Programming 01
Đề bài
1 2 | nc 15.164.75.32 1999 |
Lời giải
Connect thử chúng ta được màn hình như sau:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | PROGRAMING - WHITEHAT GRANDPRIX 06: --> COUNT THE NUMBER OF POSSIBLE TRIANGLES <-- HOW MANY TRIANGLES ARE CREATED BY N (1..N) NUMBER. N < 10^6 Example: N = 5 OUTPUT : 3 (2,3,4),(3,4,5),(2,4,5) ................/...................|................... .............../ ..................| .................. ............../ .................| ................. ............./ ................| ................ ............/ ...............| ............... .........../ ..............| .............. ........../____________.............|______............. n = 11 Answer: % |
1 2 | Vậy là đề bài yêu cầu tìm số hình tam giác có cạnh là số nguyên, có thể tạo được bằng các số tự nhiên từ 1 cho đến N. Vì N rất lớn (> 99999) nên khả năng cao là sẽ có công thức toán cho đáp án, ta có thể google hoặc ngồi phân tích thuật toán. Cơ mà mình dốt toán nên sẽ google :cry:. Code nhanh 1 chương trình tìm số tam giác theo đúng yêu cầu đề bài: |
1 2 3 4 5 6 7 8 9 10 11 | <span class="token keyword">from</span> itertools <span class="token keyword">import</span> permutations <span class="token keyword">for</span> N <span class="token keyword">in</span> <span class="token builtin">range</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">10</span><span class="token punctuation">)</span><span class="token punctuation">:</span> ans <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span> <span class="token keyword">for</span> a<span class="token punctuation">,</span> b<span class="token punctuation">,</span> c <span class="token keyword">in</span> permutations<span class="token punctuation">(</span><span class="token builtin">range</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> N<span class="token operator">+</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token keyword">if</span> a <span class="token operator">+</span> b <span class="token operator">></span> c <span class="token operator">and</span> b <span class="token operator">+</span> c <span class="token operator">></span> a <span class="token operator">and</span> a <span class="token operator">+</span> c <span class="token operator">></span> b<span class="token punctuation">:</span> ans<span class="token punctuation">.</span>append<span class="token punctuation">(</span><span class="token string">"-"</span><span class="token punctuation">.</span>join<span class="token punctuation">(</span><span class="token builtin">map</span><span class="token punctuation">(</span><span class="token builtin">str</span><span class="token punctuation">,</span> <span class="token builtin">sorted</span><span class="token punctuation">(</span><span class="token punctuation">[</span>a<span class="token punctuation">,</span> b<span class="token punctuation">,</span> c<span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> ans <span class="token operator">=</span> <span class="token builtin">set</span><span class="token punctuation">(</span>ans<span class="token punctuation">)</span> <span class="token comment"># print(ans)</span> <span class="token keyword">print</span><span class="token punctuation">(</span><span class="token builtin">len</span><span class="token punctuation">(</span>ans<span class="token punctuation">)</span><span class="token punctuation">)</span> |
rồi thử chạy với các N nhỏ (4, 5, 6, 7,…) thì ra dãy sau:
1 2 3 4 5 6 7 8 | ➜ whqual2020 python brute_triangle.py 1 3 7 13 22 34 |
Google thử dãy này thì ra kết quả: https://oeis.org/A173196
a(n-1) is the number of integer-sided scalene triangles with largest side <= n, including degenerate (i.e., collinear) triangles. a(n-2) is the number of non-degenerate integer-sided scalene triangles. – Alexander Evnin, Oct 12 2010
OK, vậy công việc chỉ còn implement công thức tính, kết nối và lấy flag thôi (chú ý offset của N đề bài so với n của dãy):
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | <span class="token keyword">from</span> netcatlib <span class="token keyword">import</span> Netcat nc <span class="token operator">=</span> Netcat<span class="token punctuation">(</span><span class="token string">'15.164.75.32'</span><span class="token punctuation">,</span> <span class="token number">1999</span><span class="token punctuation">)</span> resp <span class="token operator">=</span> nc<span class="token punctuation">.</span>read_until<span class="token punctuation">(</span><span class="token string">"Answer:"</span><span class="token punctuation">)</span> <span class="token keyword">while</span> <span class="token boolean">True</span><span class="token punctuation">:</span> <span class="token keyword">for</span> line <span class="token keyword">in</span> resp<span class="token punctuation">.</span>split<span class="token punctuation">(</span><span class="token string">"n"</span><span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token keyword">print</span><span class="token punctuation">(</span>line<span class="token punctuation">)</span> <span class="token keyword">if</span> <span class="token string">"n = "</span> <span class="token keyword">in</span> line<span class="token punctuation">:</span> N <span class="token operator">=</span> <span class="token builtin">int</span><span class="token punctuation">(</span>line<span class="token punctuation">[</span>line<span class="token punctuation">.