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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 | template<typename CharT> class base64 { public: //base64 加密 static bool encode (std::basic_string<charT>& _old, std::basic_string<charT>& _new) { static charT _code [] = { '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', '+', '/', }; ptrdiff_t i, len = _old.length (); _new.resize (((len % 3 ? 1 : 0) + len / 3) * 4); //主编码循环 for (i = 0; i < len / 3; ++i) { _new [i * 4] = _code [_old [i * 3] >> 2]; _new [i * 4 + 1] = _code [((_old [i * 3] & 0x03) << 4) | (_old [i * 3 + 1] >> 4)]; _new [i * 4 + 2] = _code [((_old [i * 3 + 1] & 0x0F) << 2) | (_old [i * 3 + 2]) >> 6]; _new [i * 4 + 3] = _code [_old [i * 3 + 2] & 0x3F]; } //长度不为3的倍数 if (len % 3) { //第一字节肯定不会溢出，故不检查边界 _new [i * 4] = _code [_old [i * 3] >> 2]; _new [i * 4 + 1] = _code [((_old [i * 3] & 0x03) << 4) | (i * 3 + 1 < len ? _old [i * 3 + 1] >> 4 : 0)]; //倒数第二位可能为'=' if (1 == len % 3) _new [i * 4 + 2] = '='; else _new [i * 4 + 2] = _code [(i * 3 + 1 < len ? (_old [i * 3 + 1] & 0x0F) << 2 : 0)]; //末位肯定为'=' _new [i * 4 + 3] = '='; } return true; } //base64 解密 static bool decode (std::string& _old, std::string& _new) { static charT _ucode [] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 62, 0, 0, 0, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 0, 0, 0, 64, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 0, 0, 0, 0, 0, 0, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 0, 0, 0, 0, 0, }; ptrdiff_t i, len = _old.length (); ptrdiff_t len2 = len / 4 * 3; //判断末位是否有等号、有几个等号 if ('=' == _old [len - 2]) len2 -= 2; else if ('=' == _old [len - 1]) len2--; else if (len % 4) len2 += (len % 4 - 1); _new.resize (len2); //主解密循环 for (i = 0; i < len2 / 3; ++i) { _new [i * 3] = (_ucode [_old [i * 4]] << 2) | (_ucode [_old [i * 4 + 1]] >> 4); _new [i * 3 + 1] = ((_ucode [_old [i * 4 + 1]] & 0x0F) << 4) | (_ucode [_old [i * 4 + 2]] >> 2); _new [i * 3 + 2] = ((_ucode [_old [i * 4 + 2]] & 0x03) << 6) | (_ucode [_old [i * 4 + 3]]); } //末位为一个或两个等号的情况，这时候不能通过主解密循环进行解密 if (len2 % 3) { _new [i * 3] = (_ucode [_old [i * 4]] << 2) | (_ucode [_old [i * 4 + 1]] >> 4); if (2 == len % 3) _new [i * 3 + 1] = ((_ucode [_old [i * 4 + 1]] & 0x0F) << 4) | (_ucode [_old [i * 4 + 2]] >> 2); } return true; } }; |
