{"id":1339,"date":"2026-05-09T18:42:26","date_gmt":"2026-05-09T10:42:26","guid":{"rendered":"http:\/\/shr1mp.top\/?p=1339"},"modified":"2026-05-14T21:58:06","modified_gmt":"2026-05-14T13:58:06","slug":"pycc-misc","status":"publish","type":"post","link":"https:\/\/shr1mp.top\/index.php\/2026\/05\/09\/pycc-misc\/","title":{"rendered":"PYCC—misc"},"content":{"rendered":"\n

\u521d\u8d5b<\/h2>\n\n\n\n
\n

\u4e3a\u4ec0\u4e48\u8fd9\u73a9\u610f\u8981\u8bbe\u7acb\u5728\u4e94\u4e00\u5047\u671f\u671f\u95f4\uff1f\uff1f\uff1f\u4f60\u662f\u89c9\u5f97\u6211\u5047\u671f\u90fd\u4f1a\u7528\u6765\u7b49\u4f60\u51fa\u9898\u7136\u540e\u8ba4\u771f\u89e3\u9898\u5417\u3002\u8fd8\u5b66\u6821\u5361\u534a\u8fdb\u590d\u8d5b\uff0c\u8fd8\u8981\u7ed9\u94b1\u3002\u8fd9wp\u548cflag\u4e5f\u6ee1\u5929\u98de\uff0c\u5237\u65b0\u4e86\u6211\u5bf9\u767d\u540d\u5355\u6bd4\u8d5b\u7684\u8ba4\u77e5<\/p>\n<\/blockquote>\n\n\n\n

misc1<\/h3>\n\n\n\n

\u9898\u76ee\u4fe1\u606f<\/p>\n\n\n\n

    \n
  • \u9898\u76ee\u540d\uff1a\u53cc\u6821\u533a\u6765\u4fe1<\/li>\n\n\n\n
  • \u5206\u503c\uff1a100<\/li>\n\n\n\n
  • \u7c7b\u578b\uff1a\u9690\u5199 \/ \u97f3\u9891+\u56fe\u7247\u53d6\u8bc1<\/li>\n<\/ul>\n\n\n\n

    \u9898\u9762\u63d0\u793a\uff1a<\/p>\n\n\n\n

      \n
    • \u201c\u522b\u53ea\u770b\u56fe\uff0c\u5e7f\u64ad\u66f4\u91cd\u8981\u201d<\/li>\n\n\n\n
    • \u201c\u627e\u5230\u987a\u5e8f\uff0c\u53e3\u4ee4\u81ea\u7136\u4f1a\u51fa\u73b0\u201d<\/li>\n<\/ul>\n\n\n\n

      \u9644\u4ef6\uff1a<\/p>\n\n\n\n

        \n
      • shnu.jpg<\/code><\/li>\n\n\n\n
      • campus_broadcast.wav<\/code><\/li>\n<\/ul>\n\n\n\n

        \u53ef\u4ee5\u63a8\u65ad\uff1a<\/p>\n\n\n\n

          \n
        1. \u56fe\u7247\u91cc\u53ef\u80fd\u85cf\u6709\u989d\u5916\u6570\u636e\uff08\u5e38\u89c1\u4e3a\u5c3e\u90e8\u62fc\u63a5\u538b\u7f29\u5305\uff09\u3002<\/li>\n\n\n\n
        2. \u5e7f\u64ad\u97f3\u9891\u91cc\u4f1a\u7ed9\u51fa\u538b\u7f29\u5305\u5bc6\u7801\u6216\u62fc\u63a5\u987a\u5e8f\u3002<\/li>\n<\/ol>\n\n\n\n

          \u89e3\u9898\u8fc7\u7a0b<\/h4>\n\n\n\n

          1. \u4ece\u56fe\u7247\u4e2d\u63d0\u53d6\u9690\u85cf\u538b\u7f29\u5305<\/p>\n\n\n\n

          \u68c0\u67e5 shnu.jpg<\/code> \u540e\u53d1\u73b0\u5176 JPEG \u7ed3\u675f\u6807\u8bb0 FF D9<\/code> \u540e\u4ecd\u6709\u989d\u5916\u6570\u636e\uff0c\u5e76\u4e14\u5b58\u5728 Rar!\\x1A\\x07<\/code> \u5934\u3002\u56e0\u6b64\u53ef\u4ece JPEG \u5c3e\u90e8\u622a\u51fa\u4e00\u4e2a\u9690\u85cf\u7684 RAR<\/code> \u6587\u4ef6\u3002<\/p>\n\n\n\n

