羊城杯202009re部分题解

原文地址:http://pluie.top/2020/09/14/羊城杯202009re部分题解/

login

pyinstaller 打包的exe文件,反编译为.py文件,具体做法可以参考我的另一篇文章。pyinstaller打包的exe文件反编译为.py文件
.py文件源码:

# uncompyle6 version 3.7.3
# Python bytecode 3.7 (3394)
# Decompiled from: Python 3.8.5 (tags/v3.8.5:580fbb0, Jul 20 2020, 15:57:54) [MSC v.1924 64 bit (AMD64)]
# Embedded file name: login.py
# Compiled at: 1995-09-28 00:18:56
# Size of source mod 2**32: 257 bytes
import sys
input1 = input('input something:')
if len(input1) != 14:
    print('Wrong length!')
    sys.exit()
else:
    code = []
    for i in range(13):
        code.append(ord(input1[i]) ^ ord(input1[(i + 1)]))

    code.append(ord(input1[13]))
    a1 = code[2]
    a2 = code[1]
    a3 = code[0]
    a4 = code[3]
    a5 = code[4]
    a6 = code[5]
    a7 = code[6]
    a8 = code[7]
    a9 = code[9]
    a10 = code[8]
    a11 = code[10]
    a12 = code[11]
    a13 = code[12]
    a14 = code[13]
    if (a1 * 88 + a2 * 67 + a3 * 65 - a4 * 5 + a5 * 43 + a6 * 89 + a7 * 25 + a8 * 13 - a9 * 36 + a10 * 15 + a11 * 11 + a12 * 47 - a13 * 60 + a14 * 29 == 22748) & (a1 * 89 + a2 * 7 + a3 * 12 - a4 * 25 + a5 * 41 + a6 * 23 + a7 * 20 - a8 * 66 + a9 * 31 + a10 * 8 + a11 * 2 - a12 * 41 - a13 * 39 + a14 * 17 == 7258) & (a1 * 28 + a2 * 35 + a3 * 16 - a4 * 65 + a5 * 53 + a6 * 39 + a7 * 27 + a8 * 15 - a9 * 33 + a10 * 13 + a11 * 101 + a12 * 90 - a13 * 34 + a14 * 23 == 26190) & (a1 * 23 + a2 * 34 + a3 * 35 - a4 * 59 + a5 * 49 + a6 * 81 + a7 * 25 + (a8 << 7) - a9 * 32 + a10 * 75 + a11 * 81 + a12 * 47 - a13 * 60 + a14 * 29 == 37136) & (a1 * 38 + a2 * 97 + a3 * 35 - a4 * 52 + a5 * 42 + a6 * 79 + a7 * 90 + a8 * 23 - a9 * 36 + a10 * 57 + a11 * 81 + a12 * 42 - a13 * 62 - a14 * 11 == 27915) & (a1 * 22 + a2 * 27 + a3 * 35 - a4 * 45 + a5 * 47 + a6 * 49 + a7 * 29 + a8 * 18 - a9 * 26 + a10 * 35 + a11 * 41 + a12 * 40 - a13 * 61 + a14 * 28 == 17298) & (a1 * 12 + a2 * 45 + a3 * 35 - a4 * 9 - a5 * 42 + a6 * 86 + a7 * 23 + a8 * 85 - a9 * 47 + a10 * 34 + a11 * 76 + a12 * 43 - a13 * 44 + a14 * 65 == 19875) & (a1 * 79 + a2 * 62 + a3 * 35 - a4 * 85 + a5 * 33 + a6 * 79 + a7 * 86 + a8 * 14 - a9 * 30 + a10 * 25 + a11 * 11 + a12 * 57 - a13 * 50 - a14 * 9 == 22784) & (a1 * 8 + a2 * 6 + a3 * 64 - a4 * 85 + a5 * 73 + a6 * 29 + a7 * 2 + a8 * 23 - a9 * 36 + a10 * 5 + a11 * 2 + a12 * 47 - a13 * 64 + a14 * 27 == 9710) & (a1 * 67 - a2 * 68 + a3 * 68 - a4 * 51 - a5 * 43 + a6 * 81 + a7 * 22 - a8 * 12 - a9 * 38 + a10 * 75 + a11 * 41 + a12 * 27 - a13 * 52 + a14 * 31 == 13376) & (a1 * 85 + a2 * 63 + a3 * 5 - a4 * 51 + a5 * 44 + a6 * 36 + a7 * 28 + a8 * 15 - a9 * 6 + a10 * 45 + a11 * 31 + a12 * 7 - a13 * 67 + a14 * 78 == 24065) & (a1 * 47 + a2 * 64 + a3 * 66 - a4 * 5 + a5 * 43 + a6 * 112 + a7 * 25 + a8 * 13 - a9 * 35 + a10 * 95 + a11 * 21 + a12 * 43 - a13 * 61 + a14 * 20 == 27687) & (a1 * 89 + a2 * 67 + a3 * 85 - a4 * 25 + a5 * 49 + a6 * 89 + a7 * 23 + a8 * 56 - a9 * 92 + a10 * 14 + a11 * 89 + a12 * 47 - a13 * 61 - a14 * 29 == 29250) & (a1 * 95 + a2 * 34 + a3 * 62 - a4 * 9 - a5 * 43 + a6 * 83 + a7 * 25 + a8 * 12 - a9 * 36 + a10 * 16 + a11 * 51 + a12 * 47 - a13 * 60 - a14 * 24 == 15317):
        print('flag is GWHT{md5(your_input)}')
        print('Congratulations and have fun!')
    else:
        print('Sorry,plz try again...')