</span>index<span class="token punctuation">(</span><span class="token string">"n = "</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token number">4</span><span class="token punctuation">:</span><span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token keyword">print</span><span class="token punctuation">(</span>N<span class="token punctuation">)</span> <span class="token keyword">break</span> K <span class="token operator">=</span> N <span class="token operator">-</span> <span class="token number">2</span> ans <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token number">4</span><span class="token operator">*</span>K<span class="token operator">**</span><span class="token number">3</span> <span class="token operator">+</span> <span class="token number">6</span><span class="token operator">*</span>K<span class="token operator">**</span><span class="token number">2</span> <span class="token operator">-</span> <span class="token number">4</span><span class="token operator">*</span>K <span class="token operator">-</span> <span class="token number">3</span> <span class="token operator">+</span> <span class="token number">3</span><span class="token operator">*</span><span class="token punctuation">(</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token operator">**</span>K<span class="token punctuation">)</span><span class="token operator">/</span><span class="token number">48</span> <span class="token keyword">print</span><span class="token punctuation">(</span><span class="token string">"ans = "</span><span class="token punctuation">,</span> ans<span class="token punctuation">)</span> nc<span class="token punctuation">.</span>write<span class="token punctuation">(</span><span class="token builtin">str</span><span class="token punctuation">(</span>ans<span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token string">"n"</span><span class="token punctuation">)</span> resp <span class="token operator">=</span> nc<span class="token punctuation">.</span>read_until<span class="token punctuation">(</span><span class="token string">":"</span><span class="token punctuation">)</span> <span class="token keyword">print</span><span class="token punctuation">(</span>resp<span class="token punctuation">)</span> |
Chạy và lấy flag:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 | ➜ whqual2020 python prog01.py PROGRAMING - WHITEHAT GRANDPRIX 06: --<span class="token operator">></span> COUNT THE NUMBER OF POSSIBLE TRIANGLES <span class="token operator"><</span>-- HOW MANY TRIANGLES ARE CREATED BY N <span class="token punctuation">(</span>1<span class="token punctuation">..</span>N<span class="token punctuation">)</span> NUMBER. N <span class="token operator"><</span> 10^6 Example: N <span class="token operator">=</span> 5 OUTPUT <span class="token keyword">:</span> 3 <span class="token punctuation">(</span>2,3,4<span class="token punctuation">)</span>,<span class="token punctuation">(</span>3,4,5<span class="token punctuation">)</span>,<span class="token punctuation">(</span>2,4,5<span class="token punctuation">)</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>/<span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>.<span class="token operator">|</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>. <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>./ <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token operator">|</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>/ <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>.<span class="token operator">|</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>. <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>./ <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token operator">|</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>/ <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>.<span class="token operator">|</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>. <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>./ <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token operator">|</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span> <span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>/____________<span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>.<span class="token operator">|</span>______<span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span><span class="token punctuation">..</span>. n <span class="token operator">=</span> 7 7 <span class="token punctuation">(</span><span class="token string">'ans = '</span>, 13<span class="token punctuation">)</span> Well done<span class="token operator">!</span> Let<span class="token string">'s accelerate.n = 9999 Answer: Well done! Let'</span>s accelerate.n <span class="token operator">=</span> 9999 9999 <span class="token punctuation">(</span><span class="token string">'ans = '</span>, 83270847499<span class="token punctuation">)</span> Great <span class="token operator">!</span> the last challenge. n <span class="token operator">=</span> 1000000 Answer: Great <span class="token operator">!</span> the last challenge. n <span class="token operator">=</span> 1000000 1000000 <span class="token punctuation">(</span><span class="token string">'ans = '</span>, 83332958333750000<span class="token punctuation">)</span> You are Victorious <span class="token keyword">:</span> You are Victorious <span class="token keyword">:</span> WhiteHat<span class="token punctuation">{</span>Y0u_h4v3_4_Sm4rt_Br41n<span class="token punctuation">}</span> <span class="token punctuation">(</span><span class="token string">'ans = '</span>, 83332958333750000<span class="token punctuation">)</span> Traceback <span class="token punctuation">(</span>most recent call last<span class="token punctuation">)</span>: File <span class="token string">"prog01.py"</span>, line 18, <span class="token keyword">in</span> <span class="token operator"><</span>module<span class="token operator">></span> resp <span class="token operator">=</span> nc.read_until<span class="token punctuation">(</span><span class="token string">":"</span><span class="token punctuation">)</span> File <span class="token string">"/Users/nguyen.anh.tien/ctf/whqual2020/netcatlib.py"</span>, line 22, <span class="token keyword">in</span> read_until self.buff +<span class="token operator">=</span> self.socket.recv<span class="token punctuation">(</span>1024<span class="token punctuation">)</span> socket.error: <span class="token punctuation">[</span>Errno 54<span class="token punctuation">]</span> Connection reset by peer |
Vậy flag là WhiteHat{Y0u_h4v3_4_Sm4rt_Br41n}.
