本篇文章主要介绍了"实现Base64的代码"，对于Linuxjrs看球网直播吧_低调看直播体育app软件下载_低调看体育直播感兴趣的同学可以参考一下：
class Base64
{ public: static string Encrypt(string sPlainText); static string Decrypt(string sCipherText); private: static int ConvertToIndex(unsigned char ucChar); static string Algorithm(unsigned char ucByteHigh, unsigned char ucByteMiddle, unsigned char ucByteLow, unsigned char ucAvailableCount); static char s_caCharSet[64];
}; char Base64::s_caCharSet[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', '+','/' }; int Base64::ConvertToIndex(unsigned char ucChar)
{ if (ucChar == '+') return 62; else if (ucChar == '/') return 63; else if (ucChar == '=') return 0; else if (ucChar >= 'A' && ucChar <= 'Z')
{ return ucChar - 65;
} else if (ucChar >= 'a' && ucChar <= 'z')
{ return ucChar - 97 + 26;
} else if (ucChar >= '0' && ucChar <= '9')
{ return ucChar - 48 + 26 + 26;
} else {
cerr<<"Base64 convert to Index failed"<<endl; return 0; // abort?? }
} /**
* Base64 convert algorithm(from 3 bytes to 4 bytes charset index) */ string Base64::Algorithm(unsigned char ucByteHigh, unsigned char ucByteMiddle, unsigned char ucByteLow, unsigned char ucAvailableCount)
{ string sResult; int iTemp = 0;
unsigned char ucByte1, ucByte2, ucByte3, ucByte4; if (ucAvailableCount == 0) return "";
iTemp = ucByteHigh;
iTemp <<= 8;
iTemp |= ucByteMiddle;
iTemp <<= 8;
iTemp |= ucByteLow;
ucByte4 = iTemp & 0x3F;
ucByte3 = (iTemp & 0xFC0) >> 6;
ucByte2 = (iTemp & 0x3F000) >> 12;
ucByte1 = (iTemp & 0xFC0000) >> 18; if (ucAvailableCount == 1)
{
sResult += s_caCharSet[ucByte1];
sResult += s_caCharSet[ucByte2];
sResult += "==";
} else if (ucAvailableCount == 2)
{
sResult += s_caCharSet[ucByte1];
sResult += s_caCharSet[ucByte2];
sResult += s_caCharSet[ucByte3];
sResult += "=";
} else if (ucAvailableCount == 3)
{
sResult += s_caCharSet[ucByte1];
sResult += s_caCharSet[ucByte2];
sResult += s_caCharSet[ucByte3];
sResult += s_caCharSet[ucByte4];
} else { return "";
} return sResult;
} /**
* sPlainText is plaintext that non encrypted
* return Base64 encrypt text */ string Base64::Encrypt(string sPlainText)
{ string sResult; const unsigned int uPlainTextSize = sPlainText.size(); if (sPlainText.empty())
{
cerr<<"invalid original text"<<endl; return "";
} if (uPlainTextSize == 1)
{ return Algorithm(sPlainText[0], 0, 0, 1);
} else if (uPlainTextSize == 2)
{ return Algorithm(sPlainText[0], sPlainText[1], 0, 2);
} else {
unsigned int i;
unsigned int uCount = uPlainTextSize / 3 * 3; for (i = 0; i < uCount; i+=3)
{ string sTmp = Algorithm(sPlainText[i], sPlainText[i+1], sPlainText[i+2], 3);
sResult += sTmp;
}
unsigned int uMore = uPlainTextSize % 3; if ( uMore != 0)
{ if (uMore == 1)
{
sResult += Algorithm(sPlainText[i], 0, 0, 1);
} else {
sResult += Algorithm(sPlainText[i], sPlainText[i+1], 0, 2);
}
} return sResult;
}
} /**
* input ciphertext and return related plaintext */ string Base64::Decrypt(string sCipherText)
{ string sResult; if (sCipherText.size() % 4 != 0)
{
cerr<<"Invalid parameter, Base64 can't convert from ciphertext to plaintext"<<endl; return "";
} // from high to low unsigned char ucByte1, ucByte2, ucByte3, ucByte4; for (unsigned int i = 0; i < sCipherText.size(); i+=4)
{ string sTmp; int iConvertTo3Bytes = 0;
ucByte1 = ConvertToIndex(sCipherText[i]);
ucByte2 = ConvertToIndex(sCipherText[i+1]);
ucByte3 = ConvertToIndex(sCipherText[i+2]);
ucByte4 = ConvertToIndex(sCipherText[i+3]);
iConvertTo3Bytes = ucByte1;
iConvertTo3Bytes <<= 6;
iConvertTo3Bytes |= ucByte2;
iConvertTo3Bytes <<= 6;
iConvertTo3Bytes |= ucByte3;
iConvertTo3Bytes <<= 6;
iConvertTo3Bytes |= ucByte4;
sTmp = (unsigned char)(iConvertTo3Bytes >> 16);
unsigned char ucTmp = (unsigned char)((iConvertTo3Bytes & 0xFF00) >> 8); if (ucTmp == 0)
{
sResult += sTmp; continue;
} else sTmp += ucTmp;
ucTmp = (unsigned char)(iConvertTo3Bytes & 0xFF); if (ucTmp == 0)
{
sResult += sTmp; continue;
} else sTmp += ucTmp;
sResult += sTmp;
} return sResult;
}
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以上就介绍了实现Base64的代码，包括了方面的内容，希望对Linuxjrs看球网直播吧_低调看直播体育app软件下载_低调看体育直播有兴趣的朋友有所帮助。
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