写脚本时需要用到z3这个工具,可以参考Z3Py在CTF逆向中的运用


from z3 import *
import hashlib

a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14 = BitVecs('a1 a2 a3 a4 a5 a6 a7 a8 a9 a10 a11 a12 a13 a14', 7)

solve(a1 * 88 + a2 * 67 + a3 * 65 - a4 * 5 + a5 * 43 + a6 * 89 + a7 * 25 + a8 * 13 - a9 * 36 + a10 * 15 + a11 * 11 + a12 * 47 - a13 * 60 + a14 * 29 == 22748 , a1 * 89 + a2 * 7 + a3 * 12 - a4 * 25 + a5 * 41 + a6 * 23 + a7 * 20 - a8 * 66 + a9 * 31 + a10 * 8 + a11 * 2 - a12 * 41 - a13 * 39 + a14 * 17 == 7258 , a1 * 28 + a2 * 35 + a3 * 16 - a4 * 65 + a5 * 53 + a6 * 39 + a7 * 27 + a8 * 15 - a9 * 33 + a10 * 13 + a11 * 101 + a12 * 90 - a13 * 34 + a14 * 23 == 26190 , a1 * 23 + a2 * 34 + a3 * 35 - a4 * 59 + a5 * 49 + a6 * 81 + a7 * 25 + (a8 << 7) - a9 * 32 + a10 * 75 + a11 * 81 + a12 * 47 - a13 * 60 + a14 * 29 == 37136 , a1 * 38 + a2 * 97 + a3 * 35 - a4 * 52 + a5 * 42 + a6 * 79 + a7 * 90 + a8 * 23 - a9 * 36 + a10 * 57 + a11 * 81 + a12 * 42 - a13 * 62 - a14 * 11 == 27915 , a1 * 22 + a2 * 27 + a3 * 35 - a4 * 45 + a5 * 47 + a6 * 49 + a7 * 29 + a8 * 18 - a9 * 26 + a10 * 35 + a11 * 41 + a12 * 40 - a13 * 61 + a14 * 28 == 17298 , a1 * 12 + a2 * 45 + a3 * 35 - a4 * 9 - a5 * 42 + a6 * 86 + a7 * 23 + a8 * 85 - a9 * 47 + a10 * 34 + a11 * 76 + a12 * 43 - a13 * 44 + a14 * 65 == 19875 , a1 * 79 + a2 * 62 + a3 * 35 - a4 * 85 + a5 * 33 + a6 * 79 + a7 * 86 + a8 * 14 - a9 * 30 + a10 * 25 + a11 * 11 + a12 * 57 - a13 * 50 - a14 * 9 == 22784 , a1 * 8 + a2 * 6 + a3 * 64 - a4 * 85 + a5 * 73 + a6 * 29 + a7 * 2 + a8 * 23 - a9 * 36 + a10 * 5 + a11 * 2 + a12 * 47 - a13 * 64 + a14 * 27 == 9710 , a1 * 67 - a2 * 68 + a3 * 68 - a4 * 51 - a5 * 43 + a6 * 81 + a7 * 22 - a8 * 12 - a9 * 38 + a10 * 75 + a11 * 41 + a12 * 27 - a13 * 52 + a14 * 31 == 13376 , a1 * 85 + a2 * 63 + a3 * 5 - a4 * 51 + a5 * 44 + a6 * 36 + a7 * 28 + a8 * 15 - a9 * 6 + a10 * 45 + a11 * 31 + a12 * 7 - a13 * 67 + a14 * 78 == 24065 , a1 * 47 + a2 * 64 + a3 * 66 - a4 * 5 + a5 * 43 + a6 * 112 + a7 * 25 + a8 * 13 - a9 * 35 + a10 * 95 + a11 * 21 + a12 * 43 - a13 * 61 + a14 * 20 == 27687 , a1 * 89 + a2 * 67 + a3 * 85 - a4 * 25 + a5 * 49 + a6 * 89 + a7 * 23 + a8 * 56 - a9 * 92 + a10 * 14 + a11 * 89 + a12 * 47 - a13 * 61 - a14 * 29 == 29250 , a1 * 95 + a2 * 34 + a3 * 62 - a4 * 9 - a5 * 43 + a6 * 83 + a7 * 25 + a8 * 12 - a9 * 36 + a10 * 16 + a11 * 51 + a12 * 47 - a13 * 60 - a14 * 24 == 15317)

