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
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
| #import "Base64.h"
#import <Availability.h>
#if !__has_feature(objc_arc)
#error This library requires automatic reference counting
#endif
@implementation NSData (Base64)
+ (NSData *)dataWithBase64EncodedString:(NSString *)string
{
const char lookup[] =
{
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 62, 99, 99, 99, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 99, 99, 99, 99, 99, 99,
99, 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, 99, 99, 99, 99, 99,
99, 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, 99, 99, 99, 99, 99
};
NSData *inputData = [string dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
long long inputLength = [inputData length];
const unsigned char *inputBytes = [inputData bytes];
long long maxOutputLength = (inputLength / 4 + 1) * 3;
NSMutableData *outputData = [NSMutableData dataWithLength:maxOutputLength];
unsigned char *outputBytes = (unsigned char *)[outputData mutableBytes];
int accumulator = 0;
long long outputLength = 0;
unsigned char accumulated[] = {0, 0, 0, 0};
for (long long i = 0; i < inputLength; i++)
{
unsigned char decoded = lookup[inputBytes[i] & 0x7F];
if (decoded != 99)
{
accumulated[accumulator] = decoded;
if (accumulator == 3)
{
outputBytes[outputLength++] = (accumulated[0] << 2) | (accumulated[1] >> 4);
outputBytes[outputLength++] = (accumulated[1] << 4) | (accumulated[2] >> 2);
outputBytes[outputLength++] = (accumulated[2] << 6) | accumulated[3];
}
accumulator = (accumulator + 1) % 4;
}
}
//handle left-over data
if (accumulator > 0) outputBytes[outputLength] = (accumulated[0] << 2) | (accumulated[1] >> 4);
if (accumulator > 1) outputBytes[++outputLength] = (accumulated[1] << 4) | (accumulated[2] >> 2);
if (accumulator > 2) outputLength++;
//truncate data to match actual output length
outputData.length = outputLength;
return outputLength? outputData: nil;
}
- (NSString *)base64EncodedStringWithWrapWidth:(NSUInteger)wrapWidth
{
//ensure wrapWidth is a multiple of 4
wrapWidth = (wrapWidth / 4) * 4;
const char lookup[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
long long inputLength = [self length];
const unsigned char *inputBytes = [self bytes];
long long maxOutputLength = (inputLength / 3 + 1) * 4;
maxOutputLength += wrapWidth? (maxOutputLength / wrapWidth) * 2: 0;
unsigned char *outputBytes = (unsigned char *)malloc(maxOutputLength);
long long i;
long long outputLength = 0;
for (i = 0; i < inputLength - 2; i += 3)
{
outputBytes[outputLength++] = lookup[(inputBytes[i] & 0xFC) >> 2];
outputBytes[outputLength++] = lookup[((inputBytes[i] & 0x03) << 4) | ((inputBytes[i + 1] & 0xF0) >> 4)];
outputBytes[outputLength++] = lookup[((inputBytes[i + 1] & 0x0F) << 2) | ((inputBytes[i + 2] & 0xC0) >> 6)];
outputBytes[outputLength++] = lookup[inputBytes[i + 2] & 0x3F];
//add line break
if (wrapWidth && (outputLength + 2) % (wrapWidth + 2) == 0)
{
outputBytes[outputLength++] = '\r';
outputBytes[outputLength++] = '\n';
}
}
//handle left-over data
if (i == inputLength - 2)
{
// = terminator
outputBytes[outputLength++] = lookup[(inputBytes[i] & 0xFC) >> 2];
outputBytes[outputLength++] = lookup[((inputBytes[i] & 0x03) << 4) | ((inputBytes[i + 1] & 0xF0) >> 4)];
outputBytes[outputLength++] = lookup[(inputBytes[i + 1] & 0x0F) << 2];
outputBytes[outputLength++] = '=';
}
else if (i == inputLength - 1)
{
// == terminator
outputBytes[outputLength++] = lookup[(inputBytes[i] & 0xFC) >> 2];
outputBytes[outputLength++] = lookup[(inputBytes[i] & 0x03) << 4];
outputBytes[outputLength++] = '=';
outputBytes[outputLength++] = '=';
}
if (outputLength >= 4)
{
//truncate data to match actual output length
outputBytes = realloc(outputBytes, outputLength);
return [[NSString alloc] initWithBytesNoCopy:outputBytes
length:outputLength
encoding:NSASCIIStringEncoding
freeWhenDone:YES];
}
else if (outputBytes)
{
free(outputBytes);
}
return nil;
}
- (NSString *)base64EncodedString
{
return [self base64EncodedStringWithWrapWidth:0];
}
@end
@implementation NSString (Base64)
+ (NSString *)stringWithBase64EncodedString:(NSString *)string
{
NSData *data = [NSData dataWithBase64EncodedString:string];
if (data)
{
return [[self alloc] initWithData:data encoding:NSUTF8StringEncoding];
}
return nil;
}
- (NSString *)base64EncodedStringWithWrapWidth:(NSUInteger)wrapWidth
{
NSData *data = [self dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
return [data base64EncodedStringWithWrapWidth:wrapWidth];
}
- (NSString *)base64EncodedString
{
NSData *data = [self dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
return [data base64EncodedString];
}
- (NSString *)base64DecodedString
{
return [NSString stringWithBase64EncodedString:self];
}
- (NSData *)base64DecodedData
{
return [NSData dataWithBase64EncodedString:self];
}
@end |
Comment exploiter la base64?
Répondre avec citation
Partager