华为xctf第二场

我一直用的都是华为手机啊（逃

realworld

aes

nc上之后先求一个后缀使得整体的md5的后20bit为0，防止服务器遭爆破。

服务端是python写的，每次都会随机生成一个key，然后aes加密已知的明文，把key的前12个字符和密文告诉你（写的程序）。没错，你要通过base64编码上传一个可执行文件。然后这个可执行文件接收输入（key[:12] + ciphertext），然后爆破出后4字节的key并输出。服务端接收这个4byte的输出后进行比较是否正确，如果正常输出flag。

首先是爆破的程序。恰好第一场华为xctf就有一个tiny shell的题目，里面有个aes的代码，直接拿来用。

aes.h

#ifndef _AES_H
#define _AES_H

#ifndef uint8
#define uint8  unsigned char
#endif

#ifndef uint32
#define uint32 unsigned long int
#endif

struct aes_context
{
    int nr;             /* number of rounds */
    uint32 erk[64];     /* encryption round keys */
    uint32 drk[64];     /* decryption round keys */
};

int  aes_set_key( struct aes_context *ctx, uint8 *key, int nbits );
void aes_encrypt( struct aes_context *ctx, uint8 data[16] );
void aes_decrypt( struct aes_context *ctx, uint8 data[16] );

#endif /* aes.h */

aes.c

/*
 * FIPS-197 compliant AES implementation,
 * by Christophe Devine <devine@cr0.net>;
 * this program is licensed under the GPL.
 */

#include "aes.h"

/* forward S-box */

static uint32 FSb[256] =
{
    0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5,
    0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
    0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0,
    0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
    0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC,
    0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
    0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A,
    0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
    0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0,
    0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
    0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B,
    0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
    0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85,
    0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
    0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5,
    0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
    0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17,
    0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
    0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88,
    0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
    0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C,
    0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
    0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9,
    0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
    0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6,
    0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
    0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E,
    0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
    0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94,
    0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
    0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68,
    0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
};

/* forward table */

#define FT \
\
    V(C6,63,63,A5), V(F8,7C,7C,84), V(EE,77,77,99), V(F6,7B,7B,8D), \
    V(FF,F2,F2,0D), V(D6,6B,6B,BD), V(DE,6F,6F,B1), V(91,C5,C5,54), \
    V(60,30,30,50), V(02,01,01,03), V(CE,67,67,A9), V(56,2B,2B,7D), \
    V(E7,FE,FE,19), V(B5,D7,D7,62), V(4D,AB,AB,E6), V(EC,76,76,9A), \
    V(8F,CA,CA,45), V(1F,82,82,9D), V(89,C9,C9,40), V(FA,7D,7D,87), \
    V(EF,FA,FA,15), V(B2,59,59,EB), V(8E,47,47,C9), V(FB,F0,F0,0B), \
    V(41,AD,AD,EC), V(B3,D4,D4,67), V(5F,A2,A2,FD), V(45,AF,AF,EA), \
    V(23,9C,9C,BF), V(53,A4,A4,F7), V(E4,72,72,96), V(9B,C0,C0,5B), \
    V(75,B7,B7,C2), V(E1,FD,FD,1C), V(3D,93,93,AE), V(4C,26,26,6A), \
    V(6C,36,36,5A), V(7E,3F,3F,41), V(F5,F7,F7,02), V(83,CC,CC,4F), \
    V(68,34,34,5C), V(51,A5,A5,F4), V(D1,E5,E5,34), V(F9,F1,F1,08), \
    V(E2,71,71,93), V(AB,D8,D8,73), V(62,31,31,53), V(2A,15,15,3F), \
    V(08,04,04,0C), V(95,C7,C7,52), V(46,23,23,65), V(9D,C3,C3,5E), \
    V(30,18,18,28), V(37,96,96,A1), V(0A,05,05,0F), V(2F,9A,9A,B5), \
    V(0E,07,07,09), V(24,12,12,36), V(1B,80,80,9B), V(DF,E2,E2,3D), \
    V(CD,EB,EB,26), V(4E,27,27,69), V(7F,B2,B2,CD), V(EA,75,75,9F), \
    V(12,09,09,1B), V(1D,83,83,9E), V(58,2C,2C,74), V(34,1A,1A,2E), \
    V(36,1B,1B,2D), V(DC,6E,6E,B2), V(B4,5A,5A,EE), V(5B,A0,A0,FB), \
    V(A4,52,52,F6), V(76,3B,3B,4D), V(B7,D6,D6,61), V(7D,B3,B3,CE), \
    V(52,29,29,7B), V(DD,E3,E3,3E), V(5E,2F,2F,71), V(13,84,84,97), \
    V(A6,53,53,F5), V(B9,D1,D1,68), V(00,00,00,00), V(C1,ED,ED,2C), \
    V(40,20,20,60), V(E3,FC,FC,1F), V(79,B1,B1,C8), V(B6,5B,5B,ED), \
    V(D4,6A,6A,BE), V(8D,CB,CB,46), V(67,BE,BE,D9), V(72,39,39,4B), \
    V(94,4A,4A,DE), V(98,4C,4C,D4), V(B0,58,58,E8), V(85,CF,CF,4A), \
    V(BB,D0,D0,6B), V(C5,EF,EF,2A), V(4F,AA,AA,E5), V(ED,FB,FB,16), \
    V(86,43,43,C5), V(9A,4D,4D,D7), V(66,33,33,55), V(11,85,85,94), \
    V(8A,45,45,CF), V(E9,F9,F9,10), V(04,02,02,06), V(FE,7F,7F,81), \
    V(A0,50,50,F0), V(78,3C,3C,44), V(25,9F,9F,BA), V(4B,A8,A8,E3), \
    V(A2,51,51,F3), V(5D,A3,A3,FE), V(80,40,40,C0), V(05,8F,8F,8A), \
    V(3F,92,92,AD), V(21,9D,9D,BC), V(70,38,38,48), V(F1,F5,F5,04), \
    V(63,BC,BC,DF), V(77,B6,B6,C1), V(AF,DA,DA,75), V(42,21,21,63), \
    V(20,10,10,30), V(E5,FF,FF,1A), V(FD,F3,F3,0E), V(BF,D2,D2,6D), \
    V(81,CD,CD,4C), V(18,0C,0C,14), V(26,13,13,35), V(C3,EC,EC,2F), \
    V(BE,5F,5F,E1), V(35,97,97,A2), V(88,44,44,CC), V(2E,17,17,39), \
    V(93,C4,C4,57), V(55,A7,A7,F2), V(FC,7E,7E,82), V(7A,3D,3D,47), \
    V(C8,64,64,AC), V(BA,5D,5D,E7), V(32,19,19,2B), V(E6,73,73,95), \
    V(C0,60,60,A0), V(19,81,81,98), V(9E,4F,4F,D1), V(A3,DC,DC,7F), \
    V(44,22,22,66), V(54,2A,2A,7E), V(3B,90,90,AB), V(0B,88,88,83), \
    V(8C,46,46,CA), V(C7,EE,EE,29), V(6B,B8,B8,D3), V(28,14,14,3C), \
    V(A7,DE,DE,79), V(BC,5E,5E,E2), V(16,0B,0B,1D), V(AD,DB,DB,76), \
    V(DB,E0,E0,3B), V(64,32,32,56), V(74,3A,3A,4E), V(14,0A,0A,1E), \
    V(92,49,49,DB), V(0C,06,06,0A), V(48,24,24,6C), V(B8,5C,5C,E4), \
    V(9F,C2,C2,5D), V(BD,D3,D3,6E), V(43,AC,AC,EF), V(C4,62,62,A6), \
    V(39,91,91,A8), V(31,95,95,A4), V(D3,E4,E4,37), V(F2,79,79,8B), \
    V(D5,E7,E7,32), V(8B,C8,C8,43), V(6E,37,37,59), V(DA,6D,6D,B7), \
    V(01,8D,8D,8C), V(B1,D5,D5,64), V(9C,4E,4E,D2), V(49,A9,A9,E0), \
    V(D8,6C,6C,B4), V(AC,56,56,FA), V(F3,F4,F4,07), V(CF,EA,EA,25), \
    V(CA,65,65,AF), V(F4,7A,7A,8E), V(47,AE,AE,E9), V(10,08,08,18), \
    V(6F,BA,BA,D5), V(F0,78,78,88), V(4A,25,25,6F), V(5C,2E,2E,72), \
    V(38,1C,1C,24), V(57,A6,A6,F1), V(73,B4,B4,C7), V(97,C6,C6,51), \
    V(CB,E8,E8,23), V(A1,DD,DD,7C), V(E8,74,74,9C), V(3E,1F,1F,21), \
    V(96,4B,4B,DD), V(61,BD,BD,DC), V(0D,8B,8B,86), V(0F,8A,8A,85), \
    V(E0,70,70,90), V(7C,3E,3E,42), V(71,B5,B5,C4), V(CC,66,66,AA), \
    V(90,48,48,D8), V(06,03,03,05), V(F7,F6,F6,01), V(1C,0E,0E,12), \
    V(C2,61,61,A3), V(6A,35,35,5F), V(AE,57,57,F9), V(69,B9,B9,D0), \
    V(17,86,86,91), V(99,C1,C1,58), V(3A,1D,1D,27), V(27,9E,9E,B9), \
    V(D9,E1,E1,38), V(EB,F8,F8,13), V(2B,98,98,B3), V(22,11,11,33), \
    V(D2,69,69,BB), V(A9,D9,D9,70), V(07,8E,8E,89), V(33,94,94,A7), \
    V(2D,9B,9B,B6), V(3C,1E,1E,22), V(15,87,87,92), V(C9,E9,E9,20), \
    V(87,CE,CE,49), V(AA,55,55,FF), V(50,28,28,78), V(A5,DF,DF,7A), \
    V(03,8C,8C,8F), V(59,A1,A1,F8), V(09,89,89,80), V(1A,0D,0D,17), \
    V(65,BF,BF,DA), V(D7,E6,E6,31), V(84,42,42,C6), V(D0,68,68,B8), \
    V(82,41,41,C3), V(29,99,99,B0), V(5A,2D,2D,77), V(1E,0F,0F,11), \
    V(7B,B0,B0,CB), V(A8,54,54,FC), V(6D,BB,BB,D6), V(2C,16,16,3A)

