2022祥云杯CTF babyparser

1mmortal 看雪学苑 2022-12-18

收录于合集 #“雪花”创作激励计划 233个

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看雪论坛作者ID：1mmortal

这道题是比赛结束前3小时放出来的，最后是0解。我有理由怀疑这是一道防ak题。

原题附件需要glibc2.34，但我的kali版本不够高，所以我patchelf成自编译的2.34，也因此搞丢了原题附件，现在上传的是patchelf以后的版本，如果有需要可以自己patch回去。

一

比赛时的逆向

比赛时候打开一看啊，发现这个程序用了ollvm的deflat来进行混淆，而且仔细一看是个全混淆，所有能混淆的地方它都混淆了。还好之前有所准备，拿起了之前备好的脚本准备一把梭。梭完一看发现失败了，原来是这个ollvm改良过，出题人修改了deflat的llvm pass ，分发逻辑增加了一步。其中真实块的样子大概是这样的：

这时候我以为出题人把打乱的函数都用上图中类似的call rax 间接调用来实现。此时我心态平和，我以为还剩三小时放出来的题必不会很难，于是想尝试修改上面那个基于angr的deflat脚本。我低估了其中的难度，对于angr本身也不熟悉的我根本改不来。所以最后尝试动调加手动patch binary。但是只是尝试了一会我就发现这个做不到，因为量太大了。因此最后决定这题先放弃，跑去做别的了。

二

赛后复盘

去混淆

赛后当然还是想把这道题deflat出来，于是在之前的基础上学习了angr的用法，折腾了几天，发现angr作为符号执行的工具对于这种去混淆的处理其实并不是很合适。因为deflat部分的处理本质上是在模拟执行程序，并且记录真实的控制流，而这部分并不是angr所擅长的。那么谁更合适呢？当然是模拟执行的神器unicorn！

转头去尝试用unicorn完成deflat后，这题终于也走上了正轨。找了已有的unicorn deflat脚本，并在此基础上进行更改，写出了一个deflat脚本：

