搜狐公司的测评
2011-09-12 10:54 Firefly727 阅读(366) 评论(0) 编辑 收藏 举报搜狐公司的测评题目(C/C++) [Dev-C++]
1 #include <stdio.h>
2 #include <stdlib.h>
3 //#include <stdint.h>
4 #include <assert.h>
5 #include <string.h>
6
7 typedef unsigned int uint32_t;
8 typedef unsigned char uint8_t;
9
10 /*******************************************************************************
11 * 搜狐评测题，通过加密和解密两个步骤
12 ******************************************************************************/
13
14 int encode(constvoid* raw_in, void* raw_out, uint32_t password, size_t len)
15 {
16 const uint8_t*in= (const uint8_t*)raw_in;
17 uint8_t*out= (uint8_t*)raw_out;
18 // 对于 a = b ^ c 来说； 可以 b = a ^ c = b ^ c ^ c; 即对于下面中
19 // 的所有 ^ 都只要重新来一次 ^ 就OK了
20 uint32_t seed = password ^0xa4b9cdddu;
21 for (size_t i =0 ; i < len; ++i) {
22 // 输入首先右移一位; 存放在a中，即输入的高7位存放在a的低7位
23 // a = zxxx xxxx
24 uint8_t a = ( in[i] ^ seed ) >>1;
25 // 下面这句是将输入左移 19，然后右移12位，相当于左移了7位
26 // 即输入的低1位存在b的最高位 b = xzzz zzzz
27 uint8_t b = ( ( ((uint32_t)in[i]) <<19 ) ^ seed ) >> (19-7);
28 // 127 = 0111 1111 即将a的第7位置为0； a = 0\xxx xxxx(原来in的高7位)
29 a &=127;
30 // 128 = 1000 0000 即将b的第6~0位置为0 b = x(原来in的低1位)/000 0000
31 b &=128;
32 // 下面这句没有用，因为b右移三位，直接变成了0； 再与a异或的话就直接是a原来的值了
33 a =127& ( a ^ (b <<3));
34 // 最后out[i] 存放的就是将in[i]对调了 ;
35 out[i] = a | b;
36 // 种子的话，加密和解密的是一样的，只是这里的out[i]改为in[i]就OK了，因为加密
37 // 算法中的输出就是解密算法时的输入; 而初始种子都是一样的
38 seed = (((seed <<7) ^ seed ^out[i]) +144123481);
39 }
40 }
41
42
43 int decode(constvoid* raw_in, void* raw_out, uint32_t password, size_t len)
44 {
45 const uint8_t*in= (const uint8_t*)raw_in;
46 uint8_t*out= (uint8_t*)raw_out;
47 //
48 uint32_t seed = password ^0xa4b9cdddu;
49 for (size_t i =0 ; i < len; ++i) {
50 // 将经过加密的输入in[i]的低7位放在a高7位
51 uint8_t a = ( in[i] <<1 ) ^ seed;
52 // 将经过加密的输入in[i]的高1位放在b的低1位
53 uint8_t b = (((uint32_t)in[i] << (19-7))^seed) >>19;
54 // 254 = 1111 1110 将a的最后1位强制清零;注意加密中存放在a中是低7位，所以与127与；而这里是存在a的高七位，所以是254
55 a &=254;
56 // 将b高7位强制清零
57 b &=1;
58 // 两者异或就得到了加密前的数据了
59 out[i] = a|b;
60 // 种子解释看加密
61 seed = (((seed <<7) ^ seed ^in[i]) +144123481);
62 }
63 }
64 int main()
65 {
66 const uint8_t buf1[] = {0xbe, 0x58, 0xd5, 0xcb, 0xc7, 0x85, 0x84, 0x3a, 0xa2, 0x30, 0xa3, 0x36, 0x5f, 0x43, 0xc9, 0x53, 0x67, 0xf3, 0xac, 0xed, 0xc4, 0x38, 0xb7, 0xdf, 0xec, 0x51, 0x09, 0xbf, 0x2a, 0x32, 0x6b, 0x42, 0x32, 0x71, 0xe0, 0x93, 0x8b, 0xeb, 0x1c, 0xd2, 0x62, 0x6a, 0xb6, 0x10, 0x09, 0x89, 0xb6, 0xb1, 0x29, 0x31, 0xd2, 0xb9, 0xa0, 0xb5, 0x5d, 0x40, 0xf8, 0x74, 0xc3, 0x35, 0x70, 0x95, 0x2a, 0x0b, 0x5a, 0x82, 0x51, 0x05, };
67 uint8_t buf2[100] = {};
68 const uint32_t password =0x1c1c2c6bu;
69 const size_t len =sizeof(buf1);
70 decode(buf1, buf2, password, len);
71 printf("%s\n", buf2);
72 system("PAUSE");
73 return EXIT_SUCCESS;
74 }
输出结果:
1 #include <stdio.h>
2 #include <stdlib.h>
3 //#include <stdint.h>
4 #include <assert.h>
5 #include <string.h>
6 typedef unsigned int uint32_t;
7 typedef unsigned char uint8_t;
8
9 int encode(constvoid* raw_in, void* raw_out, uint32_t password, size_t len)
10 {
11 const uint8_t*in= (const uint8_t*)raw_in;
12 uint8_t*out= (uint8_t*)raw_out;
13
14 uint32_t seed = password ^0x91e69948u;
15 for (size_t i =0 ; i < len; ++i) {
16
17 uint8_t a = ( in[i] ^ seed ) >>5;
18
19 uint8_t b = ( ( ((uint32_t)in[i]) <<19 ) ^ seed ) >> (19-3);
20 a &=7;
21 b &=248;
22 a =7& ( a ^ (b <<3));
23 out[i] = a | b;
24 seed = ((seed ^in[i]) *536513+in[i]);
25 }
26 return0;
27 }
28
29
30 int decode(constvoid* raw_in, void* raw_out, uint32_t password, size_t len)
31 {
32 const uint8_t*in= (const uint8_t*)raw_in;
33 uint8_t*out= (uint8_t*)raw_out;
34
35 uint32_t seed = password ^0x91e69948u;
36 for (size_t i =0 ; i < len; ++i) {
37 uint8_t a = (in[i] <<5) ^ seed;
38 uint8_t b = ( ((uint32_t)in[i] << (19-3)) ^seed ) >>19;
39 a &=224;
40 b &=31;
41 out[i] = a | b;
42 seed = ((seed ^out[i]) *536513+out[i]);
43 }
44 return0;
45 }
46 int main()
47 {
48 const uint8_t buf1[] = {0xfe, 0x7c, 0x75, 0xf8, 0x85, 0x14, 0x1b, 0x21, 0xee, 0x13, 0x52, 0xb6, 0xc8, 0xfd, 0x06, 0x40, 0x92, 0x7c, };
49 uint8_t buf2[100] = {};
50 const uint32_t password =0x27430952u;
51 const size_t len =sizeof(buf1);
52 decode(buf1, buf2, password, len);
53 printf("%s\n", buf2);
54 system("PAUSE");
55 return0;
56 }
输出结果