#define V(a,b,c,d) 0x##a##b##c##d
static uint32 FT0[256] = { FT };
#undef V

#define V(a,b,c,d) 0x##d##a##b##c
static uint32 FT1[256] = { FT };
#undef V

#define V(a,b,c,d) 0x##c##d##a##b
static uint32 FT2[256] = { FT };
#undef V

#define V(a,b,c,d) 0x##b##c##d##a
static uint32 FT3[256] = { FT };
#undef V

/* reverse S-box */

static uint32 RSb[256] =
{
    0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38,
    0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
    0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87,
    0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
    0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D,
    0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
    0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2,
    0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
    0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16,
    0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
    0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA,
    0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
    0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A,
    0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
    0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02,
    0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
    0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA,
    0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
    0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85,
    0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
    0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89,
    0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
    0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20,
    0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
    0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31,
    0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
    0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D,
    0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
    0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0,
    0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
    0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26,
    0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
};

/* reverse table */

#define RT \
\
    V(51,F4,A7,50), V(7E,41,65,53), V(1A,17,A4,C3), V(3A,27,5E,96), \
    V(3B,AB,6B,CB), V(1F,9D,45,F1), V(AC,FA,58,AB), V(4B,E3,03,93), \
    V(20,30,FA,55), V(AD,76,6D,F6), V(88,CC,76,91), V(F5,02,4C,25), \
    V(4F,E5,D7,FC), V(C5,2A,CB,D7), V(26,35,44,80), V(B5,62,A3,8F), \
    V(DE,B1,5A,49), V(25,BA,1B,67), V(45,EA,0E,98), V(5D,FE,C0,E1), \
    V(C3,2F,75,02), V(81,4C,F0,12), V(8D,46,97,A3), V(6B,D3,F9,C6), \
    V(03,8F,5F,E7), V(15,92,9C,95), V(BF,6D,7A,EB), V(95,52,59,DA), \
    V(D4,BE,83,2D), V(58,74,21,D3), V(49,E0,69,29), V(8E,C9,C8,44), \
    V(75,C2,89,6A), V(F4,8E,79,78), V(99,58,3E,6B), V(27,B9,71,DD), \
    V(BE,E1,4F,B6), V(F0,88,AD,17), V(C9,20,AC,66), V(7D,CE,3A,B4), \
    V(63,DF,4A,18), V(E5,1A,31,82), V(97,51,33,60), V(62,53,7F,45), \
    V(B1,64,77,E0), V(BB,6B,AE,84), V(FE,81,A0,1C), V(F9,08,2B,94), \
    V(70,48,68,58), V(8F,45,FD,19), V(94,DE,6C,87), V(52,7B,F8,B7), \
    V(AB,73,D3,23), V(72,4B,02,E2), V(E3,1F,8F,57), V(66,55,AB,2A), \
    V(B2,EB,28,07), V(2F,B5,C2,03), V(86,C5,7B,9A), V(D3,37,08,A5), \
    V(30,28,87,F2), V(23,BF,A5,B2), V(02,03,6A,BA), V(ED,16,82,5C), \
    V(8A,CF,1C,2B), V(A7,79,B4,92), V(F3,07,F2,F0), V(4E,69,E2,A1), \
    V(65,DA,F4,CD), V(06,05,BE,D5), V(D1,34,62,1F), V(C4,A6,FE,8A), \
    V(34,2E,53,9D), V(A2,F3,55,A0), V(05,8A,E1,32), V(A4,F6,EB,75), \
    V(0B,83,EC,39), V(40,60,EF,AA), V(5E,71,9F,06), V(BD,6E,10,51), \
    V(3E,21,8A,F9), V(96,DD,06,3D), V(DD,3E,05,AE), V(4D,E6,BD,46), \
    V(91,54,8D,B5), V(71,C4,5D,05), V(04,06,D4,6F), V(60,50,15,FF), \
    V(19,98,FB,24), V(D6,BD,E9,97), V(89,40,43,CC), V(67,D9,9E,77), \
    V(B0,E8,42,BD), V(07,89,8B,88), V(E7,19,5B,38), V(79,C8,EE,DB), \
    V(A1,7C,0A,47), V(7C,42,0F,E9), V(F8,84,1E,C9), V(00,00,00,00), \
    V(09,80,86,83), V(32,2B,ED,48), V(1E,11,70,AC), V(6C,5A,72,4E), \
    V(FD,0E,FF,FB), V(0F,85,38,56), V(3D,AE,D5,1E), V(36,2D,39,27), \
    V(0A,0F,D9,64), V(68,5C,A6,21), V(9B,5B,54,D1), V(24,36,2E,3A), \
    V(0C,0A,67,B1), V(93,57,E7,0F), V(B4,EE,96,D2), V(1B,9B,91,9E), \
    V(80,C0,C5,4F), V(61,DC,20,A2), V(5A,77,4B,69), V(1C,12,1A,16), \
    V(E2,93,BA,0A), V(C0,A0,2A,E5), V(3C,22,E0,43), V(12,1B,17,1D), \
    V(0E,09,0D,0B), V(F2,8B,C7,AD), V(2D,B6,A8,B9), V(14,1E,A9,C8), \
    V(57,F1,19,85), V(AF,75,07,4C), V(EE,99,DD,BB), V(A3,7F,60,FD), \
    V(F7,01,26,9F), V(5C,72,F5,BC), V(44,66,3B,C5), V(5B,FB,7E,34), \
    V(8B,43,29,76), V(CB,23,C6,DC), V(B6,ED,FC,68), V(B8,E4,F1,63), \
    V(D7,31,DC,CA), V(42,63,85,10), V(13,97,22,40), V(84,C6,11,20), \
    V(85,4A,24,7D), V(D2,BB,3D,F8), V(AE,F9,32,11), V(C7,29,A1,6D), \
    V(1D,9E,2F,4B), V(DC,B2,30,F3), V(0D,86,52,EC), V(77,C1,E3,D0), \
    V(2B,B3,16,6C), V(A9,70,B9,99), V(11,94,48,FA), V(47,E9,64,22), \
    V(A8,FC,8C,C4), V(A0,F0,3F,1A), V(56,7D,2C,D8), V(22,33,90,EF), \
    V(87,49,4E,C7), V(D9,38,D1,C1), V(8C,CA,A2,FE), V(98,D4,0B,36), \
    V(A6,F5,81,CF), V(A5,7A,DE,28), V(DA,B7,8E,26), V(3F,AD,BF,A4), \
    V(2C,3A,9D,E4), V(50,78,92,0D), V(6A,5F,CC,9B), V(54,7E,46,62), \
    V(F6,8D,13,C2), V(90,D8,B8,E8), V(2E,39,F7,5E), V(82,C3,AF,F5), \
    V(9F,5D,80,BE), V(69,D0,93,7C), V(6F,D5,2D,A9), V(CF,25,12,B3), \
    V(C8,AC,99,3B), V(10,18,7D,A7), V(E8,9C,63,6E), V(DB,3B,BB,7B), \
    V(CD,26,78,09), V(6E,59,18,F4), V(EC,9A,B7,01), V(83,4F,9A,A8), \
    V(E6,95,6E,65), V(AA,FF,E6,7E), V(21,BC,CF,08), V(EF,15,E8,E6), \
    V(BA,E7,9B,D9), V(4A,6F,36,CE), V(EA,9F,09,D4), V(29,B0,7C,D6), \
    V(31,A4,B2,AF), V(2A,3F,23,31), V(C6,A5,94,30), V(35,A2,66,C0), \
    V(74,4E,BC,37), V(FC,82,CA,A6), V(E0,90,D0,B0), V(33,A7,D8,15), \
    V(F1,04,98,4A), V(41,EC,DA,F7), V(7F,CD,50,0E), V(17,91,F6,2F), \
    V(76,4D,D6,8D), V(43,EF,B0,4D), V(CC,AA,4D,54), V(E4,96,04,DF), \
    V(9E,D1,B5,E3), V(4C,6A,88,1B), V(C1,2C,1F,B8), V(46,65,51,7F), \
    V(9D,5E,EA,04), V(01,8C,35,5D), V(FA,87,74,73), V(FB,0B,41,2E), \
    V(B3,67,1D,5A), V(92,DB,D2,52), V(E9,10,56,33), V(6D,D6,47,13), \
    V(9A,D7,61,8C), V(37,A1,0C,7A), V(59,F8,14,8E), V(EB,13,3C,89), \
    V(CE,A9,27,EE), V(B7,61,C9,35), V(E1,1C,E5,ED), V(7A,47,B1,3C), \
    V(9C,D2,DF,59), V(55,F2,73,3F), V(18,14,CE,79), V(73,C7,37,BF), \
    V(53,F7,CD,EA), V(5F,FD,AA,5B), V(DF,3D,6F,14), V(78,44,DB,86), \
    V(CA,AF,F3,81), V(B9,68,C4,3E), V(38,24,34,2C), V(C2,A3,40,5F), \
    V(16,1D,C3,72), V(BC,E2,25,0C), V(28,3C,49,8B), V(FF,0D,95,41), \
    V(39,A8,01,71), V(08,0C,B3,DE), V(D8,B4,E4,9C), V(64,56,C1,90), \
    V(7B,CB,84,61), V(D5,32,B6,70), V(48,6C,5C,74), V(D0,B8,57,42)