#coding=utf-8 import collectionsimport angr import am_graphfrom util import * # from keystone import *from unicorn import *from unicorn.x86_const import *from capstone import *from capstone.x86 import * obfus = [0x405DA0, 0x417610, 0x4149D0]  def reg_ctou(regname:str):    # This function covert capstone reg name to unicorn reg const.    # https://github.com/unicorn-engine/unicorn/blob/master/bindings/python/unicorn/x86_const.py    mp =  { 'INVALID' : 0,  'AH' : 1,  'AL' : 2,  'AX' : 3,  'BH' : 4,  'BL' : 5,  'BP' : 6,  'BPL' : 7,  'BX' : 8,  'CH' : 9,  'CL' : 10,  'CS' : 11,  'CX' : 12,  'DH' : 13,  'DI' : 14,  'DIL' : 15,  'DL' : 16,  'DS' : 17,  'DX' : 18,  'EAX' : 19,  'EBP' : 20,  'EBX' : 21,  'ECX' : 22,  'EDI' : 23,  'EDX' : 24,  'EFLAGS' : 25,  'EIP' : 26,  'ES' : 28,  'ESI' : 29,  'ESP' : 30,  'FPSW' : 31,  'FS' : 32,  'GS' : 33,  'IP' : 34,  'RAX' : 35,  'RBP' : 36,  'RBX' : 37,  'RCX' : 38,  'RDI' : 39,  'RDX' : 40,  'RIP' : 41,  'RSI' : 43,  'RSP' : 44,  'SI' : 45,  'SIL' : 46,  'SP' : 47,  'SPL' : 48,  'SS' : 49,  'CR0' : 50,  'CR1' : 51,  'CR2' : 52,  'CR3' : 53,  'CR4' : 54,  'CR8' : 58,  'DR0' : 66,  'DR1' : 67,  'DR2' : 68,  'DR3' : 69,  'DR4' : 70,  'DR5' : 71,  'DR6' : 72,  'DR7' : 73,  'FP0' : 82,  'FP1' : 83,  'FP2' : 84,  'FP3' : 85,  'FP4' : 86,  'FP5' : 87,  'FP6' : 88,  'FP7' : 89,  'K0' : 90,  'K1' : 91,  'K2' : 92,  'K3' : 93,  'K4' : 94,  'K5' : 95,  'K6' : 96,  'K7' : 97,  'MM0' : 98,  'MM1' : 99,  'MM2' : 100,  'MM3' : 101,  'MM4' : 102,  'MM5' : 103,  'MM6' : 104,  'MM7' : 105,  'R8' : 106,  'R9' : 107,  'R10' : 108,  'R11' : 109,  'R12' : 110,  'R13' : 111,  'R14' : 112,  'R15' : 113,  'ST0' : 114,  'ST1' : 115,  'ST2' : 116,  'ST3' : 117,  'ST4' : 118,  'ST5' : 119,  'ST6' : 120,  'ST7' : 121,  'XMM0' : 122,  'XMM1' : 123,  'XMM2' : 124,  'XMM3' : 125,  'XMM4' : 126,  'XMM5' : 127,  'XMM6' : 128,  'XMM7' : 129,  'XMM8' : 130,  'XMM9' : 131,  'XMM10' : 132,  'XMM11' : 133,  'XMM12' : 134,  'XMM13' : 135,  'XMM14' : 136,  'XMM15' : 137,  'XMM16' : 138,  'XMM17' : 139,  'XMM18' : 140,  'XMM19' : 141,  'XMM20' : 142,  'XMM21' : 143,  'XMM22' : 144,  'XMM23' : 145,  'XMM24' : 146,  'XMM25' : 147,  'XMM26' : 148,  'XMM27' : 149,  'XMM28' : 150,  'XMM29' : 151,  'XMM30' : 152,  'XMM31' : 153,  'YMM0' : 154,  'YMM1' : 155,  'YMM2' : 156,  'YMM3' : 157,  'YMM4' : 158,  'YMM5' : 159,  'YMM6' : 160,  'YMM7' : 161,  'YMM8' : 162,  'YMM9' : 163,  'YMM10' : 164,  'YMM11' : 165,  'YMM12' : 166,  'YMM13' : 167,  'YMM14' : 168,  'YMM15' : 169,  'YMM16' : 170,  'YMM17' : 171,  'YMM18' : 172,  'YMM19' : 173,  'YMM20' : 174,  'YMM21' : 175,  'YMM22' : 176,  'YMM23' : 177,  'YMM24' : 178,  'YMM25' : 179,  'YMM26' : 180,  'YMM27' : 181,  'YMM28' : 182,  'YMM29' : 183,  'YMM30' : 184,  'YMM31' : 185,  'ZMM0' : 186,  'ZMM1' : 187,  'ZMM2' : 188,  'ZMM3' : 189,  'ZMM4' : 190,  'ZMM5' : 191,  'ZMM6' : 192,  'ZMM7' : 193,  'ZMM8' : 194,  'ZMM9' : 195,  'ZMM10' : 196,  'ZMM11' : 197,  'ZMM12' : 198,  'ZMM13' : 199,  'ZMM14' : 200,  'ZMM15' : 201,  'ZMM16' : 202,  'ZMM17' : 203,  'ZMM18' : 204,  'ZMM19' : 205,  'ZMM20' : 206,  'ZMM21' : 207,  'ZMM22' : 208,  'ZMM23' : 209,  'ZMM24' : 210,  'ZMM25' : 211,  'ZMM26' : 212,  'ZMM27' : 213,  'ZMM28' : 214,  'ZMM29' : 215,  'ZMM30' : 216,  'ZMM31' : 217,  'R8B' : 218,  'R9B' : 219,  'R10B' : 220,  'R11B' : 221,  'R12B' : 222,  'R13B' : 223,  'R14B' : 224,  'R15B' : 225,  'R8D' : 226,  'R9D' : 227,  'R10D' : 228,  'R11D' : 229,  'R12D' : 230,  'R13D' : 231,  'R14D' : 232,  'R15D' : 233,  'R8W' : 234,  'R9W' : 235,  'R10W' : 236,  'R11W' : 237,  'R12W' : 238,  'R13W' : 239,  'R14W' : 240,  'R15W' : 241,  'IDTR' : 242,  'GDTR' : 243,  'LDTR' : 244,  'TR' : 245,  'FPCW' : 246,  'FPTAG' : 247,  'MSR' : 248,  'MXCSR' : 249,  'FS_BASE' : 250,  'GS_BASE' : 251,  'FLAGS' : 252,  'RFLAGS' : 253,  'FIP' : 254,  'FCS' : 255,  'FDP' : 256,  'FDS' : 257,  'FOP' : 258,  'ENDING' : 259,  }    regname = regname.upper()    return mp[regname]  def get_context(): # record all X86/64 regs     global mu    return mu.context_save() def set_context(context:bytes):    global mu    if context == None :        return    else:        mu.context_restore(context)    return # callback for memory exceptiondef hook_mem_access(uc,type,address,size,value,userdata):    pc = uc.reg_read(UC_X86_REG_RIP)    print ('pc:%x type:%d addr:%x size:%x' % (pc,type,address,size)) def hook_code(uc, address, size, user_data):     global base    global is_success    global list_trace    global relevants    global next_real_block_addr    global block_start_addr    global branch_control    global instrs_size    global memset_count    global nop_instruc    instrs_size = size    if is_success:        uc.emu_stop()        return     # if address > end:     #     uc.emu_stop()    #     return     for ins in md.disasm(bin[address-base:address -base + size], address-base):        #print(">>> Tracing instruction at 0x%x, instruction size = 0x%x" % (address, size))        #print(">>> 0x%x:\t%s\t%s" % (ins.address, ins.mnemonic, ins.op_str))         #  bfs 的visit array  防止陷入循环        if address in relevants:            if address in list_trace:                print("sssssss")                uc.emu_stop()            else:                list_trace[address] = 1         # 找到了下一个块        if address in relevants and address != block_start_addr:            is_success = True            next_real_block_addr = address            #print 'find:%x' % address            uc.emu_stop()            return         #是否跳过指令        flag_pass = False        if ins.mnemonic.startswith("call") :            if(ins.op_str  == '0x2090' and memset_count < 2):  # hook memset twice                memset_count += 1                ptr = uc.reg_read(UC_X86_REG_RDI)                val = uc.reg_read(UC_X86_REG_ESI).to_bytes(1,'little')                siz = uc.reg_read(UC_X86_REG_EDX)                uc.mem_write(ptr,val*siz)                flag_pass = True             elif(ins.op_str not in ('rax','rbx','rcx','rdx','rsi','rdi','r8','r9','r10','r11','r12','r13','r14','r15') ):                flag_pass = True            elif(ins.op_str in ('rax','rbx','rcx','rdx','rsi','rdi','r8','r9','r10','r11','r12','r13','r14','r15')):                func = uc.reg_read(reg_ctou(ins.op_str))                if func in obfus:                    nop_instruc.add((address,size))                else:                    flag_pass = True         # 用于跳过指令        if flag_pass:            uc.reg_write(UC_X86_REG_RIP, address + size)            return              # 结束块单独处理        if ins.id == X86_INS_RET :            if relevants[block_start_addr] in retn_nodes:                # uc.reg_write(UC_X86_REG_RIP, 0) # 必须注释掉  https://github.com/unicorn-engine/unicorn/issues/1133                is_success = False                print ("ret ins in {}".format(hex(address)))                uc.emu_stop()                return            else: # in obfus function                pass          #ollvm branch        if ins.mnemonic.startswith('cmov'):            #print("csel 0x%x:\t%s\t%s" %(ins.address, ins.mnemonic, ins.op_str))            regs = [reg_ctou(x) for x in ins.op_str.split(', ')]            assert len(regs) == 2            v1 = uc.reg_read(regs[0])            v2 = uc.reg_read(regs[1])            if branch_control == 1:                uc.reg_write(regs[0], v1)            else:                uc.reg_write(regs[0], v2)            uc.reg_write(UC_X86_REG_RIP, address + size)  def find_path(start_addr,branch = None, from_error = False):    global bin    global base    global mu    global list_trace    global block_start_addr    global next_real_block_addr    global is_success    global branch_control    try:        list_trace = {}        if from_error == False:            block_start_addr = start_addr        is_success = False        next_real_block_addr = 0        branch_control = branch        mu.emu_start(start_addr, start_addr+0x10000) # unitl 参数不重要 因为hookcode会断住     except UcError as e:        pc = mu.reg_read(UC_X86_REG_RIP)        if pc != 0:            # 模拟执行碰到和恢复控制流无关的问题，就略过该指令继续运行            # 是一个递归，block不大的情况下应该不会递归爆炸            print(" pc:%x  block_start_addr:%x" % (pc,block_start_addr))            return find_path(pc + instrs_size, branch, from_error=True)        else:            print("ERROR: %s  pc:%x  block_start_addr:%x" % (e,pc,block_start_addr))     if is_success:        return next_real_block_addr    return None  def fix(bin:bytearray,flow:dict,nop_nodes:list, patch_instrs :dict):    ori_len = len(bin)    # patch irrelevant blocks    for nop_node in nop_nodes:        fill_nop(bin, nop_node.addr-base,                 nop_node.size, project.arch)    for a in nop_instruc:        fill_nop(bin, a[0]-base, a[1], project.arch)    # remove unnecessary control flows    for parent, childs in flow.items():        parent = relevants[parent]        if len(childs) == 1:            parent_block = project.factory.block(parent.addr, size=parent.size)            last_instr = parent_block.capstone.insns[-1]            file_offset = last_instr.address - base            # patch the last instruction to jmp             if(parent.addr + parent.size == childs[0] and last_instr.op_str != hex(the_last_jmp_block)): # 下一个块就是要去的块就不用patch                continue            if project.arch.name in ARCH_X86:                fill_nop(bin, file_offset, last_instr.size, project.arch)                patch_value = ins_j_jmp_hex_x86(last_instr.address, childs[0], 'jmp')            patch_instruction(bin, file_offset, patch_value)        else:            instr = patch_instrs[parent]            file_offset = instr.address - base            # patch instructions starting from `cmovx` to the end of block            fill_nop(bin, file_offset, parent.addr +                     parent.size - base - file_offset, project.arch)            if project.arch.name in ARCH_X86:                # patch the cmovx instruction to jx instruction                