          2. \u7531\u5e7f\u64ad\u5f97\u5230\u5bc6\u7801\u4e0e\u987a\u5e8f<\/p>\n\n\n\n

          \u97f3\u9891\u9690\u5199\uff0c\u8fd9\u91cc\u7528ffmpeg\uff1a<\/p>\n\n\n\n

          ffmpeg -i input.wav -filter_complex \"showspectrumpic=s=2400x800:mode=combined:scale=log\" spec.png<\/code><\/pre>\n\n\n\n
          \"\"\/<\/div><\/figure>\n\n\n\n
          \u6839\u636e\u97f3\u9891\u9891\u8c31\/\u8bed\u97f3\u63d0\u793a\u53ef\u5f97\u5230\u62fc\u97f3\u5e8f\u5217\uff1ahou de bo xue qiu shi du xing<\/code><\/p>\n\n\n\n
          \u8fdb\u4e00\u6b65\u53d6\u5404\u8bcd\u9996\u5b57\u6bcd\u5f97\u5230\u5bc6\u7801\uff1ahdbxqsdx<\/code><\/p>\n\n\n\n
          \u540c\u65f6\u8fd9\u4e32\u8bcd\u672c\u8eab\u5c31\u662f\u788e\u7247\u6587\u4ef6\u7684\u62fc\u63a5\u987a\u5e8f\uff1a[hou, de, bo, xue, qiu, shi, du, xing]<\/code>\uff08\u4ed6\u4eec\u5b66\u6821\u6821\u8bad\uff09<\/p>\n\n\n\n
          3. \u89e3\u538b\u5e76\u62fc\u63a5\u788e\u7247<\/p>\n\n\n\n
          \u4f7f\u7528\u5bc6\u7801\u89e3\u5f00\u9690\u85cf RAR\uff0c\u5f97\u5230\u76ee\u5f55 campus_fragments\/<\/code> \u4e0b\u591a\u4e2a\u6587\u672c\u788e\u7247\u3002\u6309\u4e0a\u9762\u7684\u987a\u5e8f\u8bfb\u53d6\u5e76\u62fc\u63a5\u5185\u5bb9\uff0c\u6700\u7ec8\u5305\u4e0a ISCC{}<\/code> \u5373\u5f97\u5230 flag\u3002<\/p>\n\n\n\n
          \u5173\u952e\u811a\u672c\u601d\u8def<\/p>\n\n\n\n
            \n
          • \u5728 shnu.jpg<\/code> \u4e2d\u5b9a\u4f4d JPEG \u7ed3\u675f\u4f4d\u7f6e\u3002<\/li>\n\n\n\n
          • \u4ece\u7ed3\u675f\u4f4d\u7f6e\u540e\u67e5\u627e RAR \u6587\u4ef6\u5934\u5e76\u5199\u51fa hidden.rar<\/code>\u3002<\/li>\n\n\n\n
          • \u4f7f\u7528 7z<\/code> + \u5bc6\u7801 hdbxqsdx<\/code> \u89e3\u538b\u3002<\/li>\n\n\n\n
          • \u4f9d\u5e8f\u8bfb\u53d6 hou,de,bo,xue,qiu,shi,du,xing<\/code> \u6587\u4ef6\u5185\u5bb9\u62fc\u63a5\u3002<\/li>\n\n\n\n
          • \u8f93\u51fa ISCC{...}<\/code>\u3002<\/li>\n<\/ul>\n\n\n\n
            \u6700\u7ec8 Flag<\/p>\n\n\n\n
            ISCC{wE3rT5yU7iO9pL0kJ2hG4fD6sA8qQ}<\/code><\/pre>\n\n\n\n
            misc2<\/h3>\n\n\n\n
            \u955c\u5385\u4e2d\u7684\u56de\u54cd (Echoes in the Mirror Hall)<\/p>\n\n\n\n
            \n
            \u8fd9\u5929\u4f60\u7684\u540c\u4f34\u5728\u63a2\u7d22\u5931\u843d\u7684\u4e1d\u83ab\u738b\u56fd\u65f6\u8bef\u5165\u4e86\u4e00\u4e2a\u795e\u79d8\u7684\u955c\u5385\uff0c\u91cc\u9762\u8426\u7ed5\u7740\u4e00\u6bb5\u91cd\u590d\u64ad\u653e\u7684\u97f3\u4e50\uff0c\u5e76\u6709\u56fe\u50cf\u6620\u5c04\u5728\u5468\u8fb9\u7684\u955c\u5b50\u4e2d\u3002\u4f60\u7684\u540c\u4f34\u5c06\u955c\u5385\u4e2d\u7684\u6240\u89c1\u6240\u542c\u5f55\u5236\u6210\u4e00\u6bb5\u5f71\u50cf\u53d1\u7ed9\u4e86\u4f60\u3002\u73b0\u5728\uff0c\u8bf7\u89e3\u5f00\u955c\u5385\u7684\u79d8\u5bc6\uff0c\u62ef\u6551\u4f60\u7684\u540c\u4f34\u5427\uff01<\/p>\n<\/blockquote>\n\n\n\n
            \u9898\u76ee\u7ed9\u51fa\u4e00\u4e2a 40 \u79d2\u7684 CGI \u89c6\u9891 task.mp4<\/code>\u2014\u2014\u6444\u50cf\u673a\u5728\u4e00\u6761\u5e03\u6ee1\u83f1\u5f62\u955c\u9762\u7684\u8d70\u5eca\u91cc\u5300\u901f\u524d\u8fdb\uff0cBGM \u5faa\u73af\u64ad\u653e\u3002“\u56de\u54cd”(echo)<\/strong> \u548c “\u91cd\u590d\u64ad\u653e\u7684\u97f3\u4e50”<\/strong> \u662f\u5173\u952e\u7ebf\u7d22\uff0c\u63d0\u793a\u4fe1\u606f\u85cf\u5728 \u97f3\u9891<\/strong> \u800c\u4e0d\u662f \u56fe\u50cf<\/strong> \u91cc\u3002<\/p>\n\n\n\n
            \u89e3\u9898\u6d41\u7a0b\u6982\u89c8<\/h4>\n\n\n\n
            attachment-4.zip  \u2500\u2500\u2460\u2500\u2500\u25ba  task.mp4   \u2500\u2500\u2461\u2500\u2500\u25ba  audio.wav\n                                                 \u2502\n                                                 \u2462 \u5012\u8c31\u5206\u6790\n                                                 \u25bc\n                                           \u8bc6\u522b\u53cc\u56de\u58f0 d0=100 \/ d1=130\n                                                 \u2502\n                                                 \u2463 Echo Hiding \u89e3\u7801\n                                                 \u25bc\n                                              100 \u5b57\u8282\u6bd4\u7279\u6d41\n                                                 \u2502\n                                                 \u2464 \u6309 Morse \u5207\u5206\n                                                 \u25bc\n                                      xxxxxxxxxxxx\n                                                 \u2502\n                                                 \u2465 \u5957 flag\n                                                 \u25bc\n                                   ISCC{xxxxxxxxxxx}<\/code><\/pre>\n\n\n\n
            \n\n\n\n
            Step 1 \u2014 ZIP \u4f2a\u52a0\u5bc6\u7ed5\u8fc7<\/h4>\n\n\n\n
            \u76f4\u63a5 unzip<\/code> \/ 7z \u90fd\u63d0\u793a\u9700\u8981\u5bc6\u7801\u3002\u5bf9\u6bd4\u5c40\u90e8\u6587\u4ef6\u5934\u4e0e\u4e2d\u592e\u76ee\u5f55\u7684 GPB (General Purpose Bit) flag<\/strong>\uff1a<\/p>\n\n\n\n
            \u5c40\u90e8\u6587\u4ef6\u5934 @ 0x00     : 00 00  \u2190 \u672a\u52a0\u5bc6\n\u4e2d\u592e\u76ee\u5f55\u5934 @ 0x1001e4a: 01 00  \u2190 \u58f0\u79f0\u52a0\u5bc6<\/code><\/pre>\n\n\n\n
            \u8fd9\u662f\u5178\u578b\u7684 \u4f2a\u52a0\u5bc6<\/strong>\uff1a\u628a\u4e2d\u592e\u76ee\u5f55\u91cc\u90a3\u4e00\u4f4d\u5f3a\u5236\u6e05\u96f6\u5373\u53ef\u3002<\/p>\n\n\n\n
            with open('attachment-4.zip', 'rb') as f:\n    data = bytearray(f.read())\ndata[0x1001e4a:0x1001e4a+2] = b'\\x00\\x00'\nwith open('fixed.zip', 'wb') as f:\n    f.write(data)\n\n$ unzip fixed.zip\nArchive:  fixed.zip\n  inflating: task.mp4<\/code><\/pre>\n\n\n\n
            \u5f97\u5230 task.mp4<\/code>\uff0816,801,733 bytes\uff0c1280\u00d7720\uff0cH.264 + AAC\uff0c40s\uff09\u3002<\/p>\n\n\n\n
            Step 2 \u2014 \u7ea2\u9cb1\u9c7c\uff1a\u89c6\u9891\u91cc\u7684\u8ff7\u5bab<\/h4>\n\n\n\n
            \u9996\u5148\u5bf9\u89c6\u9891\u672c\u8eab\u505a\u4e86\u5927\u91cf\u5206\u6790\uff0c\u8fd9\u4e9b\u6700\u7ec8\u90fd\u8bc1\u660e\u662f red herring<\/strong>\uff0c\u4f46\u503c\u5f97\u8bb0\u5f55\u4ee5\u514d\u540e\u6765\u8005\u91cd\u8d70\uff1a<\/p>\n\n\n\n
            \u6000\u7591\u70b9<\/th>\u9a8c\u8bc1\u65b9\u6cd5<\/th>\u7ed3\u8bba<\/th><\/tr><\/thead>
            \u5730\u677f\/\u5899\u9762\/\u5929\u82b1\u677f\u85cf\u5b57<\/td>\u900f\u89c6\u77eb\u6b63 + Canny + \u8f6e\u5ed3\u5206\u6790 (24 \u5e27\u8de8\u5ea6)<\/td>\u53ea\u662f\u5bf9\u79f0\u955c\u9762\u5efa\u6a21<\/td><\/tr>
            \u5e27\u95f4 LSB \u9690\u5199<\/td>frame_lsb.py<\/code> \u7edf\u8ba1\u6bd4\u7279\u7ffb\u8f6c\u7387<\/td>\u2248 48%\uff0c\u7eaf\u538b\u7f29\u566a\u58f0<\/td><\/tr>
            Mirror \u9762\u677f\u5bf9\u79f0\u5dee<\/td>\u5de6\u53f3\u955c\u50cf mirror_diff<\/code><\/td>\u4ec5 H.264 \u91cf\u5316\u8bef\u5dee<\/td><\/tr>