#define V(a,b,c,d) 0x##a##b##c##d
static uint32 RT0[256] = { RT };
#undef V

#define V(a,b,c,d) 0x##d##a##b##c
static uint32 RT1[256] = { RT };
#undef V

#define V(a,b,c,d) 0x##c##d##a##b
static uint32 RT2[256] = { RT };
#undef V

#define V(a,b,c,d) 0x##b##c##d##a
static uint32 RT3[256] = { RT };
#undef V

/* round constants */

static uint32 RCON[10] =
{
    0x01000000, 0x02000000, 0x04000000, 0x08000000,
    0x10000000, 0x20000000, 0x40000000, 0x80000000,
    0x1B000000, 0x36000000
};

/* platform-independant 32-bit integer manipulation macros */

#define GET_UINT32(n,b,i)                       \
{                                               \
    (n) = ( (uint32) (b)[(i)    ] << 24 )       \
        | ( (uint32) (b)[(i) + 1] << 16 )       \
        | ( (uint32) (b)[(i) + 2] <<  8 )       \
        | ( (uint32) (b)[(i) + 3]       );      \
}

#define PUT_UINT32(n,b,i)                       \
{                                               \
    (b)[(i)    ] = (uint8) ( (n) >> 24 );       \
    (b)[(i) + 1] = (uint8) ( (n) >> 16 );       \
    (b)[(i) + 2] = (uint8) ( (n) >>  8 );       \
    (b)[(i) + 3] = (uint8) ( (n)       );       \
}

/* key scheduling routine */

int aes_set_key( struct aes_context *ctx, uint8 *key, int nbits )
{
    int i;
    uint32 *RK;

    switch( nbits )
    {
        case 128: ctx->nr = 10; break;
        case 192: ctx->nr = 12; break;
        case 256: ctx->nr = 14; break;
        default : return( 1 );
    }

    RK = ctx->erk;

    for( i = 0; i < (nbits >> 5); i++ )
    {
        GET_UINT32( RK[i], key, i * 4 );
    }

    /* setup encryption round keys */

    switch( nbits )
    {
    case 128:

        for( i = 0; i < 10; i++, RK += 4 )
        {
            RK[4]  = RK[0] ^ RCON[i] ^
                        ( FSb[ (uint8) ( RK[3] >> 16 ) ] << 24 ) ^
                        ( FSb[ (uint8) ( RK[3] >>  8 ) ] << 16 ) ^
                        ( FSb[ (uint8) ( RK[3]       ) ] <<  8 ) ^
                        ( FSb[ (uint8) ( RK[3] >> 24 ) ]       );

            RK[5]  = RK[1] ^ RK[4];
            RK[6]  = RK[2] ^ RK[5];
            RK[7]  = RK[3] ^ RK[6];
        }
        break;

    case 192:

        for( i = 0; i < 8; i++, RK += 6 )
        {
            RK[6]  = RK[0] ^ RCON[i] ^
                        ( FSb[ (uint8) ( RK[5] >> 16 ) ] << 24 ) ^
                        ( FSb[ (uint8) ( RK[5] >>  8 ) ] << 16 ) ^
                        ( FSb[ (uint8) ( RK[5]       ) ] <<  8 ) ^
                        ( FSb[ (uint8) ( RK[5] >> 24 ) ]       );

            RK[7]  = RK[1] ^ RK[6];
            RK[8]  = RK[2] ^ RK[7];
            RK[9]  = RK[3] ^ RK[8];
            RK[10] = RK[4] ^ RK[9];
            RK[11] = RK[5] ^ RK[10];
        }
        break;

    case 256:

        for( i = 0; i < 7; i++, RK += 8 )
        {
            RK[8]  = RK[0] ^ RCON[i] ^
                        ( FSb[ (uint8) ( RK[7] >> 16 ) ] << 24 ) ^
                        ( FSb[ (uint8) ( RK[7] >>  8 ) ] << 16 ) ^
                        ( FSb[ (uint8) ( RK[7]       ) ] <<  8 ) ^
                        ( FSb[ (uint8) ( RK[7] >> 24 ) ]       );

            RK[9]  = RK[1] ^ RK[8];
            RK[10] = RK[2] ^ RK[9];
            RK[11] = RK[3] ^ RK[10];

            RK[12] = RK[4] ^
                        ( FSb[ (uint8) ( RK[11] >> 24 ) ] << 24 ) ^
                        ( FSb[ (uint8) ( RK[11] >> 16 ) ] << 16 ) ^
                        ( FSb[ (uint8) ( RK[11] >>  8 ) ] <<  8 ) ^
                        ( FSb[ (uint8) ( RK[11]       ) ]       );

            RK[13] = RK[5] ^ RK[12];
            RK[14] = RK[6] ^ RK[13];
            RK[15] = RK[7] ^ RK[14];
        }
        break;
    }

    /* setup decryption round keys */

    for( i = 0; i <= ctx->nr; i++ )
    {
        ctx->drk[i * 4    ] = ctx->erk[( ctx->nr - i ) * 4    ];
        ctx->drk[i * 4 + 1] = ctx->erk[( ctx->nr - i ) * 4 + 1];
        ctx->drk[i * 4 + 2] = ctx->erk[( ctx->nr - i ) * 4 + 2];
        ctx->drk[i * 4 + 3] = ctx->erk[( ctx->nr - i ) * 4 + 3];
    }

    for( i = 1, RK = ctx->drk + 4; i < ctx->nr; i++, RK += 4 )
    {
        RK[0] = RT0[ FSb[ (uint8) ( RK[0] >> 24 ) ] ] ^
                RT1[ FSb[ (uint8) ( RK[0] >> 16 ) ] ] ^
                RT2[ FSb[ (uint8) ( RK[0] >>  8 ) ] ] ^
                RT3[ FSb[ (uint8) ( RK[0]       ) ] ];

        RK[1] = RT0[ FSb[ (uint8) ( RK[1] >> 24 ) ] ] ^
                RT1[ FSb[ (uint8) ( RK[1] >> 16 ) ] ] ^
                RT2[ FSb[ (uint8) ( RK[1] >>  8 ) ] ] ^
                RT3[ FSb[ (uint8) ( RK[1]       ) ] ];

