1 /*
2 * A 32-bit implementation of the TEA algorithm
3 * Copyright (c) 2015 Vesselin Bontchev
4 *
5 * Loosely based on the implementation of David Wheeler and Roger Needham,
6 * https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm#Reference_code
7 *
8 * This file is part of FFmpeg.
9 *
10 * FFmpeg is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU Lesser General Public
12 * License as published by the Free Software Foundation; either
13 * version 2.1 of the License, or (at your option) any later version.
14 *
15 * FFmpeg is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * Lesser General Public License for more details.
19 *
20 * You should have received a copy of the GNU Lesser General Public
21 * License along with FFmpeg; if not, write to the Free Software
22 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 */
24
25 #include <string.h>
29
34
36 {
38 }
39
41
43 {
45
46 for (
i = 0;
i < 4;
i++)
48
50 }
51
53 int decrypt, uint8_t *iv)
54 {
57 uint32_t k0, k1, k2, k3;
62
65
66 if (decrypt) {
69
71 v1 -= ((
v0 << 4) + k2) ^ (
v0 + sum) ^ ((
v0 >> 5) + k3);
72 v0 -= ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
74 }
75 if (iv) {
79 }
80 } else {
82 uint32_t sum = 0,
delta = 0x9E3779B9
U;
83
86 v0 += ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
87 v1 += ((
v0 << 4) + k2) ^ (
v0 + sum) ^ ((
v0 >> 5) + k3);
88 }
89 }
90
93 }
94
96 uint8_t *iv, int decrypt)
97 {
99
100 if (decrypt) {
101 while (count--) {
103
105 dst += 8;
106 }
107 } else {
108 while (count--) {
109 if (iv) {
110 for (
i = 0;
i < 8;
i++)
113 memcpy(iv, dst, 8);
114 } else {
116 }
118 dst += 8;
119 }
120 }
121 }