A = [10,24,119,7,104,43,28,91,108,52,88,74,88,33]
i = 12
while i >= 0:
    A[i] ^= A[i+1]
    i -= 1

for i in A:
    print(chr(i), end = '')
a = b'U_G07_th3_k3y!'
print(hashlib.md5(a).hexdigest())

需要注意的是,约束条件存在位移操作,所以不能用Int方法创建未知量,而是用BitVecs方法,添加约束条件用solve方法

附件下载 提取码:k4n4

Bytecode

python字节码反汇编生成的伪代码,

  4           0 LOAD_CONST               0 (3)
              3 LOAD_CONST               1 (37)
              6 LOAD_CONST               2 (72)
              9 LOAD_CONST               3 (9)
             12 LOAD_CONST               4 (6)
             15 LOAD_CONST               5 (132)
             18 BUILD_LIST               6
             21 STORE_NAME               0 (en)

  5          24 LOAD_CONST               6 (101)
             27 LOAD_CONST               7 (96)
             30 LOAD_CONST               8 (23)
             33 LOAD_CONST               9 (68)
             36 LOAD_CONST              10 (112)
             39 LOAD_CONST              11 (42)
             42 LOAD_CONST              12 (107)
             45 LOAD_CONST              13 (62)
             48 LOAD_CONST               7 (96)
             51 LOAD_CONST              14 (53)
             54 LOAD_CONST              15 (176)
             57 LOAD_CONST              16 (179)
             60 LOAD_CONST              17 (98)
             63 LOAD_CONST              14 (53)
             66 LOAD_CONST              18 (67)
             69 LOAD_CONST              19 (29)
             72 LOAD_CONST              20 (41)
             75 LOAD_CONST              21 (120)
             78 LOAD_CONST              22 (60)
             81 LOAD_CONST              23 (106)
             84 LOAD_CONST              24 (51)
             87 LOAD_CONST               6 (101)
             90 LOAD_CONST              25 (178)
             93 LOAD_CONST              26 (189)
             96 LOAD_CONST               6 (101)
             99 LOAD_CONST              27 (48)
            102 BUILD_LIST              26
            105 STORE_NAME               1 (output)

  7         108 LOAD_CONST              28 ('welcome to GWHT2020')
            111 PRINT_ITEM          
            112 PRINT_NEWLINE       

  9         113 LOAD_NAME                2 (raw_input)
            116 LOAD_CONST              29 ('please input your flag:')
            119 CALL_FUNCTION            1
            122 STORE_NAME               3 (flag)

 10         125 LOAD_NAME                3 (flag)
            128 STORE_NAME               4 (str)

 12         131 LOAD_NAME                5 (len)
            134 LOAD_NAME                4 (str)
            137 CALL_FUNCTION            1
            140 STORE_NAME               6 (a)