        RK[2] = RT0[ FSb[ (uint8) ( RK[2] >> 24 ) ] ] ^
                RT1[ FSb[ (uint8) ( RK[2] >> 16 ) ] ] ^
                RT2[ FSb[ (uint8) ( RK[2] >>  8 ) ] ] ^
                RT3[ FSb[ (uint8) ( RK[2]       ) ] ];

        RK[3] = RT0[ FSb[ (uint8) ( RK[3] >> 24 ) ] ] ^
                RT1[ FSb[ (uint8) ( RK[3] >> 16 ) ] ] ^
                RT2[ FSb[ (uint8) ( RK[3] >>  8 ) ] ] ^
                RT3[ FSb[ (uint8) ( RK[3]       ) ] ];
    }

    return( 0 );
}

/* 128-bit block encryption routine */

void aes_encrypt( struct aes_context *ctx, uint8 data[16] )
{
    uint32 *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;

    RK = ctx->erk;

    GET_UINT32( X0, data,  0 ); X0 ^= RK[0];
    GET_UINT32( X1, data,  4 ); X1 ^= RK[1];
    GET_UINT32( X2, data,  8 ); X2 ^= RK[2];
    GET_UINT32( X3, data, 12 ); X3 ^= RK[3];

#define FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)         \
{                                               \
    RK += 4;                                    \
                                                \
    X0 = RK[0] ^ FT0[ (uint8) ( Y0 >> 24 ) ] ^  \
                 FT1[ (uint8) ( Y1 >> 16 ) ] ^  \
                 FT2[ (uint8) ( Y2 >>  8 ) ] ^  \
                 FT3[ (uint8) ( Y3       ) ];   \
                                                \
    X1 = RK[1] ^ FT0[ (uint8) ( Y1 >> 24 ) ] ^  \
                 FT1[ (uint8) ( Y2 >> 16 ) ] ^  \
                 FT2[ (uint8) ( Y3 >>  8 ) ] ^  \
                 FT3[ (uint8) ( Y0       ) ];   \
                                                \
    X2 = RK[2] ^ FT0[ (uint8) ( Y2 >> 24 ) ] ^  \
                 FT1[ (uint8) ( Y3 >> 16 ) ] ^  \
                 FT2[ (uint8) ( Y0 >>  8 ) ] ^  \
                 FT3[ (uint8) ( Y1       ) ];   \
                                                \
    X3 = RK[3] ^ FT0[ (uint8) ( Y3 >> 24 ) ] ^  \
                 FT1[ (uint8) ( Y0 >> 16 ) ] ^  \
                 FT2[ (uint8) ( Y1 >>  8 ) ] ^  \
                 FT3[ (uint8) ( Y2       ) ];   \
}

    FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 1 */
    FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );           /* round 2 */
    FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 3 */
    FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );           /* round 4 */
    FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 5 */
    FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );           /* round 6 */
    FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 7 */
    FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );           /* round 8 */
    FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 9 */

    if( ctx->nr > 10 )
    {
        FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );       /* round 10 */
        FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );       /* round 11 */
    }

    if( ctx->nr > 12 )
    {
        FROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );       /* round 12 */
        FROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );       /* round 13 */
    }

    /* last round */

    RK += 4;

    X0 = RK[0] ^ ( FSb[ (uint8) ( Y0 >> 24 ) ] << 24 ) ^
                 ( FSb[ (uint8) ( Y1 >> 16 ) ] << 16 ) ^
                 ( FSb[ (uint8) ( Y2 >>  8 ) ] <<  8 ) ^
                 ( FSb[ (uint8) ( Y3       ) ]       );

    X1 = RK[1] ^ ( FSb[ (uint8) ( Y1 >> 24 ) ] << 24 ) ^
                 ( FSb[ (uint8) ( Y2 >> 16 ) ] << 16 ) ^
                 ( FSb[ (uint8) ( Y3 >>  8 ) ] <<  8 ) ^
                 ( FSb[ (uint8) ( Y0       ) ]       );

    X2 = RK[2] ^ ( FSb[ (uint8) ( Y2 >> 24 ) ] << 24 ) ^
                 ( FSb[ (uint8) ( Y3 >> 16 ) ] << 16 ) ^
                 ( FSb[ (uint8) ( Y0 >>  8 ) ] <<  8 ) ^
                 ( FSb[ (uint8) ( Y1       ) ]       );

    X3 = RK[3] ^ ( FSb[ (uint8) ( Y3 >> 24 ) ] << 24 ) ^
                 ( FSb[ (uint8) ( Y0 >> 16 ) ] << 16 ) ^
                 ( FSb[ (uint8) ( Y1 >>  8 ) ] <<  8 ) ^
                 ( FSb[ (uint8) ( Y2       ) ]       );

    PUT_UINT32( X0, data,  0 );
    PUT_UINT32( X1, data,  4 );
    PUT_UINT32( X2, data,  8 );
    PUT_UINT32( X3, data, 12 );
}

/* 128-bit block decryption routine */

void aes_decrypt( struct aes_context *ctx, uint8 data[16] )
{
    uint32 *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;

    RK = ctx->drk;

    GET_UINT32( X0, data,  0 ); X0 ^= RK[0];
    GET_UINT32( X1, data,  4 ); X1 ^= RK[1];
    GET_UINT32( X2, data,  8 ); X2 ^= RK[2];
    GET_UINT32( X3, data, 12 ); X3 ^= RK[3];

#define RROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)         \
{                                               \
    RK += 4;                                    \
                                                \
    X0 = RK[0] ^ RT0[ (uint8) ( Y0 >> 24 ) ] ^  \
                 RT1[ (uint8) ( Y3 >> 16 ) ] ^  \
                 RT2[ (uint8) ( Y2 >>  8 ) ] ^  \
                 RT3[ (uint8) ( Y1       ) ];   \
                                                \
    X1 = RK[1] ^ RT0[ (uint8) ( Y1 >> 24 ) ] ^  \
                 RT1[ (uint8) ( Y0 >> 16 ) ] ^  \
                 RT2[ (uint8) ( Y3 >>  8 ) ] ^  \
                 RT3[ (uint8) ( Y2       ) ];   \
                                                \
    X2 = RK[2] ^ RT0[ (uint8) ( Y2 >> 24 ) ] ^  \
                 RT1[ (uint8) ( Y1 >> 16 ) ] ^  \
                 RT2[ (uint8) ( Y0 >>  8 ) ] ^  \
                 RT3[ (uint8) ( Y3       ) ];   \
                                                \
    X3 = RK[3] ^ RT0[ (uint8) ( Y3 >> 24 ) ] ^  \
                 RT1[ (uint8) ( Y2 >> 16 ) ] ^  \
                 RT2[ (uint8) ( Y1 >>  8 ) ] ^  \
                 RT3[ (uint8) ( Y0       ) ];   \
}

    RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 1 */
    RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );           /* round 2 */
    RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 3 */
    RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );           /* round 4 */
    RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 5 */
    RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );           /* round 6 */
    RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 7 */
    RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );           /* round 8 */
    RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );           /* round 9 */

    if( ctx->nr > 10 )
    {
        RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );       /* round 10 */
        RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );       /* round 11 */
    }

    if( ctx->nr > 12 )
    {
        RROUND( X0, X1, X2, X3, Y0, Y1, Y2, Y3 );       /* round 12 */
        RROUND( Y0, Y1, Y2, Y3, X0, X1, X2, X3 );       /* round 13 */
    }

    /* last round */

    RK += 4;

    X0 = RK[0] ^ ( RSb[ (uint8) ( Y0 >> 24 ) ] << 24 ) ^
                 ( RSb[ (uint8) ( Y3 >> 16 ) ] << 16 ) ^
                 ( RSb[ (uint8) ( Y2 >>  8 ) ] <<  8 ) ^
                 ( RSb[ (uint8) ( Y1       ) ]       );

    X1 = RK[1] ^ ( RSb[ (uint8) ( Y1 >> 24 ) ] << 24 ) ^
                 ( RSb[ (uint8) ( Y0 >> 16 ) ] << 16 ) ^
                 ( RSb[ (uint8) ( Y3 >>  8 ) ] <<  8 ) ^
                 ( RSb[ (uint8) ( Y2       ) ]       );

    X2 = RK[2] ^ ( RSb[ (uint8) ( Y2 >> 24 ) ] << 24 ) ^
                 ( RSb[ (uint8) ( Y1 >> 16 ) ] << 16 ) ^
                 ( RSb[ (uint8) ( Y0 >>  8 ) ] <<  8 ) ^
                 ( RSb[ (uint8) ( Y3       ) ]       );