patch_value = ins_j_jmp_hex_x86(instr.address, childs[0], instr.mnemonic[len('cmov'):])                patch_instruction(bin, file_offset, patch_value)                 file_offset += 6                # patch the next instruction to jmp instrcution                patch_value = ins_j_jmp_hex_x86(instr.address+6, childs[1], 'jmp')                patch_instruction(bin, file_offset, patch_value)    assert(ori_len == len(bin))           return bin if __name__ == "__main__":       md = Cs(CS_ARCH_X86,CS_MODE_64)    md.detail = True     filename = "babyparser_recover_main"    new_filename = filename    with open(filename, 'rb') as fp:        bin = fp.read()     project = angr.Project(filename, load_options={'auto_load_libs': False})    base = project.loader.main_object.mapped_base >> 12 << 12       start = 0x40fe20    the_last_jmp_block = 0x411448    #cfg = project.analyses.CFGFast(normalize=True)    cfg = project.analyses.CFGFast(normalize=True,force_complete_scan=False)    target_function = cfg.functions.get(start)    assert target_function != None     # end = start + target_function.size    supergraph = am_graph.to_supergraph(target_function.transition_graph)       # *******************GET BLOCK***************************    # get prologue_node(开始结点) and retn_node    prologue_nodes = []    retn_nodes = []    relevant_nodes = []    nop_nodes = []    patch_instrs = {}    for node in supergraph.nodes():        if supergraph.in_degree(node) == 0:            prologue_nodes.append(node)        elif supergraph.out_degree(node) == 0 :            retn_nodes.append(node)        elif supergraph.out_degree(node) == 1 and node.addr != the_last_jmp_block:            relevant_nodes.append(node)        elif supergraph.out_degree(node) == 2 :            nop_nodes.append(node)    print(prologue_nodes)    print(retn_nodes)      if len(prologue_nodes) != 1 or prologue_nodes[0].addr != start:        print("Something must be wrong...")        exit(0)     main_dispatcher_node = list(supergraph.successors(prologue_nodes[0]))[0]    relevant_block_addrs = [(node.addr) for node in relevant_nodes]    relevants = {}    for node in relevant_nodes+prologue_nodes+retn_nodes:        relevants[node.addr] = node    print('*******************relevant blocks************************')    print('prologue: %#x' % start)    print('main_dispatcher: %#x' % main_dispatcher_node.addr)    print('retn: ' , [hex(node.addr) for node in retn_nodes])    print('relevant_blocks:', [hex(addr) for addr in relevant_block_addrs])      print('*******************simulated execution*********************')    flow = collections.defaultdict(list)    instrs_size = 0    memset_count = 0    nop_instruc = set()     mu = Uc(UC_ARCH_X86, UC_MODE_64)    #init stack    mu.mem_map(0x80000000,0x10000 * 8)    # map 4MB memory for this emulation    mu.mem_map(base, 16 * 1024 * 1024)     # write machine code to be emulated to memory    mu.mem_write(0x401000, bin[0x2000:0x2000+0x19559])  # code segment    mu.mem_write(0x420dd0,bin[0x20dd0:0x20dd0+0x6270])  # data segment    mu.reg_write(UC_X86_REG_RSP, 0x80000000 + 0x10000 * 6)    mu.hook_add(UC_HOOK_CODE, hook_code) # 对每条指令hook    mu.hook_add(UC_HOOK_MEM_UNMAPPED, hook_mem_access)     #set function argv    mu.reg_write(UC_X86_REG_RDI, 1) # set argc     list_trace = {}    is_debug = False    queue = [(start, None)]     while len(queue) != 0:         env = queue.pop()        address = env[0]        context = env[1]         if address in flow:            continue         set_context(context)        node = relevants[address]        block = project.factory.block(address, size=node.size)  # 当前处理的块         has_branches = False        hook_addr = []         #检测代码块中是否有ollvm生成的分支        for ins in block.capstone.insns:            if ins.insn.mnemonic.startswith('cmov'):                has_branches = True                if node not in patch_instrs:                    patch_instrs[node] = ins                break         #代码块中有ollvm生成的分支        if has_branches:            ctx = get_context()            p1 = find_path(address, 0)            if p1 != None:                queue.append((p1, get_context()))                flow[address].append(p1)             set_context(ctx)            p2 = find_path(address, 1)             if p1 == p2:                p2 = None             if p2 != None:                queue.append((p2, get_context()))                flow[address].append(p2)        else:            p = find_path(address)            if p != None:                queue.append((p, get_context()))                flow[address].append(p)        # print(flow)    print('************************flow******************************')    for k, v in flow.items():        print('%#x: ' % k, [hex(child) for child in v])     print('************************fix******************************')    new_bin = fix(bytearray(bin), flow, nop_nodes, patch_instrs)    with open(new_filename,"wb") as fp:        fp.write(new_bin)