 13         143 LOAD_NAME                6 (a)
            146 LOAD_CONST              30 (38)
            149 COMPARE_OP               0 (<)
            152 POP_JUMP_IF_FALSE      173

 14         155 LOAD_CONST              31 ('lenth wrong!')
            158 PRINT_ITEM          
            159 PRINT_NEWLINE       

 15         160 LOAD_NAME                7 (exit)
            163 LOAD_CONST              32 (0)
            166 CALL_FUNCTION            1
            169 POP_TOP             
            170 JUMP_FORWARD             0 (to 173)

 17     >>  173 LOAD_NAME                8 (ord)
            176 LOAD_NAME                4 (str)
            179 LOAD_CONST              32 (0)
            182 BINARY_SUBSCR       
            183 CALL_FUNCTION            1
            186 LOAD_CONST              33 (2020)
            189 BINARY_MULTIPLY     
            190 LOAD_NAME                8 (ord)
            193 LOAD_NAME                4 (str)
            196 LOAD_CONST              34 (1)
            199 BINARY_SUBSCR       
            200 CALL_FUNCTION            1
            203 BINARY_ADD          
            204 LOAD_CONST              33 (2020)
            207 BINARY_MULTIPLY     
            208 LOAD_NAME                8 (ord)
            211 LOAD_NAME                4 (str)
            214 LOAD_CONST              35 (2)
            217 BINARY_SUBSCR       
            218 CALL_FUNCTION            1
            221 BINARY_ADD          
            222 LOAD_CONST              33 (2020)
            225 BINARY_MULTIPLY     
            226 LOAD_NAME                8 (ord)
            229 LOAD_NAME                4 (str)
            232 LOAD_CONST               0 (3)
            235 BINARY_SUBSCR       
            236 CALL_FUNCTION            1
            239 BINARY_ADD          
            240 LOAD_CONST              33 (2020)
            243 BINARY_MULTIPLY     
            244 LOAD_NAME                8 (ord)
            247 LOAD_NAME                4 (str)
            250 LOAD_CONST              36 (4)
            253 BINARY_SUBSCR       
            254 CALL_FUNCTION            1
            257 BINARY_ADD          
            258 LOAD_CONST              37 (1182843538814603)
            261 COMPARE_OP               2 (==)
            264 POP_JUMP_IF_FALSE      275

 18         267 LOAD_CONST              38 ('good!continuexe2x80xa6xe2x80xa6')
            270 PRINT_ITEM          
            271 PRINT_NEWLINE       
            272 JUMP_FORWARD            15 (to 290)

 20     >>  275 LOAD_CONST              39 ('bye~')
            278 PRINT_ITEM          
            279 PRINT_NEWLINE       

 21         280 LOAD_NAME                7 (exit)
            283 LOAD_CONST              32 (0)
            286 CALL_FUNCTION            1
            289 POP_TOP             

 23     >>  290 BUILD_LIST               0
            293 STORE_NAME               9 (x)

 24         296 LOAD_CONST              40 (5)
            299 STORE_NAME              10 (k)

 25         302 SETUP_LOOP             128 (to 433)
            305 LOAD_NAME               11 (range)
            308 LOAD_CONST              41 (13)
            311 CALL_FUNCTION            1
            314 GET_ITER            
        >>  315 FOR_ITER               114 (to 432)
            318 STORE_NAME              12 (i)

 26         321 LOAD_NAME                8 (ord)
            324 LOAD_NAME                4 (str)
            327 LOAD_NAME               10 (k)
            330 BINARY_SUBSCR       
            331 CALL_FUNCTION            1
            334 STORE_NAME              13 (b)

 27         337 LOAD_NAME                8 (ord)
            340 LOAD_NAME                4 (str)
            343 LOAD_NAME               10 (k)
            346 LOAD_CONST              34 (1)
            349 BINARY_ADD          
            350 BINARY_SUBSCR       
            351 CALL_FUNCTION            1
            354 STORE_NAME              14 (c)

 28         357 LOAD_NAME               14 (c)
            360 LOAD_NAME                0 (en)
            363 LOAD_NAME               12 (i)
            366 LOAD_CONST               4 (6)
            369 BINARY_MODULO       
            370 BINARY_SUBSCR       
            371 BINARY_XOR          
            372 STORE_NAME              15 (a11)