    X3 = RK[3] ^ ( RSb[ (uint8) ( Y3 >> 24 ) ] << 24 ) ^
                 ( RSb[ (uint8) ( Y2 >> 16 ) ] << 16 ) ^
                 ( RSb[ (uint8) ( Y1 >>  8 ) ] <<  8 ) ^
                 ( RSb[ (uint8) ( Y0       ) ]       );

    PUT_UINT32( X0, data,  0 );
    PUT_UINT32( X1, data,  4 );
    PUT_UINT32( X2, data,  8 );
    PUT_UINT32( X3, data, 12 );
}

#ifdef TEST

#include <string.h>
#include <stdio.h>

/*
 * those are the standard FIPS 197 test vectors
 */

static unsigned char KEYs[3][32] =
{
    "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F",

    "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F" \
        "\x10\x11\x12\x13\x14\x15\x16\x17",

    "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F" \
        "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F"
};

static unsigned char PT[16] =

    "\x00\x11\x22\x33\x44\x55\x66\x77\x88\x99\xAA\xBB\xCC\xDD\xEE\xFF";

static unsigned char CTs[3][16] =
{
    "\x69\xC4\xE0\xD8\x6A\x7B\x04\x30\xD8\xCD\xB7\x80\x70\xB4\xC5\x5A",
    "\xDD\xA9\x7C\xA4\x86\x4C\xDF\xE0\x6E\xAF\x70\xA0\xEC\x0D\x71\x91",
    "\x8E\xA2\xB7\xCA\x51\x67\x45\xBF\xEA\xFC\x49\x90\x4B\x49\x60\x89"
};

int main( void )
{
    int i;
    struct aes_context ctx;
    unsigned char data[16];

    for( i = 0; i < 3; i++ )
    {
        memcpy( data, PT, 16 );

        aes_set_key( &ctx, KEYs[i], 128 + i * 64 );
        aes_encrypt( &ctx, data );

        printf( "encryption test %d ", i + 1 );

        if( ! memcmp( data, CTs[i], 16 ) )
        {
            printf( "passed\n" );
        }
        else
        {
            printf( "failed\n" );
            return( 1 );
        }
    }

    for( i = 0; i < 3; i++ )
    {
        memcpy( data, CTs[i], 16 );

        aes_set_key( &ctx, KEYs[i], 128 + i * 64 );
        aes_decrypt( &ctx, data );

        printf( "decryption test %d ", i + 1 );

        if( ! memcmp( data, PT, 16 ) )
        {
            printf( "passed\n" );
        }
        else
        {
            printf( "failed\n" );
            return( 1 );
        }
    }

    return( 0 );
}
#endif

hw4.c 用于爆破的程序

#include "aes.c"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int check_ciphertext(uint8 *a, uint8 *b){
	int i = 0;
	for (i = 0; i < 16; i++){
		if (a[i] != b[i])
			return 0; 
	}
	return 1;
}

void hex2uint8(uint8 *input, uint8 *output){
	int i = 0;
	for (i = 0; i < 16; i++){
		output[i] = (input[2*i]<<4) + (input[2*i+1]);
	}
}

int hex2byte(uint8 *dst, uint8 *src) {
	int i = 0;
	for (i = 0; i < 16; i++){ 
		sscanf(src, "%2hhx", dst);
		src += 2;
		dst++;
	}
	return 0;
}

int main(){
    uint8 plaintext[16] = {0x4b, 0x55, 0x4e, 0x50, 0x45, 0x4e, 0x47, 0x5f, 0x48, 0x50, 0x43, 0x5f, 0x41, 0x45, 0x53, 0x21};		//KUNPENG_HPC_AES!
    struct aes_context SK; 
    uint8 buffer[128] = {0};
    uint8 key[16] = {0};
    uint8 input[128] = {0};
    uint8 cipher[16] = {0};
    
	scanf("%s", input);
	memcpy(key, input, 12);
	hex2byte(cipher, input+12);
    
    int i, a, b, c, d;
    char table[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    for (a = 0; a < 62; a++){
    	for (b = 0; b < 62; b++){
			for(c = 0; c < 62; c++){
				for (d = 0; d < 62; d++){
					key[12] = table[a];
					key[13] = table[b];
					key[14] = table[c];
					key[15] = table[d];
					aes_set_key(&SK, key, 128);
					memcpy(buffer, plaintext, 16);
					aes_encrypt(&SK, buffer);
					if (check_ciphertext(buffer, cipher)){
						printf("%c%c%c%c", table[a], table[b], table[c], table[d]);
						exit(0);
					}
				}
			} 
		} 
	}
    return 0;
}

然后呢，虽然给出的dockerfile虽然是x64架构的，但是这个docker只是测试用的。给出的iscpu.txt说明了Architecture: aarch64，是arm64架构。所以要编译成arm的，还好没遇到坑，配好交叉编译的环境后直接成功编译。

然后就是把程序base64，并传进去。

我尝试了几个终端，但是都只传送了4095字节，我以为是python的input函数，缓冲区只有4KB。于是一下午都在研究怎么压文件大小到3KB以下（因为还要base64) 。

最后去厕所的时候，突然想到，会不会是我这边终端的缓冲区的大小是4KB？？？马上用pwntools试了下，成功拿到flag

交互脚本：

import re
from pwn import *
from hashlib import md5
#context.log_level = 'debug'

def calc_md5(r):
    res = re.search(r'Give me xxxx so that bin\(md5\(([a-zA-Z0-9]{10})\+xxxx\)\).startswith\(0\*24\)', r)
    temp = res.group(1)
    print(temp)
    i = 1
    while 1:
        m = md5()
        m.update((temp + str(i)).encode('utf-8'))
        x = m.hexdigest()
        if x[:6] == '000000':
            return str(i).encode()
            break
        i += 1


with open(r'/home/iyzyi/crypto/hw-encode.txt', 'rb')as f:
    text = f.read()


p = remote('139.159.190.149', 10000)
r = p.recvuntil('startswith(0*24)')
result = calc_md5(r.decode())
print(result)
p.sendline(result)
p.sendlineafter('You have 40s to finish this job', text)
print(p.recvline())
print(p.recvline())
print(p.recvline())
print(p.recvline())
print(p.recvline())
print(p.recvline())
print(p.recvline())
print(p.recvline())
print(p.recvline())
print(p.recvline())

crypto

combinelfsr

已知flag的密文，密钥只与R1，R2有关。

R1,R2走了一个联合的lfsr，两个lfsr的反馈值x1和x2不告诉你，只告诉(x1*x2)^(x2^1)的值。

但是化简一下：

x1	x2	(x1*x2)^(x2^1)
0	0	1
0	1	0
1	0	1
1	1	1

所以(x1*x2)^(x2^1)等于0的时候，x1必等于0，x2必等于1.

然后题目说R1和R2小于2的18次方，这个数很小，直接爆破就好啦。

注意加法爆破，千万不要乘法爆破。

from hashlib import sha512
from Crypto.Cipher import AES

def lfsr(R,mask):
        output = (R << 1) & 0xffffff
        i=(R&mask)&0xffffff
        lastbit=0
        while i!=0:
            #print(bin(i)[2:])
            lastbit^=(i&1)
            i=i>>1
        output^=lastbit
        return (output,lastbit)



