Line data Source code
1 : /*
2 : Mosh: the mobile shell
3 : Copyright 2012 Keith Winstein
4 :
5 : This program is free software: you can redistribute it and/or modify
6 : it under the terms of the GNU General Public License as published by
7 : the Free Software Foundation, either version 3 of the License, or
8 : (at your option) any later version.
9 :
10 : This program is distributed in the hope that it will be useful,
11 : but WITHOUT ANY WARRANTY; without even the implied warranty of
12 : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 : GNU General Public License for more details.
14 :
15 : You should have received a copy of the GNU General Public License
16 : along with this program. If not, see <http://www.gnu.org/licenses/>.
17 :
18 : In addition, as a special exception, the copyright holders give
19 : permission to link the code of portions of this program with the
20 : OpenSSL library under certain conditions as described in each
21 : individual source file, and distribute linked combinations including
22 : the two.
23 :
24 : You must obey the GNU General Public License in all respects for all
25 : of the code used other than OpenSSL. If you modify file(s) with this
26 : exception, you may extend this exception to your version of the
27 : file(s), but you are not obligated to do so. If you do not wish to do
28 : so, delete this exception statement from your version. If you delete
29 : this exception statement from all source files in the program, then
30 : also delete it here.
31 : */
32 :
33 : #include <string.h>
34 : #include <stdlib.h>
35 :
36 : #include "fatal_assert.h"
37 : #include "base64.h"
38 :
39 : static const char table[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
40 :
41 : static const unsigned char reverse[] = {
42 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
43 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
44 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f,
45 : 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
46 : 0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
47 : 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff,
48 : 0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
49 : 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff,
50 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
51 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
52 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
53 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
54 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
55 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
56 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
57 : 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
58 : };
59 :
60 : /* Reverse maps from an ASCII char to a base64 sixbit value. Returns > 0x3f on failure. */
61 5788730 : static unsigned char base64_char_to_sixbit(unsigned char c)
62 : {
63 5788730 : return reverse[c];
64 : }
65 :
66 263130 : bool base64_decode( const char *b64, const size_t b64_len,
67 : uint8_t *raw, size_t *raw_len )
68 : {
69 263130 : fatal_assert( b64_len == 24 ); /* only useful for Mosh keys */
70 263130 : fatal_assert( *raw_len == 16 );
71 :
72 : uint32_t bytes = 0;
73 6051846 : for (int i = 0; i < 22; i++) {
74 5788730 : unsigned char sixbit = base64_char_to_sixbit(*(b64++));
75 5788730 : if (sixbit > 0x3f) {
76 : return false;
77 : }
78 5788716 : bytes <<= 6;
79 5788716 : bytes |= sixbit;
80 : /* write groups of 3 */
81 5788716 : if (i % 4 == 3) {
82 1315618 : raw[0] = bytes >> 16;
83 1315618 : raw[1] = bytes >> 8;
84 1315618 : raw[2] = bytes;
85 1315618 : raw += 3;
86 1315618 : bytes = 0;
87 : }
88 : }
89 : /* last byte of output */
90 263116 : *raw = bytes >> 4;
91 263116 : if (b64[0] != '=' || b64[1] != '=') {
92 12 : return false;
93 : }
94 : return true;
95 : }
96 :
97 1049988 : void base64_encode( const uint8_t *raw, const size_t raw_len,
98 : char *b64, const size_t b64_len )
99 : {
100 1049988 : fatal_assert( b64_len == 24 ); /* only useful for Mosh keys */
101 1049988 : fatal_assert( raw_len == 16 );
102 :
103 : /* first 15 bytes of input */
104 6299928 : for (int i = 0; i < 5; i++) {
105 5249940 : uint32_t bytes = (raw[0] << 16) | (raw[1] << 8) | raw[2];
106 5249940 : b64[0] = table[(bytes >> 18) & 0x3f];
107 5249940 : b64[1] = table[(bytes >> 12) & 0x3f];
108 5249940 : b64[2] = table[(bytes >> 6) & 0x3f];
109 5249940 : b64[3] = table[(bytes) & 0x3f];
110 5249940 : raw += 3;
111 5249940 : b64 += 4;
112 : }
113 :
114 : /* last byte of input, last 4 of output */
115 1049988 : uint8_t lastchar = *raw;
116 1049988 : b64[0] = table[(lastchar >> 2) & 0x3f];
117 1049988 : b64[1] = table[(lastchar << 4) & 0x3f];
118 1049988 : b64[2] = '=';
119 1049988 : b64[3] = '=';
120 1049988 : }
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