Letnja razbibriga... U čemu se razlikuju ove dve slike?
Za veći format, kliknite na sliku.
Napomena: nastaviće se. :)
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Pomoć broj 1 (23:20, 8. juli 2013.): Pogledajte tagove za ovaj tekst. Neki komentatori su već uočili koji metod je korišćen. :)
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Pomoć broj 2 (09:20, 9. juli 2013.): Korišćen je alat Steghide.
Steghide is a steganography program that is able to hide data in various kinds of image- and
audio-files. The color- respectivly sample-frequencies are not changed thus making the embedding
resistant against first-order statistical tests.
Evo i detalja:
steghide embed -ef Poruka_u_slici.txt -cf Koloseum1.jpg -sf Koloseum2.jpg -e rijndael-128 cbc -z 9
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Pomoć broj 3 (11:00, 9. juli 2013.):
steghide extract -sf Koloseum2.jpg -xf Poruka_izdvojena.txt
Trebaće Vam passphrase, a hint za nju je u komentarima.
Mislim da je ovo sasvim dovoljno za rešenje. :)
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Dejan je sinoć našao rešenje, ali nije objavio da ne kvari zabavu, a danas je rešenje otkrio i Uroš. Moram da pohvalim i loopinga koji je odmah u startu rekao stvar koja ide u pravom smeru i bio veoma blizu rešenja.
Čestitam!!!
Možda ćete se iznenaditi koliko teksta je stalo u jednu malu sliku korišćenjem steganografije, a da se to vizuelno skoro i ne primeti. Pri tome je slika sa tekstom i manja u kilobajtima nego original, jer je korišćena i kompresija.
Passphrase: blog.b92.net
Rešenje:
Sledeći tekst je skriven u slici Koloseum 2 metodom steganografije:
Steganografija - umetnost sakrivanja informacija
Steganografija je disciplina koja se bavi sakrivanjem poverljivih informacija u okviru nekih drugih, svima dostupnih informacija.
Reč steganografija potiče od grčkih reči steganos i graphein, što znači skriveno pisanje.
Za razliku od kriptografije čiji je cilj da podaci ne budu čitljivi svima, steganografija se bavi sakrivanjem informacija u neki drugi sadržaj.
Ova disciplina poznata je od davnina. Iz tog vremena datira jedna poznata steganografska metoda: nosiocu poruke se obrije glava, a onda se na nju utetovira poruka koju sakrije narasla kosa. Primalac jednostavno obrije glavu nosioca da bi došao do poruke. Ovom tehnikom su se koristili nemački špijuni početkom 20. veka.
Steganografska terminologija:
- Datoteka nosilac - Datoteka u kojoj će se nalaziti sakrivena informacija
- Stego-datoteka - Datoteka nosilac + skrivene informacije
- Redudantni bitovi - Bitovi koji mogu da posluže za sakrivanje informacije
- Stegoanaliza - Postupak otkrivanja informacija skrivenih u nekoj datoteci
Postoji mnogo načina na koje je moguće sakriti informaciju u okviru neke slike, audio ili video datoteke. Dve najkorišćenije metode su Injection i LSB (Last Significant Byte).
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Secrets of the Colosseum
A German archaeologist has finally deciphered the Roman amphitheater's amazing underground labyrinth
The floor of the colosseum, where you might expect to see a smooth ellipse of sand, is instead a bewildering array of masonry walls shaped in concentric rings, whorls and chambers, like a huge thumbprint. The confusion is compounded as you descend a long stairway at the eastern end of the stadium and enter ruins that were hidden beneath a wooden floor during the nearly five centuries the arena was in use, beginning with its inauguration in A.D. 80. Weeds grow waist-high between flagstones; caper and fig trees sprout from dank walls, which are a patchwork of travertine slabs, tufa blocks and brickwork. The walls and the floor bear numerous slots, grooves and abrasions, obviously made with great care, but for purposes that you can only guess.
The guesswork ends when you meet Heinz-Jürgen Beste of the German Archaeological Institute in Rome, the leading authority on the hypogeum, the extraordinary, long-neglected ruins beneath the Colosseum floor. Beste has spent much of the past 14 years deciphering the hypogeum-from the Greek word for "underground"-and this past September I stood with him in the heart of the great labyrinth.
"See where a semicircular slice has been chipped out of the wall?" he said, resting a hand on the brickwork. The groove, he added, created room for the four arms of a cross-shaped, vertical winch called a capstan, which men would push as they walked in a circle. The capstan post rested in a hole that Beste indicated with his toe. "A team of workmen at the capstan could raise a cage with a bear, leopard or lion inside into position just below the level of the arena. Nothing bigger than a lion would have fit." He pointed out a diagonal slot angling down from the top of the wall to where the cage would have hung. "A wooden ramp slid into that slot, allowing the animal to climb from the cage straight into the arena," he said.
Read more: http://www.smithsonianmag.com/history-archaeology/Secrets-of-the-Colosseum.html
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