#with open(r'out', 'rb')as f:
#    tmps = f.read()
#print(tmps)
tmps = b'\xcc\xde\xbd\x9e\xff\xf7f\xd6\xbf\xff\xfb\x97\xa9\xfd\xbe\x7f\x95O\xa7\x96\xff~q\x7f\xfd\xbe\xbe\xff_\xff+w\xed\xbb\xdf\xeeg\xae\xc7\xe7\xbe\xf5\xffo\xbf\x8e\xdd\xc7{\xed\xff\xab\x7f.\x9f\xd9\x7f\xb1\x8f\xfb\xef\xd5\xf9\xfb\xee\xff\xce\xcb\x9f}\xdc\x9b\xa7\xab\xdf\xfb\xe9\xef\x9f\xbf\xbb\xdf\xbd\xcf\xfd\xd7\xbe\xea\x7f\xfe~\x17V\x7f\xaf\xd7\xb7\xeb\xbf\xfe\xcd\x9d\xdf<\xdf\xcb\xfa_\xf8\xef\xfbK\xf6t\xcd\x8fg\xf3{\x7f\xf3T\xd6\xf1o\xde\xe3KWi\xfa\xef7\xfa\xff\xff\xf3\xdc\xfb\xe4\xfa\xff\xf9\xcfwy\xfc\xd9oZ\xac\xe3[/\xff\xef\xff\xffn\xef\xae\xffM\xb7\xfag\xfd\xc5\xff{>\xdfw\x1d\xbd\xf6\xe4\xff\xe7\xd1\xef\x1b\xff\xff]\xff\xba\xd7\xff7\xbfz\xbf~\x7f\xfe\xd7c?\xbf\xf2\xd56\xb7o\xfb\x7f\xf9;\xfe\xb7\xff\x1e\xb0\xef\xfb\xfd\xa4\xff\xbf\xff#\x12\x7f7\x7f\xde\xdf{\xbf\x85\xf8\xfdc\xeb\x9f?\xbf\xfb\xa7\\\xaf\xa6\xf1\x9f\xff\xdc\xff\xeb\xa7\xfe\xff\xdfO\xbe\xff\xd7\xfc\xf9\xddWl\xff\xbb\x98\xbf\xecz\xb6\xbfw\x7f^\xe4\x7f\xb7\xa9\xef\xf6\xef\xff\xcb\xffj\xff\xcfo\xf9\x9e\xdf\xbf\xbf\xf0\xef\xe6\xdb\xfc\xe2\xe5i\xf7o]\xde\xbe}y\xe7w\xcb\xff\xbc\xf57\xf4N\xf3\xef=\xb7w\xed\xff\xfd\xf3^\xf0v\xff\xb3\x8b\x96\xea\xff?\xf8\xf3\x9e\xeb_\xdb\x7f\xdf[\xfb\xd7\xae\xb9=\x7f\x1f\xef\xbf\xd5\xfbx\xdf\xf5}\x96\xfc{\xdf\xff\xaf\xff\xee\x7f\x96\xfb\xff\xe9\xff\xef\xde\xbfj\xff\xffo\xffw\xf3\xf1\xbb?\xe7\xe7\xdf\xff\x7f\xbf\xa6\xbf\x7f\xb7\xbf?\xffw\xf7\xca\x88\xfe\xfe\xfd\xff\xe3\xe3\xfe\xfdu\xfb\x7f\x99\xbf\xef\xf3\xdf\xff\xd7\xf9\xbe\xcb\xef/o\xde\xed\xect\xfb\xbe\xff\xdb\xfd\xbf\xdfn\xf1\xff\x8f\x7f7\xbe}\xc6\x1f\xef\xfd\xe7_\xbf\xf5\xff\xfe\xed\xee{\xf2\xfb\xff\xff\x0e\xde\xff\x9b[\xb7\xc5\xbf\xff\xe6w\x7f\xdf\xff;\xadi>\xff\xf7\xfd\xf2\xb7\xdc\xbb\xdf\xfe\xfb\xde\xab~\xd7\xf7\x15\xde\xfb/\xbf=\xf56\xff\xde\xefn\xb2\xff\xed\xfd\xfe\xfe\xbf\x7fo\xfe\xfd\xef\x93\xfdo\xed\xdf\xef\xe3\xde\xff\xbf\xea}\xb5[z\xfb\xff\xc5\xef}\xdf\x7fe\x7f\x1e\xdb\xd7\xfdb\xf5\xfa\xfa\xb3\xcf\xf6\xee\x9e\xbf\xfcn\xcf\xeb\xcfX}~_\xfd\x8e\xbf_\xf9\xab\xfe\xdb\xf1\xe5\xac\xfcwo_?\x7f\xd3\xfb\xf7\xd9\xfe\xff\xef}\xb6\xdf\xdbu\x7fY\xdf\xf7\xde\xbf_\xff\xed\xfa\xf5\xdf\x9f\xdfi\xd9\xbe}\xf7\xa5\xbf\xd7\xff\xf7\xf78\xfd~\xa8\xef\xbe}\xff\xa7g\xd4\xed\xbf\xf1\xf7\xfb\xbf\xef\xees\xff\xf6\xf9o\xbf\xff\xe3\xfd\xff_go\xef\xbe\xd7\x97\x7f\xfe\xff\xf7\xbf\x8b\xfb~\xff\xfb\x0b\xe7\xfd\xd7{\xbf\x9d]\xd5^\xbe}s\xee\x1f9\x8a\xea\x9d\xff\xef\xfd\xdb\xf7\xbf\xc7\xf3\xd2\xbf:{\xcfS\xf6\xcf\xb3o\xff\xf3\x7f\xbf\xfb\xbd\x7f\x7fn_\x9f\xff\xec\xcf\xf2\xff\xbd|\xf9\xe3\x96\xa5\xfd\x8b\xbdko\xe9\xd57\xed\xbb\xff\xdf\xde\xff\xfe\xff\xef;z\xbes\xfb\xe9\xce\xbc\x9f\xb9\x7f?|\x18Q\xeb\xfb\xf7\xdf\xfa\xfeu\xda\xfd\xff\xbf\xffw\xbb\xfe\xefM\xefn\xd2u3\xdf\xcb\xcc\xb7\x8f\x9a\xfe\x8f\x9d\xae\xdd\xbb\xb6\x7f\xe6\xcf\x7f\xaf\xb2\xff?\xff\x7f\xfd\x9f\xb7\xfb\x9ew\xdf\xd8\xb3\xff\xef\x9e\xf6{\xdak\xfb\xe9\xf7\xdd\xdf\xc7\xff\xdf\xe7s\xfd\x8b\x9e\xfe\xee\xe7\xf1\x9e9\xbf?\xf5\xed\xeey:\xb6\xdf\x9ft\xde\x95\xb7\xbf~\xed\xff\xff\xdf\xd3\xf7z\xf3\xca\xfe\xd7\xaf\xbf\x7f\xff\xc9\xd7\xff\xfb\x99~\xff}\xff\xe7\x7f5\xcd\xff\xd7\xddz\xdf\xf2\xfb\xa3\x7f\xbb~\xf7\xf7\x80\xde\xee\xcd\x1e\xbb\xfd\xcf?\xcf\xff\xaf\xbf\xbf\xdf\xb7\x7f\xf9\xff~\xff\xdf\xef\x8dz\x8f\xbb\x7f\xf9/\xb7\xbf\xd6/\xe78\xef_\xfe?\xe9\xb3\x98\xff\xef\x7f\xa7\xf3_\x9e\xf7W\xff\xef\xff\xffn\xdf\xff\xdf\xe1u\xd2\xbd\xff\xa4\xd3Y\xf0\xfc?\xee\xfd\x7f\xef\xffE{\xbf\xf6\xf2\xbf\xf73W\xbd\xea\xcf\x8b\xff\xf93\xeb\xcd\xb5\x93\xff\xbe\xffs\x8d\xf7\xf5\xf6\xfd=[\xfbq\xff\xfc\xbd\xff\xbc\xad\xa7\xf5qW\xc8\xcd}\xf7~~[\xcd\xfa\xf7'

outs = []
for i in range(len(tmps)-1, -1, -1):
    res = bin(tmps[i])[2:].zfill(8)[::-1]
    outs += res
outs = [int(outs[i]) for i in range(len(outs))]
outs = outs[::-1]

mask1 = 0x30517
for r1 in range(1, 2**18):
    temp = r1
    right = True
    for i in range(len(outs)):
        temp, x1 = lfsr(temp, mask1)
        if outs[i] == 0:
            if x1 != 0:
                right = False
                break
    if right:
        print(r1)

print()

mask2 = 0x25b74
for r2 in range(1, 2**18):
    temp = r2
    right = True
    for i in range(len(outs)):
        temp, x2 = lfsr(temp, mask2)
        if outs[i] == 0:
            if x2 != 1:
                right = False
                break
    if right:
        print(r2)

爆出R1和R2后，解密flag:

from hashlib import sha512
from Crypto.Cipher import AES
from binascii import *


R1 = 13706
R2 = 90307
flag = unhexlify('b5bc56c17db4a7d898ce63652d3656572e4f5b6757fccef8d8d3a32dc60bfc972d40f061f3a7154f7975d5126b052dad')
key = sha512(str(R1).encode()+str(R2).encode()).digest()[:16]
aes = AES.new(key,AES.MODE_ECB)
flag = aes.decrypt(flag)
print(flag)

reverse

mips

就是个迷宫题，最近 ida7.5泄露了，所以这题难度直线下降。

走三次迷宫，从3开始走，走到4.

