three_to_four (char *from, char *to)
{
	static const char tab64[64]=
	{
		'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','+','/'
	};

	to[0] = tab64 [ (from[0] >> 2) & 63 ];
	to[1] = tab64 [ ((from[0] << 4) | (from[1] >> 4)) & 63 ];
	to[2] = tab64 [ ((from[1] << 2) | (from[2] >> 6)) & 63 ];
	to[3] = tab64 [ from[2] & 63 ];
};

This weakness pertains to the use of cryptographic functions that are weak, misconfigured, or outdated, which undermines the intended protection of encrypted data and communications.