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Inside Viktor's vault you found a strange audio re...

作成日: 2026年5月8日

使用モデル GPT-5.5 Thinking by Chat01

質問

vault_contents.zip

Inside Viktor's vault you found a strange audio recording and a binary catalogue. He was trying to decode something. Finish his work.

N.B.: flag format : THCON{...}

solve challenge

思考

bash -lc python3 - <<'PY' from pathlib import Path import struct,collections b=Path('/mnt/data/vault_contents/sigdb').read_bytes() records=[struct.unpack('<5H', b[i:i+10]) for i in range(0,len(b),10)] pairs=[(20,21),(24,25),(28,29),(30,31)] for pair in pairs: for cond in ['p01','p10','anyadj']: if cond=='p01': ms=[r for r in records if r[0]==pair[0] and r[1]==pair[1]] elif cond=='p10': ms=[r for r in records if r[0]==pair[1] and r[1]==pair[0]] else: ms=[r for r in records if set(r[:2])==set(pair)] print(pair, cond, len(ms), ms[:20]) print()

count matches exact pairs for all observed

obs=[20,21,24,25,28,29,30,31,44,45,54,55,56,57,58,59,68,69,70,71,74,75,78,79,80,81,84,85,86,87,114,115,120,121,122,123,132,133,136,137,142,143,148,149,152,153,154,155,160,161,164,165,166,167,176,177,182,183,188,189] for i in range(0,len(obs),2): ms=[r for r in records if r[0]==obs[i] and r[1]==obs[i+1]] chars=collections.Counter(chr(r[4]) for r in ms) print(i//2, (obs[i],obs[i+1]), len(ms), chars.most_common(5), sorted(set((r[2],r[3]) for r in ms))[:5]) PY

Thought for 3m 16s

回答

Solved.

The flag.txt was a breadcrumb/decoy:

THCON{h0p3_y0u_gr4bb3d_c0ff33_f0r_th3_n3xt_st3p}

The real path was:

  1. README_DIMITRI.txt hints at Wang’s paper, meaning Shazam-style spectral peak fingerprints.
  2. intercept.wav contains short pure-tone bursts.
  3. The tones land exactly on FFT bins, in adjacent pairs:
text
20,21  24,25  28,29  30,31  44,45  ...
  1. sigdb is a binary signature catalogue of 10-byte records:
text
uint16 freq1
uint16 freq2
uint16 something/index
uint16 something/index
uint16 ascii_char
  1. Matching each adjacent tone pair against the catalogue and reading the final ASCII field gives:
text
THCON{sp3ctr4l_p34ks_d0nt_l13}

Final flag:

text
THCON{sp3ctr4l_p34ks_d0nt_l13}

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