C語言寫的一個簡單文件加密程序

C語言寫的一個簡單文件加密程序：

1. #include<stdio.h>
2. #include<stdlib.h>
3. #include<string.h>
5. int decrypt(FILE *in,FILE *out);
6. int encrypt(FILE *in,FILE *out);
7. unsigned char atoh(char *hexstr);
9. int main(int argc,char **argv)
10. {
11. if(argc > 1 && strcmp(argv[1],"--help") == 0)
12. {
13. printf("\nusage: linkrules_god [-e|-d] inputfile outputfile\n");
14. printf(" -e encrypt inputfile to outputfile.\n");
15. printf(" -d decrypt inputfile to outputfile.\n\n");
16. exit(0);
17. }
18. if(argc != 4)
19. {
20. fprintf(stderr,"%s\n","please using --help go get help.");
21. exit(-1);
22. }
25. FILE *in = fopen(argv[2],"rb");
26. FILE *out = fopen(argv[3],"w");
27. if(in == NULL || out == NULL)
28. {
29. fprintf(stderr,"%s\n","open file error!");
30. exit(1);
31. }
33. if(argv[1][1] == 'e')
34. {
35. encrypt(in,out);
36. }
37. else if(argv[1][1] == 'd')
38. {
39. decrypt(in,out);
40. }
42. fclose(in);
43. fclose(out);
44. return 0;
45. }
47. int encrypt(FILE *in,FILE *out)
48. {
49. if(in == NULL || out == NULL)
50. {
51. fprintf(stderr,"%s\n","file error!\n");
52. return -1;
53. }
55. unsigned char hex;
56. while(fread(&hex,1,1,in))
57. {
58. hex = ~hex^0x92;
59. fprintf(out,"%02X",hex);
60. }
61. return 0;
62. }
66. int decrypt(FILE *in,FILE *out)
67. {
68. if(in == NULL || out == NULL)
69. {
70. fprintf(stderr,"%s\n","file error!");
71. return -1;
72. }
74. unsigned char hexstr[3];
75. unsigned char hex = 0;
76. int i = 0;
77. while(fread(&hexstr,2,1,in))
78. {
79. hex = atoh(hexstr);
80. hex = ~(hex ^ 0x92);
81. fwrite(&hex,1,1,out);
82. }
84. return 0;
85. }
88. /* convert string to hex */
89. unsigned char atoh(char *hexstr)
90. {
91. int hextodec[]={0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
92. char chtodec[] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
93. unsigned char hexnum = 0;
94. for(int i = 0; i < sizeof(chtodec); ++i)
95. {
96. if(hexstr[0] == chtodec[i])
97. {
98. hexnum += hextodec[i]*16;
99. }
100. }
102. for(int i = 0; i < sizeof(chtodec); ++i)
103. {
104. if(hexstr[1] == chtodec[i])
105. {
106. hexnum += hextodec[i];
107. }
108. }
110. return hexnum;
111. }

encrypt -e sourcefile outputfile 加密

encrypt -d sourcefile outputfile 解密

encrypt --help 幫助

輸出的加密文件中的內容：