            \u6d88\u5931\u70b9\u5750\u6807\u53d8\u5316<\/td>vanishing_point_f*.png<\/code><\/td>\u6444\u50cf\u673a\u5300\u901f\u524d\u8fdb\uff0c\u65e0\u8c03\u5236<\/td><\/tr>
            SEI NAL \u9644\u52a0\u6570\u636e<\/td>\u624b\u5de5\u89e3 AVCC<\/td>\u6709\u5f02\u5e38\uff0c\u89c1\u4e0b\u6587<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
            2.1 MP4 \u91cc\u7684\u5de8\u578b SEI<\/p>\n\n\n\n
            \u5728 mdat<\/code> \u91cc\u9762\u624b\u52a8\u904d\u5386 AVCC NAL\uff1a<\/p>\n\n\n\n
            offset 0x28          mdat box, size=16,776,650\n...\noffset 0xb75cc8      NAL type=6 (SEI), size=2,757,867 bytes  \u2190\u2190 \u53cd\u5e38\uff01<\/code><\/pre>\n\n\n\n
            \u4e00\u4e2a 40 \u79d2\u7684 H.264 \u89c6\u9891\u91cc\u51fa\u73b0 2.7 MB \u7684 SEI<\/strong>\uff0c\u975e\u5e38\u53ef\u7591\u3002\u89e3 RBSP (\u53bb\u6389 0x03 \u9632\u7ade\u4e89\u5b57\u8282) \u540e\u53d1\u73b0\uff1a<\/p>\n\n\n\n
              \n
            • \u524d 17,380 \u5b57\u8282\u662f 127 \u6761\u5408\u6cd5 SEI \u5b50\u6d88\u606f<\/li>\n\n\n\n
            • SEI stop bit 0x80<\/code> \u4e4b\u540e \u62fc\u63a5\u4e86 2,740,201 bytes \u7684\u4efb\u610f\u6570\u636e<\/strong><\/li>\n<\/ul>\n\n\n\n
              \u8fd9\u5806\u5c3e\u90e8\u6570\u636e\u8bd5\u4e86 AES-ECB\/CBC (\u5404\u79cd key\uff1aMorse \u660e\u6587\u3001SHA256\u3001echo bytes)\u3001RC4\u3001XOR\uff0c\u5168\u90e8\u5931\u8d25\u2014\u2014\u6ca1\u6709\u4efb\u4f55 magic bytes\u3002\u63a8\u6d4b\u53ea\u662f \u51fa\u9898\u4eba\u585e\u8fdb\u53bb\u7684\u8bf1\u9975 \/ \u5bb9\u91cf\u586b\u5145<\/strong>\uff0c\u4e0d\u662f\u771f\u6b63\u7684 flag \u8f7d\u4f53\u3002<\/p>\n\n\n\n
              \n
              \u6559\u8bad\uff1a\u522b\u8ba9”\u770b\u8d77\u6765\u5f02\u5e38”\u5c31\u53d8\u6210”\u4e00\u5b9a\u6709\u6599”<\/strong>\u3002\u5c3e\u90e8\u71b5\u63a5\u8fd1 8.0 + \u6ca1\u6709\u53ef\u89e3\u7ed3\u6784 = \u8981\u4e48\u662f\u4e8c\u6b21\u52a0\u5bc6\u3001\u8981\u4e48\u662f\u586b\u5145\u3002\u672c\u9898\u5c5e\u4e8e\u540e\u8005\u3002<\/p>\n<\/blockquote>\n\n\n\n
              \n\n\n\n
              Step 3 \u2014 \u97f3\u9891\u63d0\u53d6\u4e0e\u6574\u4f53\u5206\u6790<\/h4>\n\n\n\n
              ffmpeg -i task.mp4 -vn -acodec pcm_s16le audio.wav<\/code><\/pre>\n\n\n\n
              \u5f97\u5230 PCM 16-bit \u7acb\u4f53\u58f0\uff0c44100 Hz\uff0c1,764,352 samples (40.01 s)\u3002<\/p>\n\n\n\n
              import scipy.io.wavfile as wav\nimport numpy as np\nsr, x = wav.read('audio.wav')        # (1764352, 2)\nL, R = x[:, 0].astype(np.float32), x[:, 1].astype(np.float32)\nprint(np.corrcoef(L, R)[0, 1])       # 0.9999... \u21d2 \u53cc\u58f0\u9053\u51e0\u4e4e\u5b8c\u5168\u76f8\u540c<\/code><\/pre>\n\n\n\n
              \u9891\u8c31 (spec_*.png<\/code>) \u770b\u4e0a\u53bb\u662f\u666e\u901a\u7684\u73af\u5883\u4e50\uff0c\u6ca1\u6709 SSTV tone\u3001\u6ca1\u6709 FSK\u3001\u6ca1\u6709 DTMF<\/strong>\u3002\u4e8e\u662f\u628a\u6ce8\u610f\u529b\u8f6c\u5230 \u56de\u58f0<\/strong> \u672c\u8eab\u3002<\/p>\n\n\n\n
              \n\n\n\n
              Step 4 \u2014 \u5012\u8c31\u5206\u6790\u53d1\u73b0\u56de\u58f0\u5ef6\u8fdf<\/h4>\n\n\n\n
              Echo Hiding (Bender 1996) \u6700\u76f4\u63a5\u7684\u7834\u6cd5\u662f \u5012\u8c31 (cepstrum)<\/strong>\uff1a<\/p>\n\n\n\n
              $$c[n] = \\mathrm{IFFT}\\bigl(\\log \\lvert \\mathrm{FFT}(x[n]) \\rvert^2\\bigr)$$<\/p>\n\n\n\n
              \u56de\u58f0 x[n] + \u03b1\u00b7x[n-d]<\/code> \u4f1a\u5728\u5012\u8c31\u7684 n = d<\/code> \u5904\u5f62\u6210\u5c16\u5cf0\u3002<\/p>\n\n\n\n
              import numpy as np, scipy.io.wavfile as wav\nsr, x = wav.read('audio.wav')\nsig = x[:, 0].astype(np.float32)\n\nspec = np.fft.rfft(sig[:1 << 20])\ncep  = np.fft.irfft(np.log(np.abs(spec) ** 2 + 1e-10))\ntop = np.argsort(cep[1:500])[-10:][::-1]\nprint(top + 1)\n# \u2192 [100 130 200 260 ...]<\/code><\/pre>\n\n\n\n
              \u4e24\u6761\u660e\u663e\u7684\u72ec\u7acb\u5ef6\u8fdf<\/strong>\uff1a<\/p>\n\n\n\n
                \n
              • d0 = 100<\/code> samples (\u2248 2.27 ms)<\/li>\n\n\n\n
              • d1 = 130<\/code> samples (\u2248 2.95 ms)<\/li>\n<\/ul>\n\n\n\n
                \u8fd9\u662f\u7ecf\u5178\u7684 \u53cc\u5ef6\u8fdf Echo Hiding<\/strong>\uff1abit 0 \u2192 \u5ef6\u8fdf d0<\/code>\uff0cbit 1 \u2192 \u5ef6\u8fdf d1<\/code>\uff0c\u901a\u8fc7\u6bd4\u8f83\u4e24\u4e2a\u5ef6\u8fdf\u5728\u5012\u8c31\u4e0a\u7684\u80fd\u91cf\u5224\u51b3\u5373\u53ef\u3002<\/p>\n\n\n\n
                \n\n\n\n
                Step 5 \u2014 Echo Hiding \u6bd4\u7279\u89e3\u7801<\/h4>\n\n\n\n
                import numpy as np, scipy.io.wavfile as wav\n\ndef decode_echo(sig, window, d0=100, d1=130):\n    bits = []\n    for off in range(0, len(sig) - window + 1, window):\n        seg = sig[off:off + window]\n        spec = np.fft.rfft(seg)\n        logp = np.log(np.abs(spec) ** 2 + 1e-10)\n        cep  = np.fft.irfft(logp)\n        p0 = max(cep[max(1, d0 - 2):d0 + 3])\n        p1 = max(cep[max(1, d1 - 2):d1 + 3])\n        bits.append(0 if p0 > p1 else 1)\n    return bits\n\nsr, x = wav.read('audio.wav')\nbits = decode_echo(x[:, 0].astype(np.float32), window=2205)  # 50 ms\/bit\nprint(len(bits))                # 800 bits<\/code><\/pre>\n\n\n\n
                \u7a97\u5bbd ws = 2205 samples = 50 ms<\/code> \u662f\u901a\u8fc7\u626b\u63cf 1000~8000 \u8bd5\u51fa\u6765\u7684\u2014\u2014\u5728\u8fd9\u4e2a\u503c\u4e0a\u524d 74 \u5b57\u8282\u662f\u53ef\u6253\u5370 ASCII\uff0c\u4e14\u6bcf\u4e2a bit \u7684\u7f6e\u4fe1\u5ea6 (|peak1 \u2212 peak0|<\/code>) \u6700\u9ad8\u3002<\/p>\n\n\n\n
                nbytes = len(bits) \/\/ 8\nby = bytes(int(''.join(map(str, bits[i*8:(i+1)*8])), 2) for i in range(nbytes))\nprint(by[:80])<\/code><\/pre>\n\n\n\n
                \u8f93\u51fa\uff1a<\/p>\n\n\n\n
                b'..--- ..--.. ..- .--- -..-. -.-- -.--. ..--- ... .-.-. ...-- .-.. - .-- -.\\x00...'<\/code><\/pre>\n\n\n\n
                \u524d 74 \u5b57\u8282\u662f \u7a7a\u683c + \u70b9\u5212\u7684 Morse \u7801<\/strong>\uff0c\u7b2c 75 \u5b57\u8282\u4e4b\u540e\u7a81\u7136\u662f \\x00<\/code> \/ \u4e71\u7801\u2014\u2014\u8fd9\u548c echo_conf.py<\/code> \u8f93\u51fa\u7684\u7f6e\u4fe1\u5ea6\u543b\u5408\uff1a<\/p>\n\n\n\n
                byte idx<\/th>min conf<\/th>\u72b6\u6001<\/th><\/tr><\/thead>
                0 \u2013 73<\/td>\u2265 0.527<\/td>\u6e05\u6670<\/td><\/tr>
                74<\/td>0.084<\/td>\u6d88\u606f\u8fb9\u754c<\/strong><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                \n\n\n\n
                Step 6 \u2014 Morse \u89e3\u7801<\/h4>\n\n\n\n
                \u62ff\u5230 74 \u5b57\u8282\u7684 Morse \u6587\u672c\uff1a<\/p>\n\n\n\n
                ..--- ..--.. ..- .--- -..-. -.-- -.--. ..--- ... .-.-. ...-- .-.. - .-- -.<\/code><\/pre>\n\n\n\n
