	'K','L','M','N','O','P','Q','R','S','T',
	'U','V','W','X','Y','Z','a','b','c','d',
	'e','f','g','h','i','j','k','l','m','n',
	'o','p','q','r','s','t','u','v','w','x',
	'y','z','0','1','2','3','4','5','6','7',
	'8','9','+','/','='
};

// data stores 24 bits
struct int24 {
	unsigned int data:24;
};

void convert_string_to_hex(const char* const iArray, const unsigned iArrayLen, unsigned char*& oHexArray)
{
	unsigned char hex;
	for(unsigned long i=0; i<iArrayLen; i+=2)
	{
		hex  = char_to_hex[ iArray[i  ] ] * 16;
		hex += char_to_hex[ iArray[i+1] ];

		oHexArray[i/2]=hex;
	}	
}

void convert_hex_to_string(const unsigned char* const iHexArray, unsigned iHexArrayLen, char*& oStringBuf )
{
	for(unsigned i=0; i<iHexArrayLen; i++)
	{	
		sprintf(oStringBuf+(i*2), "%x", iHexArray[i]);
	}
}

void read_bytes(const char* hex_buff, int24& o_data, unsigned len=3)
{
	unsigned char* tmp = (unsigned char*)malloc(len);
	convert_string_to_hex(hex_buff, len*2, tmp);
	for(unsigned i=0; i<len; ++i)
	{
		o_data.data <<= 8;
		o_data.data |= tmp[i];
	}
	free(tmp);
}

/* -----------------------------------------------------------------------------
 * @brief   Converts HEX to Base64      
 *          
 * @param   hex_buf     : 	buffer with hexes to be converted
 *			base64_buff :	output buffer. has to be \0 initialized
 *			hex_buff_len: 	length of hex_buff
 *          
 * @returns number of characters written to base64_buf
 *
 * @remarks remarks 
 *
 *------------------------------------------------------------------------------ */
unsigned hex_to_base64(const char* hex_buff, char*& base64_buff, unsigned hex_buff_len ) 
{		
	unsigned j=0;
	const unsigned unaligned = hex_buff_len % 6;	
	unsigned len_aligned = hex_buff_len - unaligned;

	int24 data;
	unsigned char idx1,idx2,idx3,idx4;
	for(unsigned i=0; i<len_aligned; i+=6) 
	{
		data.data = 0;
		read_bytes(hex_buff+i, data, 3);

		idx1 = 0x3F & (data.data >> 6*3);
		idx2 = 0x3F & (data.data >> 6*2);
		idx3 = 0x3F & (data.data >> 6);
		idx4 = 0x3F & data.data;

		base64_buff[j++] = int_to_base64[idx1];
		base64_buff[j++] = int_to_base64[idx2];
		base64_buff[j++] = int_to_base64[idx3];
		base64_buff[j++] = int_to_base64[idx4];
	}

	if(unaligned)
	{
		const unsigned rest_bytes = unaligned/2;
		data.data = 0;
		read_bytes(hex_buff+len_aligned, data, rest_bytes);

		if(rest_bytes==1)
		{
			if( ( data.data & (data.data & 0x3F) ) == data.data)
			{
				base64_buff[j++] = int_to_base64[ data.data ];	
			}
			else
			{
				idx1 =(data.data >> 2 ) & 0x3F;
				idx2 = data.data & 0x3;
				base64_buff[j++] = int_to_base64[ idx1 ];
				base64_buff[j++] = int_to_base64[ idx2 ];
			}
		}
		else if(rest_bytes==2)
		{
			idx1 =(data.data >> 10 ) & 0x3F;
			idx2 =(data.data >>  4 ) & 0x3F;
			idx3 =(data.data ) & 15;

			base64_buff[j++] = int_to_base64[ idx1 ];
			base64_buff[j++] = int_to_base64[ idx2 ];
			base64_buff[j++] = int_to_base64[ idx3 ];
		}
	}
	return j;
}


/* -----------------------------------------------------------------------------
 * @brief   xor_strings      
 *          
 * @param   iLeftString : String of HEX numbers. Length of string needs to be even
 * @param	iRightString: Second string. Has to be same length as iLeftString
 * @param	oXorArray   : Array will keep result of XOR. Array needs to be pre
 *						  allocated with length at least strlen(iLeftString)/2
 *          
 * @remarks remarks 
 *
-------------------------------------------------------------------------------- */
void xor_strings(const char* const iLeftString, const char* const iRightString, unsigned char*& oXorArray)
{
	const size_t aInLen = strlen(iLeftString);
	
	// Both arrays need to have same length
	if(strlen(iRightString) != aInLen) return;
	
	// Length of both tables needs to be even
	if(aInLen % 2 != 0) return;

	unsigned char* xor_array1 = (unsigned char*)malloc( aInLen );
	unsigned char* xor_array2 = (unsigned char*)malloc( aInLen );

	convert_string_to_hex(iLeftString, aInLen, xor_array1);
	convert_string_to_hex(iRightString, aInLen, xor_array2);

	for(size_t i=0; i<aInLen/2; ++i) {
		oXorArray[i] = xor_array1[i] ^ xor_array2[i];
	}

	free(xor_array1);
	free(xor_array2);
}