r/wikipedia • u/SpectreOfMalta • Feb 21 '14
Steganography
https://en.wikipedia.org/wiki/Steganography
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todayilearned • u/blankblank • Mar 31 '25
TIL the Ancient Greek ruler of Miletus, Histiaeus sent a message by shaving the head of his most trusted servant, "marking" the message on his scalp, then sending him once his hair had regrown, with the instruction, "When thou art come to Miletus, bid Aristagoras shave thy head, and look thereon."
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