                \u7528 ITU-R M.1677 \u6807\u51c6\u8868<\/strong>\uff08\u542b\u6570\u5b57\u3001\u6807\u70b9\uff09 \u5bf9\u6bcf\u4e2a group \u67e5\u8868\uff1a<\/p>\n\n\n\n
                Morse<\/th>\u5b57\u7b26<\/th><\/tr><\/thead>
                ..---<\/code><\/td>2<\/code><\/td><\/tr>
                ..--..<\/code><\/td>?<\/code><\/td><\/tr>
                ..-<\/code><\/td>U<\/code><\/td><\/tr>
                .---<\/code><\/td>J<\/code><\/td><\/tr>
                -..-.<\/code><\/td>\/<\/code><\/td><\/tr>
                -.--<\/code><\/td>Y<\/code><\/td><\/tr>
                -.--.<\/code><\/td>(<\/code><\/td><\/tr>
                ..---<\/code><\/td>2<\/code><\/td><\/tr>
                ...<\/code><\/td>S<\/code><\/td><\/tr>
                .-.-.<\/code><\/td>+<\/code><\/td><\/tr>
                ...--<\/code><\/td>3<\/code><\/td><\/tr>
                .-..<\/code><\/td>L<\/code><\/td><\/tr>
                -<\/code><\/td>T<\/code><\/td><\/tr>
                .--<\/code><\/td>W<\/code><\/td><\/tr>
                -.<\/code><\/td>N<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                MORSE = {\n    '.-':'A','-...':'B','-.-.':'C','-..':'D','.':'E','..-.':'F','--.':'G',\n    '....':'H','..':'I','.---':'J','-.-':'K','.-..':'L','--':'M','-.':'N',\n    '---':'O','.--.':'P','--.-':'Q','.-.':'R','...':'S','-':'T','..-':'U',\n    '...-':'V','.--':'W','-..-':'X','-.--':'Y','--..':'Z',\n    '-----':'0','.----':'1','..---':'2','...--':'3','....-':'4','.....':'5',\n    '-....':'6','--...':'7','---..':'8','----.':'9',\n    '.-.-.-':'.','--..--':',','..--..':'?','-.-.--':'!',\n    '-....-':'-','-..-.':'\/','-.--.':'(','-.--.-':')',\n    '.----.':\"'\",'---...':':','-.-.-.':';','.-.-.':'+','-...-':'=',\n    '.-..-.':'\"','...-..-':'$','.--.-.':'@',\n}\nmsg = '..--- ..--.. ..- .--- -..-. -.-- -.--. ..--- ... .-.-. ...-- .-.. - .-- -.'\nprint(''.join(MORSE[g] for g in msg.split()))<\/code><\/pre>\n\n\n\n
                \n\n\n\n
                Step 7 \u2014 \u6784\u9020 Flag<\/h4>\n\n\n\n
                ISCC \u7684\u6807\u51c6\u683c\u5f0f ISCC{...}<\/code>\uff0c\u628a\u89e3\u51fa\u7684\u660e\u6587\u5957\u4e0a\u5373\u53ef\uff1a<\/p>\n\n\n\n
                > \u6ce8\u610f\uff1a\u660e\u6587\u91cc\u51fa\u73b0\u7684 `?` `\/` `(` `+` \u8fd9\u4e9b\"\u975e\u6b63\u5e38 flag \u5b57\u7b26\"\u4e0d\u662f\u89e3\u9519\u4e86\uff0c\u800c\u662f\u9898\u76ee\u6545\u610f\u7528 Morse **\u6807\u70b9\u8868** \u91cc\u7684\u5b57\u7b26\u2014\u2014\u6b63\u597d\u914d\u5408 `..--..`\u3001`-..-.`\u3001`-.--.`\u3001`.-.-.` \u8fd9\u51e0\u4e2a\u957f\u5ea6 5~6 \u7684 Morse group\uff0c\u8ba9 74 \u5b57\u8282\u7684 payload \u5bf9\u9f50\u5230 bit \u8fb9\u754c\u3002\n\n---\n\n## \u9644\uff1a\u4e00\u4f53\u5316\u811a\u672c\n\n```python\n\"\"\"misc22 one-shot solver.\"\"\"\nimport numpy as np, scipy.io.wavfile as wav, subprocess, pathlib\n\n# 1. ZIP \u4f2a\u52a0\u5bc6\u4fee\u590d\nz = pathlib.Path('attachment-4.zip').read_bytes()\npathlib.Path('fixed.zip').write_bytes(z[:0x1001e4a] + b'\\x00\\x00' + z[0x1001e4a+2:])\nsubprocess.run(['unzip', '-o', 'fixed.zip'], check=True)\n\n# 2. \u62bd\u97f3\u8f68\nsubprocess.run(['ffmpeg', '-y', '-i', 'task.mp4', '-vn',\n                '-acodec', 'pcm_s16le', 'audio.wav'], check=True)\n\n# 3. Echo \u89e3\u7801\nsr, x = wav.read('audio.wav')\nsig = x[:, 0].astype(np.float32)\nd0, d1, ws = 100, 130, 2205\nbits = []\nfor off in range(0, len(sig) - ws + 1, ws):\n    seg = sig[off:off+ws]\n    cep = np.fft.irfft(np.log(np.abs(np.fft.rfft(seg))**2 + 1e-10))\n    p0 = max(cep[d0-2:d0+3]); p1 = max(cep[d1-2:d1+3])\n    bits.append(0 if p0 > p1 else 1)\n\nby = bytes(int(''.join(map(str, bits[i*8:(i+1)*8])), 2)\n           for i in range(len(bits)\/\/8))\nmorse_text = by[:74].decode()\n\nMORSE = {  # \u7701\u7565\uff0c\u540c\u6b63\u6587\n    '.-':'A','-...':'B', ...\n}\nplain = ''.join(MORSE[g] for g in morse_text.split())\nprint(f'ISCC{{{plain}}}')<\/code><\/pre>\n\n\n\n
                \n\n\n\n
                \u603b\u7ed3 \/ \u8e29\u5751<\/h4>\n\n\n\n
                  \n
                1. \u9898\u9762\u5173\u952e\u8bcd<\/strong>\uff1a\"\u56de\u54cd\"<\/code> + \"\u91cd\u590d\u64ad\u653e\u7684\u97f3\u4e50\"<\/code> \u2248 Echo Hiding<\/strong>\uff0c\u4e2d\u6587\u9898\u76ee\u5728\u6697\u793a\u800c\u975e\u88c5\u9970\u3002<\/li>\n\n\n\n
                2. \u5012\u8c31\u662f echo hiding \u7684\u6807\u914d\u7834\u6cd5<\/strong>\uff1a\u4e00\u6b21 FFT + log + IFFT \u5c31\u80fd\u5b9a\u4f4d\u53cc\u5ef6\u8fdf\uff0c\u4e0d\u9700\u8981\u673a\u5668\u5b66\u4e60\uff0c\u4e5f\u4e0d\u9700\u8981\u5df2\u77e5\u660e\u6587\u3002<\/li>\n\n\n\n
                3. \u7ea2\u9cb1\u9c7c\u62c9\u6ee1<\/strong>\uff1a2.7 MB \u7684 SEI \u9644\u52a0\u6570\u636e\u3001\u770b\u4f3c”\u85cf\u5b57”\u7684\u5730\u677f\u3001\u955c\u9762\u5bf9\u79f0\uff0c\u90fd\u662f 40-50% \u8017\u65f6\u7684\u9677\u9631\u3002\u575a\u4fe1\u5bc6\u94a5\u4fe1\u606f\u5bc6\u5ea6<\/strong> \u2014\u2014\u771f\u6b63\u7684 payload \u53ea\u6709 74 \u5b57\u8282\u3002<\/li>\n\n\n\n
                4. \u7a97\u5bbd\u8981\u626b<\/strong>\uff1aws<\/code> \u51b3\u5b9a\u6bd4\u7279\u7387\uff0c\u6ca1\u63d0\u793a\u65f6\u4ece 1024 \u8d77\u6b65 2\u00d7 \u7ffb\u500d\u626b\uff0c\u627e\u5230 “\u524d N \u5b57\u8282\u5168\u53ef\u6253\u5370 ASCII” \u7684\u90a3\u4e00\u6863\u3002<\/li>\n\n\n\n
                5. Morse \u8981\u5e26\u6807\u70b9<\/strong>\uff1a.-.-.<\/code> = +<\/code>\u3001..--..<\/code> = ?<\/code> \u8fd9\u4e9b\u4e0d\u5728\u7eaf\u5b57\u6bcd\u8868\u91cc\uff0c\u9700\u8981\u7528 ITU-R M.1677 \u5b8c\u6574\u8868\u3002<\/li>\n<\/ol>\n\n\n\n
                  misc3<\/h3>\n\n\n\n
                  \n
                  \u8fd9\u4e2a\u9898\u4e00\u76f40\u89e3\uff0c\u6700\u540e\u7ed9\u4e86\u63d0\u793a\u505a\u51fa\u67651\u4e2a\uff0c\u63a5\u7740\u5982\u75c5\u6bd2\u6269\u6563\u4e00\u6837\u5168\u90fd\u505a\u51fa\u6765\u4e86\uff0c\u4e00\u4e2a\u6587\u5b57\u6e38\u620f\u9898\u3002\u6709\u70b9\u6076\u5fc3\uff0c\u627e\u4e0d\u5230\u9644\u4ef6\u4e86\uff0c\u6545\u800c\u6ca1\u6709\u590d\u73b0\uff0c\u5927\u81f4\u6d41\u7a0b\u5982\u4e0b<\/p>\n<\/blockquote>\n\n\n\n
                  \"\"\/<\/div><\/figure>\n\n\n\n
                  \u590d\u8d5b<\/h2>\n\n\n\n
                  \n
                  \u5b66\u6821\u8fdb5\u4e2a\u7ed9\u7ecf\u8d39\u652f\u6301\uff0c\u672c\u4eba\u7531\u4e8e\u4e94\u4e00\u5728\u800d\u6700\u540e\u51e0\u4e2a\u5c0f\u65f6\u770bwp\u53ea\u4ea4\u4e86\u51e0\u4e2a\uff0c\u6709\u5e78\u7b2c\u516d\u540d\uff0c\u56e0\u6b64\u5728\u8fd9\u4e2a\u4ea4\u4e86198\u7684\u6bd4\u8d5b\u91cc\u9762\u6709\u5e78\u966a\u8dd1\u3002\u7b2c\u4e00\u5929\u4e0a\u5348\u4ee5\u6765\u5c31\u670d\u52a1\u5668\u5361\u7206\u662f\u771f\u7684\u6ca1\u8bdd\u8bb2\uff0c\u4e00\u5f00\u59cb\u6240\u6709wp\u90fd\u51fa\u6765\u4e86\uff0c\u5c31\u770b\u8c01\u5148\u5237\u65b0\u51fa\u9898\uff0c\u8fd9\u4e2a\u6bd4\u8d5b\u542b\u91d1\u91cf\u8fd8\u5728\u4e0d\u65ad\u4e0a\u5347<\/p>\n<\/blockquote>\n\n\n\n