 29         375 LOAD_NAME               13 (b)
            378 LOAD_NAME                0 (en)
            381 LOAD_NAME               12 (i)
            384 LOAD_CONST               4 (6)
            387 BINARY_MODULO       
            388 BINARY_SUBSCR       
            389 BINARY_XOR          
            390 STORE_NAME              16 (a22)

 30         393 LOAD_NAME                9 (x)
            396 LOAD_ATTR               17 (append)
            399 LOAD_NAME               15 (a11)
            402 CALL_FUNCTION            1
            405 POP_TOP             

 31         406 LOAD_NAME                9 (x)
            409 LOAD_ATTR               17 (append)
            412 LOAD_NAME               16 (a22)
            415 CALL_FUNCTION            1
            418 POP_TOP             

 32         419 LOAD_NAME               10 (k)
            422 LOAD_CONST              35 (2)
            425 INPLACE_ADD         
            426 STORE_NAME              10 (k)
            429 JUMP_ABSOLUTE          315
        >>  432 POP_BLOCK           

 33     >>  433 LOAD_NAME                9 (x)
            436 LOAD_NAME                1 (output)
            439 COMPARE_OP               2 (==)
            442 POP_JUMP_IF_FALSE      453

 34         445 LOAD_CONST              38 ('good!continuexe2x80xa6xe2x80xa6')
            448 PRINT_ITEM          
            449 PRINT_NEWLINE       
            450 JUMP_FORWARD            15 (to 468)

 36     >>  453 LOAD_CONST              42 ('oh,you are wrong!')
            456 PRINT_ITEM          
            457 PRINT_NEWLINE       

 37         458 LOAD_NAME                7 (exit)
            461 LOAD_CONST              32 (0)
            464 CALL_FUNCTION            1
            467 POP_TOP             

 39     >>  468 LOAD_NAME                5 (len)
            471 LOAD_NAME                4 (str)
            474 CALL_FUNCTION            1
            477 STORE_NAME              18 (l)

 40         480 LOAD_NAME                8 (ord)
            483 LOAD_NAME                4 (str)
            486 LOAD_NAME               18 (l)
            489 LOAD_CONST              43 (7)
            492 BINARY_SUBTRACT     
            493 BINARY_SUBSCR       
            494 CALL_FUNCTION            1
            497 STORE_NAME              19 (a1)

 41         500 LOAD_NAME                8 (ord)
            503 LOAD_NAME                4 (str)
            506 LOAD_NAME               18 (l)
            509 LOAD_CONST               4 (6)
            512 BINARY_SUBTRACT     
            513 BINARY_SUBSCR       
            514 CALL_FUNCTION            1
            517 STORE_NAME              20 (a2)

 42         520 LOAD_NAME                8 (ord)
            523 LOAD_NAME                4 (str)
            526 LOAD_NAME               18 (l)
            529 LOAD_CONST              40 (5)
            532 BINARY_SUBTRACT     
            533 BINARY_SUBSCR       
            534 CALL_FUNCTION            1
            537 STORE_NAME              21 (a3)

 43         540 LOAD_NAME                8 (ord)
            543 LOAD_NAME                4 (str)
            546 LOAD_NAME               18 (l)
            549 LOAD_CONST              36 (4)
            552 BINARY_SUBTRACT     
            553 BINARY_SUBSCR       
            554 CALL_FUNCTION            1
            557 STORE_NAME              22 (a4)

 44         560 LOAD_NAME                8 (ord)
            563 LOAD_NAME                4 (str)
            566 LOAD_NAME               18 (l)
            569 LOAD_CONST               0 (3)
            572 BINARY_SUBTRACT     
            573 BINARY_SUBSCR       
            574 CALL_FUNCTION            1
            577 STORE_NAME              23 (a5)

 45         580 LOAD_NAME                8 (ord)
            583 LOAD_NAME                4 (str)
            586 LOAD_NAME               18 (l)
            589 LOAD_CONST              35 (2)
            592 BINARY_SUBTRACT     
            593 BINARY_SUBSCR       
            594 CALL_FUNCTION            1
            597 STORE_NAME              24 (a6)

