blob: 324a5ddaba01d4cc4383536cf5700c5ddc0256b0 (
plain)
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
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
#pragma once
#include <cstdint>
#include <stdexcept>
#include <string>
#include <vector>
namespace { namespace base64 {
const static char encodeLookup[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
const static char padCharacter = '=';
std::string encode(const std::vector<uint8_t> & input)
{
std::string encoded;
encoded.reserve(((input.size()/3) + (input.size() % 3 > 0)) * 4);
uint32_t temp;
auto cursor = input.begin();
for (size_t i = 0; i < input.size() / 3; i++)
{
temp = (*cursor++) << 16; // Convert to big endian
temp += (*cursor++) << 8;
temp += (*cursor++);
encoded.append(1, encodeLookup[(temp & 0x00FC0000) >> 18]);
encoded.append(1, encodeLookup[(temp & 0x0003F000) >> 12]);
encoded.append(1, encodeLookup[(temp & 0x00000FC0) >> 6 ]);
encoded.append(1, encodeLookup[(temp & 0x0000003F) ]);
}
switch (input.size() % 3)
{
case 1:
temp = (*cursor++) << 16; // Convert to big endian
encoded.append(1, encodeLookup[(temp & 0x00FC0000) >> 18]);
encoded.append(1, encodeLookup[(temp & 0x0003F000) >> 12]);
encoded.append(2, padCharacter);
break;
case 2:
temp = (*cursor++) << 16; // Convert to big endian
temp += (*cursor++) << 8;
encoded.append(1, encodeLookup[(temp & 0x00FC0000) >> 18]);
encoded.append(1, encodeLookup[(temp & 0x0003F000) >> 12]);
encoded.append(1, encodeLookup[(temp & 0x00000FC0) >> 6 ]);
encoded.append(1, padCharacter);
break;
}
return encoded;
}
std::vector<uint8_t> decode(const std::string & input)
{
if (input.length() % 4) // Sanity check
throw std::runtime_error("Non-Valid base64!");
size_t padding = 0;
if (input.length()) {
if (input[input.length() - 1] == padCharacter)
padding++;
if (input[input.length() - 2] == padCharacter)
padding++;
}
// Setup a vector to hold the result
std::vector<uint8_t> decoded;
decoded.reserve(((input.length()/4)*3) - padding);
uint32_t temp = 0; // Holds decoded quanta
auto cursor = input.begin();
while (cursor < input.end())
{
for (size_t quantumPosition = 0; quantumPosition < 4; quantumPosition++)
{
temp <<= 6;
if (*cursor >= 0x41 && *cursor <= 0x5A) // This area will need tweaking if
temp |= *cursor - 0x41; // you are using an alternate alphabet
else if (*cursor >= 0x61 && *cursor <= 0x7A)
temp |= *cursor - 0x47;
else if (*cursor >= 0x30 && *cursor <= 0x39)
temp |= *cursor + 0x04;
else if (*cursor == 0x2B)
temp |= 0x3E; // change to 0x2D for URL alphabet
else if (*cursor == 0x2F)
temp |= 0x3F; // change to 0x5F for URL alphabet
else if (*cursor == padCharacter) // pad
{
switch (input.end() - cursor)
{
case 1: //One pad character
decoded.push_back((temp >> 16) & 0x000000FF);
decoded.push_back((temp >> 8 ) & 0x000000FF);
return decoded;
case 2: //Two pad characters
decoded.push_back((temp >> 10) & 0x000000FF);
return decoded;
default:
throw std::runtime_error("Invalid Padding in Base 64!");
}
} else
throw std::runtime_error("Non-Valid Character in Base 64!");
cursor++;
}
decoded.push_back((temp >> 16) & 0x000000FF);
decoded.push_back((temp >> 8 ) & 0x000000FF);
decoded.push_back((temp ) & 0x000000FF);
}
return decoded;
}
} }
|