                  misc1<\/h3>\n\n\n\n
                  \"\"\/<\/div><\/figure>\n\n\n\n
                  \u6b65\u9aa4\u4e00\uff1a\u6d41\u91cf\u6982\u89c8<\/p>\n\n\n\n
                  \u7528 scapy \u5206\u6790 pcapng \u6587\u4ef6\uff0c\u5171 1509 \u4e2a\u6570\u636e\u5305\uff1a<\/p>\n\n\n\n
                  \u6765\u6e90 IP<\/th>\u76ee\u6807 IP<\/th>\u534f\u8bae<\/th>\u6570\u91cf<\/th><\/tr><\/thead>
                  192.168.1.100<\/td>239.255.255.250<\/td>UDP<\/td>1500<\/td><\/tr>
                  192.168.1.100<\/td>45.78.1.1<\/td>TCP<\/td>9<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                    \n
                  • 1500 \u4e2a UDP \u7ec4\u64ad\u5305<\/strong> \u2192 “\u58f0\u4e1c”\uff08\u4f6f\u653b\/\u55a7\u56a3\uff09<\/li>\n\n\n\n
                  • 9 \u4e2a TCP \u5305<\/strong> \u2192 “\u51fb\u897f”\uff08\u771f\u6b63\u7684\u653b\u51fb\uff09<\/li>\n<\/ul>\n\n\n\n
                    \u6b65\u9aa4\u4e8c\uff1a\u7ec4\u64ad\u6d41\u91cf\u4e2d\u7684\u94a5\u5319<\/p>\n\n\n\n
                    UDP \u7ec4\u64ad\u5305\u7684\u76ee\u6807\u7aef\u53e3\u4e3a 1900\uff08SSDP\uff09\uff0c\u6bcf\u4e2a\u5305\u643a\u5e26 28 \u5b57\u8282 Base64 \u8f7d\u8377\u30021497 \u4e2a\u552f\u4e00\u8f7d\u8377\u4e2d\uff0c\u6709\u4e00\u4e2a\u51fa\u73b0\u4e86 4 \u6b21<\/strong>\uff1a<\/p>\n\n\n\n
                    U2hlbmdEb25nSmlYaUAzNi0xLTY=<\/code><\/pre>\n\n\n\n
                    Base64 \u89e3\u7801\u5f97\u5230\uff1a<\/p>\n\n\n\n
                    ShengDongJiXi@36-1-6<\/code><\/pre>\n\n\n\n
                    \u5373”\u58f0\u4e1c\u51fb\u897f@36-1-6″\uff08\u4e09\u5341\u516d\u8ba1\u7b2c\u4e00\u5957\u7b2c\u516d\u8ba1\uff09\u3002\u8fd9\u65e2\u662f\u63d0\u793a\uff0c\u4e5f\u662f\u540e\u7eed\u89e3\u5bc6\u7684\u5bc6\u7801<\/strong>\u3002<\/p>\n\n\n\n
                    \u6b65\u9aa4\u4e09\uff1aTCP \u6d41\u91cf\u4e2d\u7684\u771f\u6b63\u6307\u4ee4<\/p>\n\n\n\n
                    9 \u4e2a TCP \u5305\u662f 192.168.1.100:12345 \u2194 45.78.1.1:80 \u7684 HTTP \u901a\u4fe1\u3002\u5176\u4e2d\u7b2c 4 \u4e2a\u5305\uff08PSH+ACK\uff09\u643a\u5e26 HTTP POST \u8bf7\u6c42\uff1a<\/p>\n\n\n\n
                    POST \/command HTTP\/1.1\nHost: 45.78.1.1\nContent-Type: application\/json\nContent-Length: 680\n\n{\"instruction\": \"<Base64>\", \"note\": \"This is the real command.\"}<\/code><\/pre>\n\n\n\n
                    instruction<\/code> \u5b57\u6bb5\u662f\u4e00\u957f\u4e32 Base64\uff0c\u89e3\u7801\u540e\u4ee5 PK\\x03\\x04<\/code> \u5f00\u5934\u2014\u2014\u8fd9\u662f\u4e00\u4e2a ZIP \u6587\u4ef6<\/strong>\u3002<\/p>\n\n\n\n
                    \u6b65\u9aa4\u56db\uff1a\u89e3\u5bc6 ZIP<\/p>\n\n\n\n
                    ZIP \u4f7f\u7528 AES-128 \u52a0\u5bc6<\/strong>\uff08compression method 99\uff09\uff0c\u5bc6\u7801\u6b63\u662f\u7ec4\u64ad\u6d41\u91cf\u4e2d\u63d0\u53d6\u7684\uff1a<\/p>\n\n\n\n
                    ShengDongJiXi@36-1-6<\/code><\/pre>\n\n\n\n
                    \u89e3\u538b\u5f97\u5230\u4e00\u5f20 100\u00d7100 \u50cf\u7d20\u7684 RGB PNG \u56fe\u7247 image.png<\/code>\u3002<\/p>\n\n\n\n
                    \u6b65\u9aa4\u4e94\uff1aLSB \u9690\u5199\u63d0\u53d6 Flag<\/p>\n\n\n\n
                    PNG \u56fe\u7247\u770b\u4f3c\u7eaf\u8272\uff08\u7070\u84dd\u8272\uff09\uff0c\u4f46\u50cf\u7d20\u503c\u5728\u5fae\u5c0f\u8303\u56f4\u5185\u6ce2\u52a8\uff1a<\/p>\n\n\n\n
                      \n
                    • R \u2208 {72, 73}<\/li>\n\n\n\n
                    • G \u2208 {108, 109}<\/li>\n\n\n\n
                    • B \u2208 {136, 137}<\/li>\n<\/ul>\n\n\n\n
                      \u6bcf\u4e2a\u901a\u9053\u53ea\u6709\u4e24\u4e2a\u53ef\u80fd\u503c\uff0c\u5dee\u503c\u6070\u597d\u4e3a 1\u3002\u8fd9\u662f\u5178\u578b\u7684 LSB\uff08\u6700\u4f4e\u6709\u6548\u4f4d\uff09\u9690\u5199<\/strong>\uff1a\u6bcf\u4e2a\u50cf\u7d20\u7684\u6bcf\u4e2a\u989c\u8272\u901a\u9053\u7684 LSB \u7f16\u7801 1 bit \u4fe1\u606f\u3002<\/p>\n\n\n\n
                      \u63d0\u53d6\u65b9\u6cd5\uff1a\u904d\u5386\u6240\u6709\u50cf\u7d20\uff0c\u6309 RGB \u4ea4\u9519\u987a\u5e8f\u8bfb\u53d6\u6bcf\u4e2a\u901a\u9053\u7684 LSB\uff0c\u6bcf 8 \u4f4d\u8f6c\u6362\u4e3a\u4e00\u4e2a ASCII \u5b57\u7b26\u3002<\/p>\n\n\n\n
                      from PIL import Image\n\nimg = Image.open(\"image.png\")\npx = img.load()\n\nbits = ''\nfor y in range(100):\n    for x in range(100):\n        r, g, b = px[x, y]\n        bits += str(r & 1) + str(g & 1) + str(b & 1)\n\nflag = ''\nfor i in range(0, len(bits) - 7, 8):\n    flag += chr(int(bits[i:i+8], 2))<\/code><\/pre>\n\n\n\n
                      ISCC{1d3f1c44t10n_1s4_th3_k3y_t0_v1cmtc0Fry}<\/code><\/pre>\n\n\n\n
                      <\/h4>\n\n\n\n
                      \u603b\u7ed3<\/p>\n\n\n\n
                      \u9636\u6bb5<\/th>\u6280\u672f<\/th>\u8bf4\u660e<\/th><\/tr><\/thead>
                      \u6d41\u91cf\u5206\u6790<\/td>Scapy<\/td>\u5206\u79bb\u7ec4\u64ad\u566a\u58f0\u4e0e TCP \u771f\u5b9e\u901a\u4fe1<\/td><\/tr>
                      \u5bc6\u94a5\u53d1\u73b0<\/td>Base64 \u89e3\u7801<\/td>\u7ec4\u64ad\u8f7d\u8377\u4e2d\u91cd\u590d\u51fa\u73b0\u7684\u5bc6\u7801<\/td><\/tr>
                      \u6570\u636e\u63d0\u53d6<\/td>ZIP AES-128<\/td>\u4ece TCP \u8f7d\u8377 Base64 \u4e2d\u8fd8\u539f\u52a0\u5bc6 ZIP<\/td><\/tr>
                      \u9690\u5199\u89e3\u7801<\/td>LSB \u9690\u5199<\/td>\u4ece PNG \u50cf\u7d20\u6700\u4f4e\u4f4d\u63d0\u53d6 Flag<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                      \u4e09\u5341\u516d\u8ba1”\u58f0\u4e1c\u51fb\u897f”\u8d2f\u7a7f\u5168\u9898\uff1a\u7ec4\u64ad\u6d41\u91cf\u662f”\u58f0\u4e1c”\uff08\u4f6f\u653b\uff09\uff0cTCP HTTP \u8bf7\u6c42\u662f”\u51fb\u897f”\uff08\u5b9e\u653b\uff09\uff1b\u7ec4\u64ad\u4e2d\u7684 Base64 \u5b57\u7b26\u4e32\u662f\u6253\u5f00 ZIP \u7684\u94a5\u5319\uff0c\u800c ZIP \u5185\u7684 PNG \u53c8\u901a\u8fc7 LSB \u9690\u5199\u85cf\u533f\u4e86\u6700\u7ec8\u7684 Flag\u3002<\/p>\n\n\n\n
                      misc2<\/h3>\n\n\n\n
                      \"\"\/<\/div><\/figure>\n\n\n\n
                      \u7ed9\u4e86\u4e00\u4e2a\u52a0\u5bc6\u538b\u7f29\u5305\u548c21\u4e2a\u6709\u7f16\u53f7\u7684png\uff0c\u6bcf\u4e2aPNG\u662f\u6761\u5f62\u7801\uff0c\u53ef\u4ee5\u8bfb\u53d6\u6240\u6709\u7684\u503c\u3002\u53e6\u5916LSB\u5b58\u5728\u7ea2\u8272\u901a\u9053\u9690\u5199\uff0c\u6bcf\u4e2a\u56fe\u7247\u8fd8\u6709Comment\uff0c\u63d0\u53d6\u8fd9\u4e9b\u6570\u636e<\/p>\n\n\n\n