1 1 1 1 1 0 3 0 1 0 0 0 0 0 0 
1 1 1 1 1 0 1 0 1 0 0 0 0 0 0 
1 1 1 1 1 0 1 0 1 0 0 0 0 0 0 
1 1 1 1 1 0 1 0 1 1 1 1 1 0 0 
1 1 1 1 1 0 1 0 0 0 0 0 1 0 0 
1 1 1 1 1 0 1 0 0 0 0 0 1 0 0 
1 1 1 1 1 0 1 0 0 0 0 0 1 1 0 
1 1 1 1 1 0 1 1 1 1 1 1 1 1 0 
1 1 1 1 1 0 0 0 0 0 0 0 0 4 0 
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
1 1 0 3 0 1 1 1 1 0 0 0 0 0 0 
1 1 0 1 0 0 0 0 1 0 0 0 0 0 0 
1 1 0 1 0 0 0 0 1 0 0 0 0 0 0 
1 1 0 1 1 0 0 0 1 1 1 1 1 0 0 
1 1 0 1 1 0 0 0 0 0 0 0 1 0 0 
1 1 0 1 1 0 0 0 0 0 0 0 1 0 0 
1 1 0 1 1 0 0 0 0 0 1 1 1 1 0 
1 1 0 1 1 0 0 0 0 0 1 0 0 1 0 
1 1 0 1 1 0 0 0 0 0 1 0 0 0 0
1 1 0 1 1 1 1 1 1 0 1 0 1 1 0 
1 1 0 1 1 1 1 1 1 1 1 1 1 1 0
1 1 0 0 0 0 0 0 0 0 0 0 0 4 0
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 3 1 1 0 0 0 0 0 0 0 0 0 0 0
0 0 0 1 0 1 1 1 0 0 0 0 0 0 0
0 0 0 1 1 1 0 1 0 0 0 0 0 0 0
0 0 0 0 1 0 0 1 0 0 0 0 0 0 0
0 1 1 0 1 0 0 1 0 0 0 0 0 0 0
0 0 1 1 1 0 0 1 0 0 0 0 0 0 0
0 0 0 0 0 0 0 1 0 0 0 0 0 0 0
0 0 0 0 0 0 0 1 1 1 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 1 1 1 1 0
0 0 0 0 0 0 0 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0 0 0 0 0 4 0

table = [1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 3, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 3, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0]
print(len(table))
for loop in range(3):
    for i in range(15):
        for j in range(15):
            print(table[loop * 225 + 15 * i + j],end=' ')
        print()
    print()

# sssssssddddddds
# ssssssssssdddddddddds 此段多解哦
# ddssddwddssssssdddssssdddss

这题队友做的，我赛后补的题，程序也不好运行起来，也不知道flag对不对，不过原理就是这样。

pypy

python3.8.5写的pygame，然后pyinstaller打的包。

直接解包是失败的。读了下pyinstxtractor.py的源码，原来是没找到魔数。

pyinstaller打包的程序，在文件末尾，有b'MEI\014\013\012\013\016'的魔数，对于pyinstaller 2.0，这个魔数在程序末尾倒数24字节开始，对于pyinstaller 2.1+，这个魔数在程序末尾倒数24+64字节开始。

但是本题给出的程序，这个魔数在程序末尾倒数2000+字节。

大胆试了下删掉后面的数据，使得魔数在程序末尾倒数24+64字节。

然后就成功解包了。

然后就是pyc转py。首先修复下pyc头，然后转。

混淆了，简单改下变量名，有的变量对于解题不相干，我就没改。

# uncompyle6 version 3.7.4
# Python bytecode 3.8 (3413)
# Decompiled from: Python 3.7.1 (v3.7.1:260ec2c36a, Oct 20 2018, 14:57:15) [MSC v.1915 64 bit (AMD64)]
# Embedded file name: main.py
# Compiled at: 2020-12-22 18:08:11
# Size of source mod 2**32: 11 bytes
import random, codecs, sys, time, pygame
from pygame.locals import *
from collections import deque
SCREEN_WIDTH = 600
SCREEN_HEIGHT = 480
SIZE = 20
LINE_WIDTH = 1
flag = 'flag{this is a fake flag}'
SCOPE_X = (0, SCREEN_WIDTH // SIZE - 1)
SCOPE_Y = (2, SCREEN_HEIGHT // SIZE - 1)
FOOD_STYLE_LIST = [(10, (255, 100, 100)), (20, (100, 255, 100)), (30, (100, 100, 255))]
LIGHT = (100, 100, 100)
DARK = (200, 200, 200)
BLACK = (0, 0, 0)
RED = (200, 30, 30)
BGCOLOR = (40, 40, 60)

def print_text(OO0O0OOO0OO0OOOOO, OOO00O0OOO0OO0O00, O0OOOO00000O0OOOO, OO00OO0O0OOOOO000, OO0O00O00O000OOO0, fcolor=(255, 255, 255)):
    O0O0OO0O00O0OO0OO = OOO00O0OOO0OO0O00.render(OO0O00O00O000OOO0, True, fcolor)
    OO0O0OOO0OO0OOOOO.blit(O0O0OO0O00O0OO0OO, (O0OOOO00000O0OOOO, OO00OO0O0OOOOO000))


def init_snake():
    snake_body = deque()
    snake_body.append((2, SCOPE_Y[0]))
    snake_body.append((1, SCOPE_Y[0]))
    snake_body.append((0, SCOPE_Y[0]))
    return snake_body


def create_food(snake_body):
    random1 = random.randint(SCOPE_X[0], SCOPE_X[1])
    random2 = random.randint(SCOPE_Y[0], SCOPE_Y[1])
    while (random1, random2) in snake_body:
        random1 = random.randint(SCOPE_X[0], SCOPE_X[1])
        random2 = random.randint(SCOPE_Y[0], SCOPE_Y[1])
    return (random1, random2)


def get_food_style():
    return FOOD_STYLE_LIST[random.randint(0, 2)]


DEFAULT_KEY = 'Yó\x02Ã%\x9a\x820\x0b»%\x7f~;ÒÜ'

def rc4(buffer, key=DEFAULT_KEY, skip=1024):
    j = 0
    s = bytearray([i for i in range(256)])
    j = 0
    for i in range(256):
        j = (j + s[i] + ord(key[(i % len(key))])) % 256
        temp = s[i]
        O000O0OO00O00000O = s[j]
        s[i] = s[j]
        s[j] = temp
    else:
        j = 0
        k = 0
        res = []
        if skip > 0:
            for i in range(skip):
                j = (j + 1) % 256
                k = (k + s[j]) % 256
                s[j], s[k] = s[k], s[j]

        for data in buffer:
            j = (j + 1) % 256
            k = (k + s[j]) % 256
            s[j], s[k] = s[k], s[j]
            t = s[((s[j] + s[k]) % 256)]
            res.append(chr(ord(data) ^ t))
        else:
            return ''.join(res)


def check_flag(flag):
    ciphertext = rc4(flag)
    if ciphertext.encode('utf-8').hex() == '275b39c381c28b701ac3972338456022c2ba06c3b04f5501471c47c38ac380c29b72c3b5c38a7ec2a5c2a0':
        return 'YOU WIN'
    return 'YOU LOSE'


def main():
    pygame.init()
    pygame_display = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))
    pygame.display.set_caption('贪吃蛇')
    pygame_font = pygame.font.SysFont('SimHei', 24)
    pygame_font2 = pygame.font.Font(None, 72)
    OOOO00OO0O0O00000, OO00O00OOOOO000O0 = pygame_font2.size('GAME OVER')
    bool1 = True
    snake_body = init_snake()
    snake_body = create_food(snake_body)
    food_style = get_food_style()
    O00OOOO00O0O0OO0O = (1, 0)
    O0OO0000O000OOO00 = True
    OO000OOO0O000O00O = False
    score = 0
    OOO0OOOOOO0O0OOO0 = 0.5
    OOO00OOO0O0O00OOO = OOO0OOOOOO0O0OOO0
    time1 = None
    OO000OOOOO00O00OO = False
    for pygame_event_get in pygame.event.get():
        if pygame_event_get.type == QUIT:
            sys.exit()
        elif pygame_event_get.type == KEYDOWN:
            if pygame_event_get.key == K_RETURN:
                if O0OO0000O000OOO00:
                    OO000OOO0O000O00O = True
                    O0OO0000O000OOO00 = False
                    bool1 = True
                    snake_body = init_snake()
                    snake_body = create_food(snake_body)
                    food_style = get_food_style()
                    O00OOOO00O0O0OO0O = (1, 0)
                    score = 0
                    time1 = time.time()
        elif pygame_event_get.key == K_SPACE:
            if not O0OO0000O000OOO00:
                OO000OOOOO00O00OO = not OO000OOOOO00O00OO
        elif pygame_event_get.key in (K_w, K_UP):
            if bool1:
                O00OOOO00O0O0OO0O = O00OOOO00O0O0OO0O[1] or (0, -1)
                bool1 = False
        elif pygame_event_get.key in (K_s, K_DOWN):
            if bool1:
                O00OOOO00O0O0OO0O = O00OOOO00O0O0OO0O[1] or (0, 1)
                bool1 = False
        elif pygame_event_get.key in (K_a, K_LEFT):
            if bool1:
                if not O00OOOO00O0O0OO0O[0]:
                    O00OOOO00O0O0OO0O = (-1, 0)
                    bool1 = False
                elif pygame_event_get.key in (K_d, K_RIGHT):
                    if bool1:
                        if not O00OOOO00O0O0OO0O[0]:
                            O00OOOO00O0O0OO0O = (1, 0)
                            bool1 = False
        else:
            pygame_display.fill(BGCOLOR)
            for O00O0OOOO0OO0000O in range(SIZE, SCREEN_WIDTH, SIZE):
                pygame.draw.line(pygame_display, BLACK, (O00O0OOOO0OO0000O, SCOPE_Y[0] * SIZE), (O00O0OOOO0OO0000O, SCREEN_HEIGHT), LINE_WIDTH)
            else:
                for OO0000O0000OO0000 in range(SCOPE_Y[0] * SIZE, SCREEN_HEIGHT, SIZE):
                    pygame.draw.line(pygame_display, BLACK, (0, OO0000O0000OO0000), (SCREEN_WIDTH, OO0000O0000OO0000), LINE_WIDTH)
                else:
                    O0O0O0O00OOO0OOO0 = O0OO0000O000OOO00 or time.time()

