FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavutil/tea.c
Date: 2024-04-18 20:30:25
Exec Total Coverage
Lines: 49 49 100.0%
Functions: 4 4 100.0%
Branches: 20 20 100.0%
Line Branch Exec Source
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>
26 #include "intreadwrite.h"
27 #include "mem.h"
28 #include "tea.h"
29
30 typedef struct AVTEA {
31 uint32_t key[16];
32 int rounds;
33 } AVTEA;
34
35 2 struct AVTEA *av_tea_alloc(void)
36 {
37 2 return av_mallocz(sizeof(struct AVTEA));
38 }
39
40 const int av_tea_size = sizeof(AVTEA);
41
42 6 void av_tea_init(AVTEA *ctx, const uint8_t key[16], int rounds)
43 {
44 int i;
45
46
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 30 for (i = 0; i < 4; i++)
47 24 ctx->key[i] = AV_RB32(key + (i << 2));
48
49 6 ctx->rounds = rounds;
50 6 }
51
52 713 static void tea_crypt_ecb(AVTEA *ctx, uint8_t *dst, const uint8_t *src,
53 int decrypt, uint8_t *iv)
54 {
55 uint32_t v0, v1;
56 713 int rounds = ctx->rounds;
57 uint32_t k0, k1, k2, k3;
58 713 k0 = ctx->key[0];
59 713 k1 = ctx->key[1];
60 713 k2 = ctx->key[2];
61 713 k3 = ctx->key[3];
62
63 713 v0 = AV_RB32(src);
64 713 v1 = AV_RB32(src + 4);
65
66
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 713 if (decrypt) {
67 int i;
68 690 uint32_t delta = 0x9E3779B9U, sum = delta * (rounds / 2);
69
70
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 7074 for (i = 0; i < rounds / 2; i++) {
71 6384 v1 -= ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3);
72 6384 v0 -= ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
73 6384 sum -= delta;
74 }
75
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 690 if (iv) {
76 32 v0 ^= AV_RB32(iv);
77 32 v1 ^= AV_RB32(iv + 4);
78 32 memcpy(iv, src, 8);
79 }
80 } else {
81 int i;
82 23 uint32_t sum = 0, delta = 0x9E3779B9U;
83
84
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 687 for (i = 0; i < rounds / 2; i++) {
85 664 sum += delta;
86 664 v0 += ((v1 << 4) + k0) ^ (v1 + sum) ^ ((v1 >> 5) + k1);
87 664 v1 += ((v0 << 4) + k2) ^ (v0 + sum) ^ ((v0 >> 5) + k3);
88 }
89 }
90
91 713 AV_WB32(dst, v0);
92 713 AV_WB32(dst + 4, v1);
93 713 }
94
95 27 void av_tea_crypt(AVTEA *ctx, uint8_t *dst, const uint8_t *src, int count,
96 uint8_t *iv, int decrypt)
97 {
98 int i;
99
100
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 27 if (decrypt) {
101
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 708 while (count--) {
102 690 tea_crypt_ecb(ctx, dst, src, decrypt, iv);
103
104 690 src += 8;
105 690 dst += 8;
106 }
107 } else {
108
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 32 while (count--) {
109
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 23 if (iv) {
110
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 144 for (i = 0; i < 8; i++)
111 128 dst[i] = src[i] ^ iv[i];
112 16 tea_crypt_ecb(ctx, dst, dst, decrypt, NULL);
113 16 memcpy(iv, dst, 8);
114 } else {
115 7 tea_crypt_ecb(ctx, dst, src, decrypt, NULL);
116 }
117 23 src += 8;
118 23 dst += 8;
119 }
120 }
121 27 }
122