                      from PIL import Image\nimport os\nimport struct\n\nbase = r'C:\\Users\\q1388\\Downloads\\attachment-18'\n\ndef extract_lsb_red_clean(img_path):\n    \"\"\"Extract LSB of red channel, try all 8 bit offsets to find clean readable data.\"\"\"\n    img = Image.open(img_path).convert('RGB')\n    pixels = list(img.getdata())\n\n    # Extract red channel LSB bits\n    bits = []\n    for p in pixels:\n        bits.append(p[0] & 1)\n\n    best_results = []\n    for offset in range(8):\n        byte_chars = []\n        for i in range(offset, len(bits) - 7, 8):\n            byte = 0\n            for j in range(8):\n                byte = (byte << 1) | bits[i + j]\n            byte_chars.append(byte)\n        # Look for the longest printable segment\n        segs = []\n        current = []\n        for b in byte_chars:\n            if 32 <= b < 127:\n                current.append(chr(b))\n            else:\n                if current:\n                    segs.append(''.join(current))\n                    current = []\n        if current:\n            segs.append(''.join(current))\n        best_results.append((offset, segs))\n    return best_results\n\ndef extract_lsb_raw_message(img_path):\n    \"\"\"Try to extract LSB as a contiguous hidden message using all red pixels.\"\"\"\n    img = Image.open(img_path).convert('RGB')\n    pixels = list(img.getdata())\n\n    # Red LSB bits in order\n    bits = []\n    for p in pixels:\n        bits.append(p[0] & 1)\n\n    # Try each bit offset 0-7 to get clean byte alignment\n    results = {}\n    for offset in range(8):\n        raw_bytes = []\n        for i in range(offset, len(bits) - 7, 8):\n            byte = 0\n            for j in range(8):\n                byte = (byte << 1) | bits[i + j]\n            raw_bytes.append(byte)\n        results[offset] = bytes(raw_bytes)\n    return results\n\n# PNG comments\ndef get_comments(filepath):\n    with open(filepath, 'rb') as f:\n        f.read(8)  # sig\n        comments = []\n        while True:\n            lb = f.read(4)\n            if len(lb) < 4: break\n            length = struct.unpack('>I', lb)[0]\n            ctype = f.read(4)\n            data = f.read(length) if length > 0 else b''\n            f.read(4)  # crc\n            if ctype == b'IEND': break\n            if ctype == b'tEXt':\n                null = data.find(b'\\x00')\n                if null >= 0:\n                    kw = data[:null].decode('latin-1')\n                    txt = data[null+1:].decode('latin-1')\n                    comments.append((kw, txt))\n        return comments\n\nprint(\"=\" * 80)\nprint(\"COMPLETE EXTRACTION \u2014 BARCODE \/ LSB RED \/ COMMENT\")\nprint(\"=\" * 80)\n\nall_lsb = []\nall_comments = []\nall_barcodes = []\n\nfor i in range(21):\n    fname = f'barcode_{i:02d}.png'\n    path = os.path.join(base, fname)\n    print(f\"\\n{'\u2500'*60}\")\n    print(f\"[{i:02d}] {fname}\")\n\n    # Barcode\n    from pyzbar.pyzbar import decode as zbar_decode\n    decoded = zbar_decode(Image.open(path))\n    barcode_data = decoded[0].data.decode('utf-8') if decoded else '(none)'\n    all_barcodes.append(barcode_data)\n    print(f\"    Barcode : {barcode_data}\")\n\n    # Comment\n    comments = get_comments(path)\n    comment_str = comments[0][1] if comments else '(none)'\n    all_comments.append(comment_str)\n    print(f\"    Comment : {comment_str}\")\n\n    # LSB red \u2014 find the best offset with longest readable segment\n    raw_msgs = extract_lsb_raw_message(path)\n    # Usually the \"real\" hidden message starts right at the first pixel\n    # Try offset by reading first few bytes at each offset\n    best = \"\"\n    for off in range(8):\n        data = raw_msgs[off]\n        # Find longest printable segment\n        printable = bytearray()\n        for b in data:\n            if 32 <= b < 127:\n                printable.append(b)\n            elif len(printable) > 3:\n                break  # end of segment\n            else:\n                printable = bytearray()  # reset\n        candidate = printable.decode('ascii', errors='replace')\n        if len(candidate) > len(best):\n            best = candidate\n\n    # Also try the very first 8 chars from offset 0\n    # The typical steganography puts the message starting at pixel 0\n    first_bytes = raw_msgs[0]\n    raw_printable = ''.join(chr(b) if 32 <= b < 127 else '.' for b in first_bytes[:50])\n\n    all_lsb.append(best if best else raw_printable[:20])\n    print(f\"    LSB Red : {best if best else '(no clean segment found)'}\")\n    print(f\"    LSB (raw first 50 bytes): {raw_printable}\")\n\n# Summary\nprint(f\"\\n{'='*80}\")\nprint(\"SUMMARY TABLE\")\nprint(f\"{'='*80}\")\nprint(f\"{'#':>3}  {'Barcode':<12} {'LSB Red':<16} {'Comment':<12}\")\nprint(f\"{'\u2500'*3}  {'\u2500'*12} {'\u2500'*16} {'\u2500'*12}\")\nfor i in range(21):\n    print(f\"{i:>3}  {all_barcodes[i]:<12} {all_lsb[i]:<16} {all_comments[i]:<12}\")\n\n# Look for patterns\nprint(f\"\\n{'='*80}\")\nprint(\"CONCATENATED DATA (all LSB messages combined):\")\nprint(f\"{'='*80}\")\nprint(''.join(all_lsb))\n\nprint(f\"\\nAll Comments concatenated:\")\n\n\nprint(''.join(all_comments))\n\n# Check if barcodes form a pattern when concatenated\nprint(f\"\\nAll Barcodes concatenated:\")\nprint(''.join(all_barcodes))\n\n\n  \u250c\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\n  \u2502  #  \u2502 Barcode  \u2502 LSB Red  \u2502 Comment  \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 00  \u2502 J03a03fJ \u2502 ezI4WEt3 \u2502 rnQZDgzm \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 01  \u2502 zbnFJazb \u2502 plDre1U2 \u2502 A1fd57fA \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 02  \u2502 P}1LZrPm \u2502 H000100H \u2502 MNSKk6qD \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 03  \u2502 dWtNaXR9 \u2502 M1bf54bM \u2502 iPjJGRXX \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 04  \u2502 zCUS3K8x \u2502 T1057d1T \u2502 M3F2QUV9 \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 05  \u2502 P1041a7P \u2502 LKE6JRrm \u2502 RmxhZz0= \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 06  \u2502 zybUNbYS \u2502 hj8W6pWE \u2502 N001ab1N \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 07  \u2502 RGZuNVl9 \u2502 lTD4YoV8 \u2502 G1fd57fG \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 08  \u2502 RmxhZz0= \u2502 C17595dC \u2502 F4tcgeVU \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 09  \u2502 ezM3anlz \u2502 R1758b2R \u2502 xLTGj7W8 \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 10  \u2502 SGw4NTB9 \u2502 0UCxLxzR \u2502 F104e41F \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 11  \u2502 RmxhZz0= \u2502 CNxSHPv6 \u2502 L1a0f20L \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 12  \u2502 aW5ub3Rl \u2502 iJVzvtdg \u2502 B104641B \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 13  \u2502 tNMZvoRm \u2502 I1e5f9dI \u2502 NNEaGhzh \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 14  \u2502 RmxhZz0= \u2502 S175bccS \u2502 AIfO30BL \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 15  \u2502 DQJv0Hrw \u2502 e0dCWTlR \u2502 K1470e5K \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 16  \u2502 E17515dE \u2502 ldd}S9UB \u2502 m5qEHfnr \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 17  \u2502 TmJCUDh9 \u2502 4bpuUs2l \u2502 D175b5dD \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 18  \u2502 Q1749e6Q \u2502 pH}Uf7gn \u2502 LPKxr9tg \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 19  \u2502 zqptXF0J \u2502 3lvCqkRW \u2502 O1fca70O \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 20  \u2502 OBhdxqpx \u2502 QdX4GOwN \u2502 U1fd51cU \u2502\n  \u2514\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/code><\/pre>\n\n\n\n