 46         600 LOAD_NAME               19 (a1)
            603 LOAD_CONST               0 (3)
            606 BINARY_MULTIPLY     
            607 LOAD_NAME               20 (a2)
            610 LOAD_CONST              35 (2)
            613 BINARY_MULTIPLY     
            614 BINARY_ADD          
            615 LOAD_NAME               21 (a3)
            618 LOAD_CONST              40 (5)
            621 BINARY_MULTIPLY     
            622 BINARY_ADD          
            623 LOAD_CONST              44 (1003)
            626 COMPARE_OP               2 (==)
            629 POP_JUMP_IF_FALSE      807

 47         632 LOAD_NAME               19 (a1)
            635 LOAD_CONST              36 (4)
            638 BINARY_MULTIPLY     
            639 LOAD_NAME               20 (a2)
            642 LOAD_CONST              43 (7)
            645 BINARY_MULTIPLY     
            646 BINARY_ADD          
            647 LOAD_NAME               21 (a3)
            650 LOAD_CONST               3 (9)
            653 BINARY_MULTIPLY     
            654 BINARY_ADD          
            655 LOAD_CONST              45 (2013)
            658 COMPARE_OP               2 (==)
            661 POP_JUMP_IF_FALSE      807

 48         664 LOAD_NAME               19 (a1)
            667 LOAD_NAME               20 (a2)
            670 LOAD_CONST              46 (8)
            673 BINARY_MULTIPLY     
            674 BINARY_ADD          
            675 LOAD_NAME               21 (a3)
            678 LOAD_CONST              35 (2)
            681 BINARY_MULTIPLY     
            682 BINARY_ADD          
            683 LOAD_CONST              47 (1109)
            686 COMPARE_OP               2 (==)
            689 POP_JUMP_IF_FALSE      804

 49         692 LOAD_NAME               22 (a4)
            695 LOAD_CONST               0 (3)
            698 BINARY_MULTIPLY     
            699 LOAD_NAME               23 (a5)
            702 LOAD_CONST              35 (2)
            705 BINARY_MULTIPLY     
            706 BINARY_ADD          
            707 LOAD_NAME               24 (a6)
            710 LOAD_CONST              40 (5)
            713 BINARY_MULTIPLY     
            714 BINARY_ADD          
            715 LOAD_CONST              48 (671)
            718 COMPARE_OP               2 (==)
            721 POP_JUMP_IF_FALSE      801

 50         724 LOAD_NAME               22 (a4)
            727 LOAD_CONST              36 (4)
            730 BINARY_MULTIPLY     
            731 LOAD_NAME               23 (a5)
            734 LOAD_CONST              43 (7)
            737 BINARY_MULTIPLY     
            738 BINARY_ADD          
            739 LOAD_NAME               24 (a6)
            742 LOAD_CONST               3 (9)
            745 BINARY_MULTIPLY     
            746 BINARY_ADD          
            747 LOAD_CONST              49 (1252)
            750 COMPARE_OP               2 (==)
            753 POP_JUMP_IF_FALSE      798

 51         756 LOAD_NAME               22 (a4)
            759 LOAD_NAME               23 (a5)
            762 LOAD_CONST              46 (8)
            765 BINARY_MULTIPLY     
            766 BINARY_ADD          
            767 LOAD_NAME               24 (a6)
            770 LOAD_CONST              35 (2)
            773 BINARY_MULTIPLY     
            774 BINARY_ADD          
            775 LOAD_CONST              50 (644)
            778 COMPARE_OP               2 (==)
            781 POP_JUMP_IF_FALSE      795

 52         784 LOAD_CONST              51 ('congraduation!you get the right flag!')
            787 PRINT_ITEM          
            788 PRINT_NEWLINE       
            789 JUMP_ABSOLUTE          795
            792 JUMP_ABSOLUTE          798
        >>  795 JUMP_ABSOLUTE          801
        >>  798 JUMP_ABSOLUTE          804
        >>  801 JUMP_ABSOLUTE          807
        >>  804 JUMP_FORWARD             0 (to 807)
        >>  807 LOAD_CONST              52 (None)
            810 RETURN_VALUE 

