Base64 编解码工具

/* create by cx 2016/12/15 */ #include "Base64.h" static const char encode_map[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; static char decode_map[256]; static void initBase64DecodeMap() { memset(decode_map, -1, sizeof(decode_map)); for (int i = 'A'; i <= 'Z'; i++) decode_map[i] = 0 + (i - 'A'); for (int i = 'a'; i <= 'z'; i++) decode_map[i] = 26 + (i - 'a'); for (int i = '0'; i <= '9'; ++i) decode_map[i] = 52 + (i - '0'); decode_map[(unsigned char)'+'] = 62; decode_map[(unsigned char)'/'] = 63; decode_map[(unsigned char)'='] = 0; } bool CBase64::Encode(const string& strIn, string& strOut) { size_t nInLen = strIn.length(); size_t numOrig24BitValues = nInLen / 3; bool havePadding = (nInLen != numOrig24BitValues * 3); bool havePadding2 = (nInLen == numOrig24BitValues * 3 + 1); size_t numResultBytes = 4 * (numOrig24BitValues + havePadding); strOut.clear(); for (size_t i = 0; i < numOrig24BitValues; ++i) { strOut.append(1, encode_map[(strIn[3 * i] >> 2) & 0x3F]); strOut.append(1, encode_map[((strIn[3 * i] << 4) & 0x30) | ((strIn[3 * i + 1] >> 4) & 0x0F)]); strOut.append(1, encode_map[((strIn[3 * i + 1] << 2) & 0x3C) | ((strIn[3 * i + 2] >> 6) & 0x03)]); strOut.append(1, encode_map[strIn[3 * i + 2] & 0x3F]); } if (havePadding) { size_t i = numOrig24BitValues; strOut.append(1, encode_map[(strIn[3 * i] >> 2) & 0x3F]); if (havePadding2) { strOut.append(1, encode_map[((strIn[3 * i] << 4) & 0x30) | ((strIn[3 * i + 1] >> 4) & 0x0F)]); strOut.append(1, '='); } else { strOut.append(1, encode_map[((strIn[3 * i] << 4) & 0x30) | ((strIn[3 * i + 1] >> 4) & 0x0F)]); strOut.append(1, encode_map[((strIn[3 * i + 1] << 2) & 0x3C) | ((strIn[3 * i + 2] >> 6) & 0x03)]); } strOut.append(1, '='); } return true; } bool CBase64::Decode(const string& strIn, string& strOut, bool fCheckInputValid/* = false*/) { size_t nInlen = strIn.length(); if (nInlen < 4 || (nInlen % 4) != 0) { return false; } static bool bInit = false; if (!bInit) { initBase64DecodeMap(); bInit = true; } if (fCheckInputValid) { for (size_t i = 0; i < nInlen; ++i) { if (decode_map[(unsigned char)strIn[i]] == -1) { return false; } } } size_t nOutLen = (nInlen * 3) / 4; string strTmpOut; strTmpOut.resize(nOutLen); size_t nLoopLen = nOutLen / 3; for (size_t i = 0; i < nLoopLen; ++i) { strTmpOut[i * 3] = ((decode_map[strIn[i * 4]] << 2) & 0xFC) | ((decode_map[strIn[i * 4 + 1]] >> 4) & 0x03); strTmpOut[i * 3 + 1] = ((decode_map[strIn[i * 4 + 1]] << 4) & 0xF0) | ((decode_map[strIn[i * 4 + 2]] >> 2) & 0x0F); strTmpOut[i * 3 + 2] = ((decode_map[strIn[i * 4 + 2]] << 6) & 0xC0) | (decode_map[strIn[i * 4 + 3]] & 0x3F); } if (strIn[nInlen - 1] == '=') { nOutLen--; if (strIn[nInlen - 2] == '=') { nOutLen--; } } const char* pData = strTmpOut.data(); strOut.clear(); strOut.append(pData, pData + nOutLen); return true; }