对于好几个关键函数进行去混淆以后，终于可以开始着手逆向了！

cpp stl 逆向

接下来就是逆向的问题了，先简单逆一下能知道，程序要求的输入是符号和数字，其中数字必须是0x[a-f][a-f][a-f][a-f] 符号只能是?!^| ，再加上题目说这是一个parser，我们可以猜到这是一个算式的解析。那么肯定代码里会出现stack 这个stl 的数据结构，而我对此并不是很熟悉。果然我在动调的时候发现了sub_4151B0是一个parser功能的函数，其中它的第一个参数是这样的结构：

很有可能这就是栈的结构，我们都知道栈的默认底层container是deque，因此去查了一下cpp里deque的实现：https://zhuanlan.zhihu.com/p/494261593，通过这篇博客，我们可以写出deque的结构体。当然还有vector也是逆向中很重要的数据结构：

struct deque_iter{        obj*  cur;        obj* begin;        obj* end;        obj* cur_node;};struct deque{        ptr  M_map;        size_t M_map_size;        deque_iter  start;        deque_iter  finish;};struct vector{        obj  begin[vector.size];        obj*  obj_end;           obj*  capacity_end;};

在ida里加入这些结构体以后再逆向，整个逻辑就清楚了很多。 ?! 相当于是() ，只有^ 和 | 是运算符。又根据明显的先序后序遍历能知道最后parser出来的是一个二叉树。因此知道了输入的结构是 ?0x|0x!^?0x|0x!

加密部分的处理

我们把上面处理结果的四个未知量从左到右设为a，b，c， d，最终的比对流程简化为：

sub_40F5B("hello123",d) ^ sub_40F5B("hello456",c) == cmp1

sub_411DE0("smithsmith666666", cmp1) ^ sub_411DE0("smithsmith777777", sub_40F5B(hello123,b) ^ sub_40F5B(hello456,a) ) == cmp2

通过对sbox的分析，以及密钥里smith的读音，可以直接猜出sub_411DE0其实是sm4 加密，但是我没有看出sub_40F5B是什么加密。

由于a b c d 四个未知量，其中每个未知量都只有$6^4$种可能，而且由于sub_40F5B是ECB模式的块加密，每一个未知量又可以分为两个部分，可能性进一步退化到$6^2$。因此可以采用爆破的方法。虽然我们不知道sub_40F5B是什么加密，但是也可以用unicorn 来进行模拟执行。