Blockchain – Misc
Đề bài
1 2 3 4 5 | Blockchain application in IOT system. Using vulnerable chipset to generate public keys. http://52.78.210.118/Blockchain.zip |
Lời giải
Mới nhìn tên đề bài, cứ ngỡ là là sẽ có chút gì đó liên quan đến blockchain với hash, timestamp, block, vân vân nhưng sau khi làm xong, đơn giản lại là 1 bài crypto trá hình 
. Giải nén file zip ta có:
1 2 3 4 5 6 7 8 | . ├── 34a7370734caff5d129ad355f78f3ccf.pem ├── 8a95963d7bedd2b81ad09cd1838c7a4d.pem ├── block1.json ├── block2.json ├── block3.json └── flag.zip |
File flag.zip bên trong có một file flag.txt có password, nhiệm vụ của ta sẽ là tìm password để giải mã file này. Xem lại 2 file pem thì thấy public key rất ngắn, thêm hint đề bài Using vulnerable chipset to generate public keys. thì khả năng là sẽ factor được hoặc 2 public keys này sẽ có chung factor. Và đúng là đề bài theo hướng thứ 2. Nhanh chóng chúng ta tìm ra được p, q tương ứng cho 2 key:
1 2 3 4 5 6 7 8 9 | <span class="token comment"># 8a95963d7bedd2b81ad09cd1838c7a4d</span> p1 <span class="token operator">=</span> <span class="token number">1091951834898382993408357240646061116416467734213916798265279491274843400183</span> q1 <span class="token operator">=</span> <span class="token number">968357930958770928862265655524254201820039464684491130864944605493368598601</span> <span class="token comment"># 34a7370734caff5d129ad355f78f3ccf</span> p2 <span class="token operator">=</span> <span class="token number">1091951834898382993408357240646061116416467734213916798265279491274843400183</span> q2 <span class="token operator">=</span> <span class="token number">3602083547017910155331521957638413821351348404017103506647493207187611603783</span> |
cùng xem thử nội dung block1.json:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | <span class="token punctuation">{</span> <span class="token property">"data_block"</span><span class="token operator">:</span> <span class="token punctuation">[</span> <span class="token punctuation">{</span> <span class="token property">"34a7370734caff5d129ad355f78f3ccf"</span><span class="token operator">:</span> <span class="token punctuation">{</span> <span class="token property">"messger"</span><span class="token operator">:</span> <span class="token string">"864826346328927043007924641380681736981324987926997370887020532699182309378599192043216478265476219278213123962074508284028662403643532629433329761492"</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token punctuation">{</span> <span class="token property">"8a95963d7bedd2b81ad09cd1838c7a4d"</span><span class="token operator">:</span> <span class="token punctuation">{</span> <span class="token property">"messger"</span><span class="token operator">:</span> <span class="token string">"259242051785557714557594066190019826465030870294179284671916925100489488841761299528416294893049464518482888070747927907550583942630013791833474340284"</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> <span class="token punctuation">]</span> <span class="token punctuation">}</span> |
Ta thử decrypt với private key tương ứng cho 2 message sẽ ra plaintext, và thật ngạc nhiên là cả block 2, block 3 ta có thể làm tương tự (mà không cần quan tâm đến block đằng trước ?!!, có vẻ là do phần checking kia đã bị loại bỏ, chỉ còn lại data bên trong). Code nhanh file giải mã:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | <span class="token keyword">import</span> binascii <span class="token comment"># 8a95963d7bedd2b81ad09cd1838c7a4d</span> p1 <span class="token operator">=</span> <span class="token number">1091951834898382993408357240646061116416467734213916798265279491274843400183</span> q1 <span class="token operator">=</span> <span class="token number">968357930958770928862265655524254201820039464684491130864944605493368598601</span> d1 <span class="token operator">=</span> <span class="token number">890409172165972946654999517131765096619044495455563634699347004973962052351583003107345858884088740814369362782066954018932838938065269321325801558673</span> n1 <span class="token operator">=</span> p1<span class="token operator">*</span>q1 <span class="token comment"># 34a7370734caff5d129ad355f78f3ccf</span> p2 <span class="token operator">=</span> <span class="token number">1091951834898382993408357240646061116416467734213916798265279491274843400183</span> q2 <span class="token operator">=</span> <span class="token number">3602083547017910155331521957638413821351348404017103506647493207187611603783</span> d2 <span class="token operator">=</span> <span class="token number">693850823202558629985086506870478277795253330491028235428549797234329350960719509661597224650158883970045955832376666148611503822720520111138909455845</span> n2 <span class="token operator">=</span> p2<span class="token operator">*</span>q2 b1m1 <span class="token operator">=</span> <span class="token