crypto/mysterious-melody

mysterious-melody/chall.yaml

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+name: Mysterious Melody
+categories:
+  - misc
+  - crypto
+value: 100
+flag: bcactf{beautiful_melody_beautiful_harmony}
+# Alternatively:
+# flag:
+#   file: ./flag.txt
+# 
+description: |-
+  - We intercepted this mysterious melody being played on a secretive radio station. Can you figure out what it means?
+hints:
+  - base 16
+files:
+  - src: ./melody.wav
+authors:
+  - appllo
+visible: true

mysterious-melody/solve.txt

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+Each note in the melody corresponds to a hex digit from 0 to F,
+as indicated by the scale at the start of the sound file.
+
+Online tools exist to aid with music transcription, but another way
+is to view the spectrogram using a tool like Audacity.
+(Right click on track, select spectrogram view, and zoom into the right 
+frequencies. For convenience, right click and go into spectrogram settings
+and change scale to logarithmic to make the spacing better.)
+
+The correct note should now roughly line up with a bright spot in the
+spectrogram (and you can add horizontal lines in an image editor to
+aid with lining things up) and you can listen to the audio file to
+confirm that you are transcribing the correct one.
+
+Then, convert from hex to characters to retrieve the flag.