                      \u4e09\u5c42\u4fe1\u606f\u4e2d\uff0c\u6709\u4e00\u5c42\u4f1a\u5339\u914d AxxxxxxA \u5230 UxxxxxxU\uff0c\u5206\u522b\u63d0\u53d6<\/p>\n\n\n\n
                        \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u252c\u2500\u2500\u2500\u2500\u2500\u2500\u2510\n  \u2502 \u5b57\u6bcd  \u2502    \u503c    \u2502 \u6240\u5728\u5217  \u2502 \u884c\u53f7 \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 A    \u2502 A1fd57fA \u2502 Comment \u2502 01   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 B    \u2502 B104641B \u2502 Comment \u2502 12   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 C    \u2502 C17595dC \u2502 LSB Red \u2502 08   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 D    \u2502 D175b5dD \u2502 Comment \u2502 17   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 E    \u2502 E17515dE \u2502 Barcode \u2502 16   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 F    \u2502 F104e41F \u2502 Comment \u2502 10   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 G    \u2502 G1fd57fG \u2502 Comment \u2502 07   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 H    \u2502 H000100H \u2502 LSB Red \u2502 02   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 I    \u2502 I1e5f9dI \u2502 LSB Red \u2502 13   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 J    \u2502 J03a03fJ \u2502 Barcode \u2502 00   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 K    \u2502 K1470e5K \u2502 Comment \u2502 15   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 L    \u2502 L1a0f20L \u2502 Comment \u2502 11   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 M    \u2502 M1bf54bM \u2502 LSB Red \u2502 03   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 N    \u2502 N001ab1N \u2502 Comment \u2502 06   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 O    \u2502 O1fca70O \u2502 Comment \u2502 19   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 P    \u2502 P1041a7P \u2502 Barcode \u2502 05   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 Q    \u2502 Q1749e6Q \u2502 Barcode \u2502 18   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 R    \u2502 R1758b2R \u2502 LSB Red \u2502 09   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 S    \u2502 S175bccS \u2502 LSB Red \u2502 14   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 T    \u2502 T1057d1T \u2502 LSB Red \u2502 04   \u2502\n  \u251c\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u253c\u2500\u2500\u2500\u2500\u2500\u2500\u2524\n  \u2502 U    \u2502 U1fd51cU \u2502 Comment \u2502 20   \u2502\n  \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2534\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/code><\/pre>\n\n\n\n
                      \u8fd9\u91cc\u4e00\u5171\u6709 21 \u7ec4\u6570\u636e\uff0c\u7f16\u53f7\u4e3a A \u5230 U \uff0c\u521a\u597d\u662f 21 \u884c\u3002\u6bcf\u7ec4\u6570\u636e\u662f 6 \u4f4d\u5341\u516d\u8fdb\u5236\uff0c\u5373 24 bit\u3002\u800c QR Code version 1 \u7684\u5c3a\u5bf8\u662f 21 x 21 \u3002\u56e0\u6b64\u53ef\u4ee5\u5c06\u6bcf\u7ec4\u5341\u516d\u8fdb\u5236\u8f6c\u6210 24 \u4f4d\u4e8c\u8fdb\u5236\uff0c\u7136\u540e\u6bcf\u884c\u4e22\u6389\u524d 3 bit\uff0c\u4fdd\u7559\u540e 21 bit\uff0c\u62fc\u6210\u4e00\u4e2a 21 x 21 \u7684\u4e8c\u7ef4\u7801\u77e9\u9635\u3002<\/p>\n\n\n\n
                      from PIL import Image\nimport zxingcpp\nrows = {\n      \"A\": \"1fd57f\", \"B\": \"104641\", \"C\": \"17595d\", \"D\": \"175b5d\",\n      \"E\": \"17515d\", \"F\": \"104e41\", \"G\": \"1fd57f\", \"H\": \"000100\",\n      \"I\": \"1e5f9d\", \"J\": \"03a03f\", \"K\": \"1470e5\", \"L\": \"1a0f20\",\n      \"M\": \"1bf54b\", \"N\": \"001ab1\", \"O\": \"1fca70\", \"P\": \"1041a7\",\n      \"Q\": \"1749e6\", \"R\": \"1758b2\", \"S\": \"175bcc\", \"T\": \"1057d1\",\n      \"U\": \"1fd51c\",\n  }\norder = \"ABCDEFGHIJKLMNOPQRSTU\"\nscale = 10\nquiet = 4\nqr = Image.new(\"RGB\", ((21 + 2 * quiet) * scale, (21 + 2 * quiet) * scale),\n\"white\")\nfor y, ch in enumerate(order):\n    bits = f\"{int(rows[ch], 16):024b}\"[3:] # \u4fdd\u7559\u540e 21 bit\n    for x, b in enumerate(bits):\n        if b == \"1\":\n            for yy in range((y + quiet) * scale, (y + quiet + 1) * scale):\n                for xx in range((x + quiet) * scale, (x + quiet + 1) * scale):\n                    qr.putpixel((xx, yy), (0, 0, 0))\nqr.save(\"qr.png\")\nprint(zxingcpp.read_barcodes(qr)[0].text)<\/code><\/pre>\n\n\n\n
                      \u5f97\u5230\u4e8c\u7ef4\u7801<\/p>\n\n\n\n
                      \"\"\/<\/div><\/figure>\n\n\n\n
                      \u5f97\u5230<\/p>\n\n\n\n
                      M741rTwaoSZLCov<\/code><\/pre>\n\n\n\n
                      \u8fd9\u4e2a\u5bc6\u7801\u53ef\u4ee5\u6253\u5f00\u538b\u7f29\u5305\uff0c\u5f97\u5230\u4e00\u4e2apdf<\/p>\n\n\n\n
                      \u76f4\u63a5\u67e5\u770b PDF \u8868\u9762\u5185\u5bb9\u53ea\u662f\u4e00\u5f20\u4e50\u8c31\uff0c\u4f46\u7528 PyMuPDF \u63d0\u53d6\u6587\u672c\u53ef\u4ee5\u53d1\u73b0\u9690\u85cf\u6587\u5b57\uff1a<\/p>\n\n\n\n
                      import fitz\ndoc = fitz.open(\"score_extract\/music score.pdf\")\nprint(doc[0].get_text())<\/code><\/pre>\n\n\n\n
                      \u8f93\u51fa\uff1a<\/p>\n\n\n\n
                      KEY+bnVtYmVyYWJvdmVsaW5l3\n\n\n\n\u53e6\u5916base64\u89e3\u7801\uff1a\nKEY + number above line 3<\/code><\/pre>\n\n\n\n
                      number above line 3 \u8868\u793a\u53d6\u7b2c\u4e09\u884c\u4e94\u7ebf\u8c31\u4e0a\u65b9\u7684\u6570\u5b57\u3002\u89c2\u5bdf PDF \u7b2c\u4e09\u884c\uff0c\u8c31\u7ebf\u4e0a\u65b9\u7684\u6570\u5b57\u4f9d\u6b21\u4e3a\uff1a<\/p>\n\n\n\n
                      4 1 5 1 5 1 5<\/code><\/pre>\n\n\n\n
                      \u6240\u4ee5flag\u662f\u538b\u7f29\u5305\u5bc6\u7801+4151515<\/p>\n\n\n\n