number">259242051785557714557594066190019826465030870294179284671916925100489488841761299528416294893049464518482888070747927907550583942630013791833474340284</span> b1m2 <span class="token operator">=</span> <span class="token number">864826346328927043007924641380681736981324987926997370887020532699182309378599192043216478265476219278213123962074508284028662403643532629433329761492</span> b2m1 <span class="token operator">=</span> <span class="token number">260259490441096686614518844301454718739843509738983969165420676005404297357230613482141235832583253831691051931351295653801889428212969414301414329852</span> b2m2 <span class="token operator">=</span> <span class="token number">3467074671076858427887425157777463145087476633275513864943463990703623032280801013924306443879332057123214793127862390154827554625137418534583896303616</span> b3m2 <span class="token operator">=</span> <span class="token number">1535086324597057729311343510271769159442400498252787851926410538373297030193590329732950032623600137243772129943527400615893561445637150940979108765230</span> b3m1 <span class="token operator">=</span> <span class="token number">182842058942028668693782090218012558408325328016978308589264490683273716484502724907545336344750909005728737352410277713521976130375761311818569486299</span> <span class="token keyword">def</span> <span class="token function">decrypt1</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token keyword">return</span> <span class="token builtin">pow</span><span class="token punctuation">(</span>x<span class="token punctuation">,</span> d1<span class="token punctuation">,</span> n1<span class="token punctuation">)</span> <span class="token keyword">def</span> <span class="token function">decrypt2</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span><span class="token punctuation">:</span> <span class="token keyword">return</span> <span class="token builtin">pow</span><span class="token punctuation">(</span>x<span class="token punctuation">,</span> d2<span class="token punctuation">,</span> n2<span class="token punctuation">)</span> <span class="token keyword">def</span> <span class="token function">de</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span><span class="token punctuation">:</span> k <span class="token operator">=</span> <span class="token builtin">hex</span><span class="token punctuation">(</span>x<span class="token punctuation">)</span><span class="token punctuation">[</span><span class="token number">2</span><span class="token punctuation">:</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token keyword">if</span> <span class="token builtin">len</span><span class="token punctuation">(</span>k<span class="token punctuation">)</span> <span class="token operator">%</span> <span class="token number">2</span> <span class="token operator">!=</span> <span class="token number">0</span><span class="token punctuation">:</span> k <span class="token operator">=</span> <span class="token string">"0"</span> <span class="token operator">+</span> k <span class="token keyword">return</span> binascii<span class="token punctuation">.</span>unhexlify<span class="token punctuation">(</span>k<span class="token punctuation">)</span> <span class="token keyword">print</span><span class="token punctuation">(</span>de<span class="token punctuation">(</span>decrypt1<span class="token punctuation">(</span>b1m1<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">print</span><span class="token punctuation">(</span>de<span class="token punctuation">(</span>decrypt2<span class="token punctuation">(</span>b1m2<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">print</span><span class="token punctuation">(</span>de<span class="token punctuation">(</span>decrypt1<span class="token punctuation">(</span>b2m1<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">print</span><span class="token punctuation">(</span>de<span class="token punctuation">(</span>decrypt2<span class="token punctuation">(</span>b2m2<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">print</span><span class="token punctuation">(</span>de<span class="token punctuation">(</span>decrypt1<span class="token punctuation">(</span>b3m1<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token keyword">print</span><span class="token punctuation">(</span>de<span class="token punctuation">(</span>decrypt2<span class="token punctuation">(</span>b3m2<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span> |
và chạy:
1 2 3 4 5 6 7 8 | ➜ whqual2020 python blockchain.py Password using open flag.zip Do you understand the blockchain? Password = Password1+Password2 flag in flag.txt Password2:'<a class="__cf_email__" href="/cdn-cgi/l/email-protection">[email protected]</a>!4P##Ij' Password1:'irVOwoJR7d' |
Dùng password [email protected]!4P##Ij giải nén file flag.zip ta nhận được một file mới với nội dung là base64, decode ra được 1 file ảnh QR. Scan QR code này ta có flag:
Flag: Whitehat{the_ flag_blockchain_ iot}