还原后的源代码逻辑大概如下(dis模块可查看python字节码反汇编伪代码,方便与题目校对):

import dis


def main():
	en = [3, 37, 72, 9, 6, 132]
	output = [101, 96, 23,68,112,42,107,62,96,53,176,179,98,53,67,29,41,120,60,106,51,101,178,189,101,48]
	print('welcome to GWHT2020')
	flag = input('please input your flag:')
	str = flag
	a = len(str)
	if a < 38:
		print('lenth wrong')
		exit(0)
	else:
		if (((ord(str[0]) * 2020 +  ord(str[1])) * 2020 + ord(str[2]))*2020 + ord(str[3])) * 2020 + ord(str[4]) == 1182843538814603:
			print('good!continuexe2x80xa6xe2x80xa6')
		else:
			print('bye~')
			exit(0)
		x = []
		k = 5
		for i in range(13):
			b = ord(str[k])
			c = ord(str[k+1])
			a11 = c ^ en[i%6]
			a22 = b ^ en[i%6]
			x.append(a11)
			x.append(a22)
			k = k + 2
		if x == output:
			print('good!continuexe2x80xa6xe2x80xa6')
		else:
			print('oh,you are wrong!')
			exit(0)
		l = len(str)
		a1 = ord(str[l-7])
		a2 = ord(str[l-6])
		a3 = ord(str[l-5])
		a4 = ord(str[l-4])
		a5 = ord(str[l-3])
		a6 = ord(str[l-2])
		if a1 * 3 + a2 * 2 + a3 * 5 == 1003:
			pass
		else:
			print('wrong')
		if a1 * 4 + a2 * 7 + a3 * 9 == 2013:
			pass
		else:
			print('wrong')
		if a1 + a2 * 8 + a3 * 2 == 1109:
			pass
		else:
			print('wrong')
		if a4 * 3 + a5 * 2 + a6 * 5 == 671:
			pass
		else:
			print('wrong')
		if a4 * 4 + a5 * 7 + a6 * 9 == 1252:
			pass
		else:
			print('wrong')
		if a4 + a5 * 8 + a6 * 2 == 644:
			print('congratulations!')
		else:
			print('wrong')


print(dis.dis(main))
main()

脚本如下:


from z3 import *

a1 = Int('a1')
a2 = Int('a2')
a3 = Int('a3')
a4 = Int('a4')
a5 = Int('a5')
a6 = Int('a6')

s = Solver()

s.add(a1 * 3 + a2 * 2 + a3 * 5 == 1003)
s.add(a1 * 4 + a2 * 7 + a3 * 9 == 2013)
s.add(a1 + a2 * 8 + a3 * 2 == 1109)
s.add(a4 * 3 + a5 * 2 + a6 * 5 == 671)
s.add(a4 * 4 + a5 * 7 + a6 * 9 == 1252)
s.add(a4 + a5 * 8 + a6 * 2 == 644)

print(s.check())
m = s.model()
print ("traversing model...")
for d in m.decls():
    print("{} = {}".format(d.name(), (m[d])))
a = [55,101,51,102,102,97]
for i in a:
	print(chr(i))

a5 = 55
a2 = 101
a6 = 51
a3 = 102
a4 = 102
a1 = 97

for i in range(32,128):
	for j in range(32,128):
		for k in range(32,128):
			for l in range(32,128):
				for m in range(32,128):
					if (((i * 2020 +  j) * 2020 + k)*2020 + l) * 2020 + m == 1182843538814603:
						print(i ,' ',j,' ',k,' ',l,' ',m)
						exit(0)

# 第6~31个字符
output = [101, 96, 23,68,112,42,107,62,96,53,176,179,98,53,67,29,41,120,60,106,51,101,178,189,101,48]
k = 0
out_put = []
en = [3, 37, 72, 9, 6, 132]
for i in range(13):
    out_put.append(output[k+1] ^ en[i%6])
    out_put.append(output[k] ^ en[i%6])    
    k += 2

a = 'GWHT{'
flag = []
for i in a:
	flag.append(ord(i))

for i in out_put:
	flag.append(i)

flag.append(a1)
flag.append(a2)
flag.append(a3)
flag.append(a4)
flag.append(a5)
flag.append(a6)

for i in flag:
	print(chr(i), end= '')
print('}')
原文地址:https://www.cnblogs.com/pluie/p/13667665.html