1
2 /* #include "config.h" */
3
4
5 #include <stdio.h>
6 #include <stdlib.h>
7
main(int argv,char * argc[])8 int main(int argv, char * argc[])
9 {
10 int xor_base = -1;
11
12 FILE * inf;
13 FILE * ouf;
14 char a, b;
15 int i, j;
16 char outfile[1024];
17 int inbracket = 0, quoted = 0;
18 unsigned long count;
19
20
21 /* char command[1024]; */
22
23 if ( argv < 3)
24 {
25 fprintf(stderr,"\nUsage: encode <XOR_VAL> "\
26 "<file>\n\n");
27 fprintf(stderr," This program will:\n");
28 fprintf(stderr," - take as input a source code file <file>,\n");
29 fprintf(stderr," - search for literal strings inclosed by _(), "\
30 "like '_(string)',\n");
31 fprintf(stderr," - replace _(string) by "\
32 "_(string XOR <XOR_VAL>),\n");
33 fprintf(stderr,
34 " - and output the result to './x_<file>'.\n\n");
35 fprintf(stderr," _() is supposed to be defined as a macro in "\
36 "the code, that\n");
37 fprintf(stderr," will allow the program to decode the xor'ed string "\
38 "at runtime.\n");
39 fprintf(stderr," The effect is that the compiled executable does "\
40 "not contain literal\n");
41 fprintf(stderr," strings that may trivially be found with the Unix "\
42 "'strings' command,\n");
43 fprintf(stderr," and thus reveal the nature of "\
44 "the program.\n");
45
46 return -1;
47 }
48
49 --argv; ++argc;
50
51 xor_base = atoi(argc[0]);
52
53 if (xor_base < 0 || (xor_base > 0 && xor_base < 128) || xor_base > 255)
54 {
55 fprintf(stderr, "\nERROR: encode: XOR_VAL=%d is out of "\
56 "range (0, 128..255)\n",
57 xor_base);
58 fprintf(stderr, "** please follow these steps to fix the problem:\n\n");
59 fprintf(stderr, " make clean\n");
60 fprintf(stderr, " ./configure [more options] "\
61 "--with-stealth=XOR_VAL (range 0, 128..255)\n");
62 fprintf(stderr, " make\n\n");
63 return -1;
64 }
65
66 /* fprintf(stderr, "<XOR_CODE> %d\n", xor_base); */
67
68 --argv; ++argc;
69
70 /* fprintf(stderr, "File: %d\n", argv); */
71
72 while (argv > 0)
73 {
74 inf = fopen(argc[0], "r");
75 if (inf == NULL)
76 {
77 fprintf(stderr, "Error opening %s\n", argc[0]);
78 return -1;
79 }
80 /* outfile name
81 */
82 i = 0; j = 0;
83 while (argc[0][i] != '\0')
84 {
85 if (argc[0][i] == '/') j = i+1;
86 ++i;
87 }
88 i = 0;
89 outfile[0] = 'x';
90 outfile[1] = '_';
91 outfile[2] = '\0';
92 while (argc[0][j+i] != '\0')
93 {
94 outfile[i+2] = argc[0][j+i];
95 ++i;
96 }
97 outfile[i+2] = '\0';
98 ouf = fopen(outfile, "w");
99 if (ouf == NULL)
100 {
101 fprintf(stderr, "Error opening %s\n", outfile);
102 return -1;
103 }
104
105 /* fprintf(stderr, "File: %s\n", argc[0]); */
106 count = 0;
107
108 while (fread(&a, 1, 1, inf) != 0)
109 {
110 count++;
111
112 if (a == '"' && quoted == 0)
113 {
114 quoted = 1;
115 fwrite(&a, 1, 1, ouf);
116 continue;
117 }
118
119 if (a == '"' && quoted == 1)
120 {
121 quoted = 0;
122 fwrite(&a, 1, 1, ouf);
123 continue;
124 }
125
126 if (a == '\n' && quoted == 1)
127 {
128 quoted = 0;
129 fwrite(&a, 1, 1, ouf);
130 continue;
131 }
132
133 /* macro start ?
134 */
135 if (a == '_' && inbracket == 0 && quoted == 0)
136 {
137 fwrite(&a, 1, 1, ouf);
138 b = '\0';
139 fread(&b, 1, 1, inf);
140 count++;
141 fwrite(&b, 1, 1, ouf);
142 if (b == '(') inbracket = 1;
143 continue;
144 }
145
146 /* macro end
147 */
148 if (a == ')' && quoted == 0 && inbracket == 1)
149 {
150 inbracket = 0;
151 /* fprintf(stdout, "\n"); */
152 fwrite(&a, 1, 1, ouf);
153 continue;
154 }
155
156 /* in a bracket
157 */
158 if (inbracket == 1 && quoted == 1)
159 {
160 /* fprintf(stdout, "%c", a); */
161 if (a == '\\')
162 {
163 fread(&b, 1, 1, inf);
164
165 /* escape sequences
166 */
167 if (b == 't' || b == 'n' || b == 'r' || b == '"')
168 {
169 fwrite(&a, 1, 1, ouf);
170 fwrite(&b, 1, 1, ouf);
171 }
172
173 else
174 {
175 a ^= (char) xor_base;
176 b ^= (char) xor_base;
177 }
178 }
179 else
180 {
181 a ^= (char) xor_base;
182 fwrite(&a, 1, 1, ouf);
183 }
184 continue;
185 }
186
187 fwrite(&a, 1, 1, ouf);
188 }
189
190 /* fprintf(stderr, "Bytes read: %ld\n", count); */
191 /* sprintf(command, "mv tempfile %s", argc[0]); */
192 /* system(command); */
193
194 fclose(ouf);
195 fclose(inf);
196 --argv; ++argc;
197 }
198 return 0;
199 }
200
201