                      ISCC{M741rTwaoSZLCov4151515}<\/code><\/pre>\n\n\n\n
                      \u64c2\u53f0\u8d5b-misc<\/h3>\n\n\n\n
                      \"\"\/<\/div><\/figure>\n\n\n\n
                      \u9898\u76ee\u63cf\u8ff0<\/h4>\n\n\n\n
                      \u9644\u4ef6 showtime_01.zip<\/code> \u89e3\u538b\u540e\u5f97\u5230 challenge.txt<\/code>\uff0c\u8868\u9762\u662f\u4e00\u6bb5\u591a\u8bed\u8a00\u6587\u672c\uff0c\u5185\u90e8\u5939\u6742\u5927\u91cf\u4e0d\u53ef\u89c1\u5b57\u7b26\u3002<\/p>\n\n\n\n
                      1. \u96f6\u5bbd\u5b57\u7b26\u63d0\u53d6\u4e0e\u7edf\u8ba1<\/h4>\n\n\n\n
                      \u8bfb\u53d6\u6587\u4ef6\uff0c\u63d0\u53d6\u96f6\u5bbd\u5b57\u7b26\uff1a<\/p>\n\n\n\n
                      \"\"\/<\/div><\/figure>\n\n\n\n
                      from pathlib import Path\nfrom collections import Counter\n\ns = Path(\"challenge.txt\").read_text(encoding=\"utf-8\")\n\nchars = [\"\u200b\", \"\u200c\", \"\u200d\", \"\ufeff\"]\nhidden = \"\".join(c for c in s if c in chars)\n\nprint(len(hidden))       # 2592\nprint(Counter(hidden))   # {'\u200b': 677, '\ufeff': 653, '\u200c': 640, '\u200d': 622}<\/code><\/pre>\n\n\n\n
                      \u5171 2592 \u4e2a\u96f6\u5bbd\u5b57\u7b26\uff0c4 \u79cd\u5b57\u7b26\u6570\u91cf\u63a5\u8fd1\uff0c\u521d\u6b65\u5224\u65ad\u6bcf\u5b57\u7b26\u7f16\u7801 2 bit\u3002<\/p>\n\n\n\n
                      2. \u96f6\u5bbd\u5b57\u7b26 \u2192 \u4e8c\u8fdb\u5236\u89e3\u7801<\/h4>\n\n\n\n
                      \u6309 Unicode \u7801\u70b9\u987a\u5e8f\u5efa\u7acb 2-bit \u6620\u5c04\uff1a<\/p>\n\n\n\n
                      \u5b57\u7b26<\/th>Unicode<\/th>\u6620\u5c04<\/th><\/tr><\/thead>
                      U+200B<\/td>ZWSP<\/td>00<\/td><\/tr>
                      U+200C<\/td>ZWNJ<\/td>01<\/td><\/tr>
                      U+200D<\/td>ZWJ<\/td>10<\/td><\/tr>
                      U+FEFF<\/td>BOM<\/td>11<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
                      mapping = {\n    \"\u200b\": \"00\",\n    \"\u200c\": \"01\",\n    \"\u200d\": \"10\",\n    \"\ufeff\": \"11\",\n}\n\nbits = \"\".join(mapping[c] for c in s if c in mapping)\n\ndata = bytes(\n    int(bits[i:i+8], 2)\n    for i in range(0, len(bits), 8)\n)\n\nprint(data[:16].hex())  # 23f60579789c6593df4fdb3010c7ff95<\/code><\/pre>\n\n\n\n
                      \u8f93\u51fa\u5934\u90e8\u51fa\u73b0 78 9c<\/code>\uff08\u504f\u79fb 4 \u5904\uff09\uff0c\u8fd9\u662f zlib \u538b\u7f29\u6570\u636e<\/strong>\u7684\u6807\u8bc6\u3002<\/p>\n\n\n\n
                      3. zlib \u89e3\u538b<\/h4>\n\n\n\n
                      \u8df3\u8fc7\u524d 4 \u5b57\u8282\uff08\u53ef\u80fd\u662f\u957f\u5ea6\u524d\u7f00\uff09\u540e\u89e3\u538b\uff1a<\/p>\n\n\n\n
                      import zlib\n\npayload = zlib.decompress(data[4:])\nprint(payload.decode())<\/code><\/pre>\n\n\n\n
                      \u5f97\u5230 JSON\uff1a\uff08\u4ece\u8fd9\u91cc\u5f00\u59cb\u5c31\u662f\u4e00\u4e2a\u5bc6\u7801\u9898\uff09<\/p>\n\n\n\n
                      {\n  \"difficulty_bits\": 26,\n  \"nonce\": \"inst_000_42ba6c3fb9863dfa\",\n  \"encrypted_flag\": {\n    \"ciphertext\": \"aa228292d48f64709888c44ce7c331b04e486e566f573fef354370c5f166d8ae68e6556e9607e1da07bc79203c092372\",\n    \"iv\": \"5dc0b444e4ff507d4af8dcda8e64afa9\"\n  },\n  \"key_derivation\": {\n    \"algorithm\": \"PBKDF2-HMAC-SHA256\",\n    \"iterations\": 10000,\n    \"dklen\": 32,\n    \"password\": \"str(s) UTF-8\",\n    \"salt\": \"nonce UTF-8\"\n  },\n  \"aes\": {\n    \"algorithm\": \"AES-256-CBC\",\n    \"padding\": \"PKCS7\"\n  }\n}<\/code><\/pre>\n\n\n\n
                      4. PoW \u7206\u7834<\/h4>\n\n\n\n
                      \u6761\u4ef6\uff1aSHA256(nonce || str(s))<\/code> \u7684\u54c8\u5e0c\u503c\u81f3\u5c11 26 \u4e2a\u524d\u5bfc 0 bit\uff0c\u4ece s=0<\/code> \u5f00\u59cb\u9012\u589e\u627e\u6700\u5c0f\u6ee1\u8db3\u6761\u4ef6\u7684\u6574\u6570\u3002<\/p>\n\n\n\n
                      import hashlib\n\nnonce = b\"inst_000_42ba6c3fb9863dfa\"\ndifficulty_bits = 26\n\nfull = difficulty_bits \/\/ 8    # 3\nrem = difficulty_bits % 8      # 2\nmask = (0xff << (8 - rem)) & 0xff  # 0xc0\n\ns = 0\nwhile True:\n    h = hashlib.sha256(nonce + str(s).encode()).digest()\n    if h[:full] == b\"\\x00\" * full:          # \u524d 3 \u5b57\u8282\u5168 0\n        if rem == 0 or (h[full] & mask) == 0:  # \u7b2c 4 \u5b57\u8282\u9ad8 2 bit \u4e3a 0\n            print(s, h.hex())\n            break\n    s += 1<\/code><\/pre>\n\n\n\n
                      \u7ed3\u679c\uff1a<\/p>\n\n\n\n
                      s = 39235849\nhash = 0000003a61bb5cf11e82e63fdc3037f9e7dd85f46a26bc9b62f78b901f96f62e<\/code><\/pre>\n\n\n\n
                      \u524d 3 \u5b57\u8282 00 00 00<\/code>\uff0c\u7b2c 4 \u5b57\u8282 0x3a = 0b00111010<\/code>\uff0c\u9ad8 2 bit = 00<\/code>\uff0c\u6ee1\u8db3 26 \u4e2a\u524d\u5bfc\u96f6 bit\u3002<\/p>\n\n\n\n
                      5. AES \u89e3\u5bc6<\/h4>\n\n\n\n
                      \u4ee5 str(s)<\/code> \u4e3a PBKDF2 \u5bc6\u7801\u3001nonce \u4e3a\u76d0\u300110000 \u6b21\u8fed\u4ee3\u6d3e\u751f 32 \u5b57\u8282 AES-256 \u5bc6\u94a5\uff0cCBC \u6a21\u5f0f + PKCS7 \u586b\u5145\u89e3\u5bc6\uff1a<\/p>\n\n\n\n
                      import hashlib\nfrom Crypto.Cipher import AES\nfrom Crypto.Util.Padding import unpad\n\ns = \"39235849\"\nnonce = b\"inst_000_42ba6c3fb9863dfa\"\n\nct = bytes.fromhex(\"aa228292d48f64709888c44ce7c331b04e486e566f573fef354370c5f166d8ae68e6556e9607e1da07bc79203c092372\")\niv = bytes.fromhex(\"5dc0b444e4ff507d4af8dcda8e64afa9\")\n\nkey = hashlib.pbkdf2_hmac(\"sha256\", s.encode(), nonce, 10000, dklen=32)\n\npt = AES.new(key, AES.MODE_CBC, iv).decrypt(ct)\nflag = unpad(pt, 16).decode()\n\nprint(flag)<\/code><\/pre>\n\n\n\n
                      Flag<\/h4>\n\n\n\n
                      ISCC{Eb0TOol7GZ0YEHI38VjhYjtofGDIRC}<\/code><\/pre>\n\n\n\n
                      \u89e3\u9898\u6458\u8981<\/h4>\n\n\n\n
                      \u6b65\u9aa4<\/th>\u6280\u672f<\/th>\u5173\u952e\u70b9<\/th><\/tr><\/thead>
                      \u9690\u5199\u63d0\u53d6<\/td>\u96f6\u5bbd\u5b57\u7b26<\/td>U+200B\/200C\/200D\/FEFF \u7f16\u7801 2-bit<\/td><\/tr>
                      \u6570\u636e\u89e3\u7801<\/td>zlib<\/td>\u8df3\u8fc7 4 \u5b57\u8282\u5934\u90e8\u540e\u89e3\u538b<\/td><\/tr>
                      PoW \u7206\u7834<\/td>SHA256<\/td>26 bits \u524d\u5bfc\u96f6\uff0cs=39235849<\/td><\/tr>
                      \u5bc6\u94a5\u6d3e\u751f<\/td>PBKDF2-HMAC-SHA256<\/td>10000 \u8fed\u4ee3\uff0c32 \u5b57\u8282 key<\/td><\/tr>
                      \u89e3\u5bc6<\/td>AES-256-CBC<\/td>PKCS7 unpadding<\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"
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