大家帮忙看下以下代码实现的是什么加密算法?
char* bstr =
"ABCDEFGHIJKLMNOPQ"
"RSTUVWXYZabcdefgh"
"ijklmnopqrstuvwxy"
"z0123456789+/";
char rstr[] = {
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, 0, 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};
void encode(const char* input,size_t l,string& output, bool add_crlf)
{
size_t i = 0;
size_t o = 0;
output = "";
while (i < l)
{
size_t remain = l - i;
if (add_crlf && o && o % 76 == 0)
output += "\n";
switch (remain)
{
case 1:
output += bstr[ ((input[i] >> 2) & 0x3f) ];
output += bstr[ ((input[i] << 4) & 0x30) ];
output += "==";
break;
case 2:
output += bstr[ ((input[i] >> 2) & 0x3f) ];
output += bstr[ ((input[i] << 4) & 0x30) + ((input[i + 1] >> 4) & 0x0f) ];
output += bstr[ ((input[i + 1] << 2) & 0x3c) ];
output += "=";
break;
default:
output += bstr[ ((input[i] >> 2) & 0x3f) ];
output += bstr[ ((input[i] << 4) & 0x30) + ((input[i + 1] >> 4) & 0x0f) ];
output += bstr[ ((input[i + 1] << 2) & 0x3c) + ((input[i + 2] >> 6) & 0x03) ];
output += bstr[ (input[i + 2] & 0x3f) ];
}
o += 4;
i += 3;
}
}
void decode(const std::string& input,std::string& output)
{
size_t i = 0;
size_t l = input.size();
output = "";
while (i < l)
{
while (i < l && (input[i] == 13 || input[i] == 10))
i++;
if (i < l)
{
char b1 = (char)((rstr[(int)input[i]] << 2 & 0xfc) +
(rstr[(int)input[i + 1]] >> 4 & 0x03));
output += b1;
if (input[i + 2] != '=')
{
char b2 = (char)((rstr[(int)input[i + 1]] << 4 & 0xf0) +
(rstr[(int)input[i + 2]] >> 2 & 0x0f));
output += b2;
}
if (input[i + 3] != '=')
{
char b3 = (char)((rstr[(int)input[i + 2]] << 6 & 0xc0) +
rstr[(int)input[i + 3]]);
output += b3;
}
i += 4;
}
}
}