最终的解密代码如下：

from unicorn import *from unicorn.x86_const import *from capstone import *from capstone.x86 import *from itertools import productfrom tqdm import tqdm base = 0x3ff000def trans(a)->bytes:    ret = [0]*(len(a)*4)    for i in range(len(a)):        ret[i*4] = ord(a[i])    return bytes(ret) candi = []for c in product('abcdef',repeat=2):    candi.append(trans(c)) a = list(0xB997FEA9D35F1491.to_bytes(8,'little') + 0xF199D36FCF4A12C7.to_bytes(8,'little'))  # --------------------bruteforce enc--------------------# with open("./babyparser", 'rb') as fp:#     bin = fp.read() # def hook_code(uc, address, size, user_data):#     for ins in md.disasm(bin[address-base:address -base + size], address-base):#         # print(">>> Tracing instruction at 0x%x, instruction size = 0x%x" % (address, size))#         # print(">>> 0x%x:\t%s\t%s" % (ins.address, ins.mnemonic, ins.op_str)) #         if ins.mnemonic.startswith("call") :#             if(ins.op_str  == '0x2090'):  # hook memset twice#                 ptr = uc.reg_read(UC_X86_REG_RDI)#                 val = uc.reg_read(UC_X86_REG_ESI).to_bytes(1,'little')#                 siz = uc.reg_read(UC_X86_REG_EDX)#                 uc.mem_write(ptr,val*siz)#                 uc.reg_write(UC_X86_REG_RIP, address + size) # md = Cs(CS_ARCH_X86,CS_MODE_64)# md.detail = True# mu = Uc(UC_ARCH_X86, UC_MODE_64)# #init stack# mu.mem_map(0x80000000,0x10000 * 8)# # map 4MB memory for this emulation# mu.mem_map(base, 16 * 1024 * 1024) # # write machine code to be emulated to memory# mu.mem_write(0x401000, bin[0x2000:0x2000+0x19559])  # code segment# mu.mem_write(0x420dd0,bin[0x20dd0:0x20dd0+0x6270])  # data segment# mu.reg_write(UC_X86_REG_RSP, 0x80000000 + 0x10000 * 6)# mu.hook_add(UC_HOOK_CODE, hook_code) # 对每条指令hook# initial = mu.context_save()# for key in [b"hello123",b"hello456"]: # b"hello123"#     f = open(key.decode(), 'wb')#     for can in tqdm(candi):#         mu.context_restore(initial)#         mu.mem_write(0x80000010,key)#         mu.reg_write(UC_X86_REG_RDI,0x80000010) #         mu.mem_write(0x80000020,can)#         mu.reg_write(UC_X86_REG_RSI,0x80000020) #         mu.reg_write(UC_X86_REG_RDX,0x80000030)#         mu.reg_write(UC_X86_REG_ECX,8) #         mu.emu_start(0x40F5B0, 0x40F5F1) #         enced = mu.mem_read(0x80000030,8) #         f.write(can+enced)#     f.close()  b = list(0x26F04376032014A3.to_bytes(8,'little') + 0x4744333708D0E9AC.to_bytes(8,'little')) with open("hello123",'rb') as f:    con = f.read()h123 = {}for i in range(0,len(con),0x20):    h123[con[i+0x10:i+0x20]] = con[i:i+0x10]h456 = {}with open("hello456",'rb') as f:    con = f.read()for i in range(0,len(con),0x10):    h456[con[i+0x8:i+0x10]] = con[i:i+0x8] def  brute(cmp:list):    for n123 in tqdm(h123):        for n456_1 in h456:            for n456_2 in h456:                n456 = n456_1+n456_2                tmp = [n123[i]^n456[i] for i in range(16)]                if(tmp == list(cmp)):                    print(h123[n123],h456[n456[0:8]],h456[n456[8:16]]) #babe   cafe                    return # ?0xdead|0xbeef!^?0xcafe|0xbabe!import sm4k1 = sm4.SM4Key(b'smithsmith666666')tmp = k1.encrypt(bytes(a))print(tmp)cmp2 = [tmp[i]^b[i] for i in range(16)]k2 = sm4.SM4Key(b'smithsmith777777')cmp2 = k2.decrypt(bytes(cmp2))brute(cmp2) # beef   dead