            if O0O0O0O00OOO0OOO0 - time1 > OOO00OOO0O0O00OOO and not OO000OOOOO00O00OO:
                bool1 = True
                time1 = O0O0O0O00OOO0OOO0
                O0O00OO0OO000OOOO = (snake_body[0][0] + O00OOOO00O0O0OO0O[0], snake_body[0][1] + O00OOOO00O0O0OO0O[1])
                if O0O00OO0OO000OOOO == snake_body:
                    snake_body.appendleft(O0O00OO0OO000OOOO)
                    score += food_style[0]
                    OOO00OOO0O0O00OOO = OOO0OOOOOO0O0OOO0 - 0.03 * (score // 100)
                    snake_body = create_food(snake_body)
                    food_style = get_food_style()
                else:
                    if SCOPE_X[0] <= O0O00OO0OO000OOOO[0] <= SCOPE_X[1]:
                        if SCOPE_Y[0] <= O0O00OO0OO000OOOO[1] <= SCOPE_Y[1]:
                            if O0O00OO0OO000OOOO not in snake_body:
                                snake_body.appendleft(O0O00OO0OO000OOOO)
                                snake_body.pop()
                            else:
                                O0OO0000O000OOO00 = True
                    if not O0OO0000O000OOO00:
                        pygame.draw.rect(pygame_display, food_style[1], (snake_body[0] * SIZE, snake_body[1] * SIZE, SIZE, SIZE), 0)
                for OO00OOO00OOO00000 in snake_body:
                    pygame.draw.rect(pygame_display, DARK, (OO00OOO00OOO00000[0] * SIZE + LINE_WIDTH, OO00OOO00OOO00000[1] * SIZE + LINE_WIDTH, SIZE - LINE_WIDTH * 2, SIZE - LINE_WIDTH * 2), 0)
                else:
                    print_text(pygame_display, pygame_font, 30, 7, f"speed: {score // 100}")
                    print_text(pygame_display, pygame_font, 450, 7, f"score: {score}")
                    if score >= 5192296858534827628530496329220096:
                        _flag = flag
                        print_text(pygame_display, pygame_font2, (SCREEN_WIDTH - OOOO00OO0O0O00000) // 2, (SCREEN_HEIGHT - OO00O00OOOOO000O0) // 2, check_flag(_flag), RED)
                    if O0OO0000O000OOO00:
                        if OO000OOO0O000O00O:
                            print_text(pygame_display, pygame_font2, (SCREEN_WIDTH - OOOO00OO0O0O00000) // 2, (SCREEN_HEIGHT - OO00O00OOOOO000O0) // 2, 'GAME OVER', RED)
                    pygame.display.update()


if __name__ == '__main__':
    main()
# okay decompiling main.pyc

看着复杂，其实就是个变种rc4。

已知密文和密钥，虽然是变种的rc4，但仍然是序列密码，所以再走一遍加密函数就好啦。

直接把加密函数复制过来就行。

from binascii import *
import struct

DEFAULT_KEY = 'Yó\x02Ã%\x9a\x820\x0b»%\x7f~;ÒÜ'

def rc4(O0O0O0000O0OOOO0O, key=DEFAULT_KEY, skip=1024):
    O00OOOOOOO00OO00O = 0
    OO0OOOO0000OO00OO = bytearray([OO00OOOO0OOOOO00O for OO00OOOO0OOOOO00O in range(256)])
    O00OOOOOOO00OO00O = 0
    for OOOO000OOO00O000O in range(256):
        O00OOOOOOO00OO00O = (O00OOOOOOO00OO00O + OO0OOOO0000OO00OO[OOOO000OOO00O000O] + ord(key[(OOOO000OOO00O000O % len(key))])) % 256
        OO000O0O0OOOOO0OO = OO0OOOO0000OO00OO[OOOO000OOO00O000O]
        O000O0OO00O00000O = OO0OOOO0000OO00OO[O00OOOOOOO00OO00O]
        OO0OOOO0000OO00OO[OOOO000OOO00O000O] = OO0OOOO0000OO00OO[O00OOOOOOO00OO00O]
        OO0OOOO0000OO00OO[O00OOOOOOO00OO00O] = OO000O0O0OOOOO0OO
    else:
        O00OOOOOOO00OO00O = 0
        O0O0OO0OO00OOOOO0 = 0
        OO0OOO000000OO0O0 = []
        if skip > 0:
            for OOOO000OOO00O000O in range(skip):
                O00OOOOOOO00OO00O = (O00OOOOOOO00OO00O + 1) % 256
                O0O0OO0OO00OOOOO0 = (O0O0OO0OO00OOOOO0 + OO0OOOO0000OO00OO[O00OOOOOOO00OO00O]) % 256
                OO0OOOO0000OO00OO[O00OOOOOOO00OO00O], OO0OOOO0000OO00OO[O0O0OO0OO00OOOOO0] = OO0OOOO0000OO00OO[O0O0OO0OO00OOOOO0], OO0OOOO0000OO00OO[O00OOOOOOO00OO00O]

        for O0000O0OOO000OO0O in O0O0O0000O0OOOO0O:
            O00OOOOOOO00OO00O = (O00OOOOOOO00OO00O + 1) % 256
            O0O0OO0OO00OOOOO0 = (O0O0OO0OO00OOOOO0 + OO0OOOO0000OO00OO[O00OOOOOOO00OO00O]) % 256
            OO0OOOO0000OO00OO[O00OOOOOOO00OO00O], OO0OOOO0000OO00OO[O0O0OO0OO00OOOOO0] = OO0OOOO0000OO00OO[O0O0OO0OO00OOOOO0], OO0OOOO0000OO00OO[O00OOOOOOO00OO00O]
            O0O0OOOO0OOOOO0OO = OO0OOOO0000OO00OO[((OO0OOOO0000OO00OO[O00OOOOOOO00OO00O] + OO0OOOO0000OO00OO[O0O0OO0OO00OOOOO0]) % 256)]
            OO0OOO000000OO0O0.append(chr(ord(O0000O0OOO000OO0O) ^ O0O0OOOO0OOOOO0OO))
        else:
            return ''.join(OO0OOO000000OO0O0)


ciphertext = unhexlify('275b39c381c28b701ac3972338456022c2ba06c3b04f5501471c47c38ac380c29b72c3b5c38a7ec2a5c2a0').decode()
#key = 'Yó\x02Ã%\x9a\x820\x0b»%\x7f~;ÒÜ'
#key = b'\x59\xc3\xb3\x02\xc3\x83\x25\xc2\x9a\xc2\x82\x30\x0b\xc2\xbb\x25\x7f\x7e\x3b\xc3\x92\xc3\x9c\x69\x00\x04'

r = rc4(ciphertext)
print(r)

但是，有个大坑，编码问题。

DEFAULT_KEY是Yó\x02Ã%\x9a\x820\x0b»%\x7f~;ÒÜ，这个是十六字节，但是转换成字节流是23字节。我一开始把加密函数改了一点，改成了字节流参与运算，一直求不出flag。直到我直接把加密函数复制过来，一点改动都没有，完全是题目的逻辑，就拿到flag了。