Ofufuza aku Poland apereka njira yatsopano yolumikizira netiweki ya steganography pogwiritsa ntchito mawonekedwe a TCP omwe amagwiritsidwa ntchito kwambiri. Olemba ntchitoyo amakhulupirira kuti chiwembu chawo, mwachitsanzo, chingagwiritsidwe ntchito kutumiza mauthenga obisika m'mayiko opondereza omwe amakakamiza kufufuza kwambiri pa intaneti. Tiyeni tiyese kudziwa kuti lusoli ndi chiyani komanso kuti ndi lothandiza bwanji.
Choyamba, muyenera kufotokozera chomwe steganography ndi. Chifukwa chake, steganography ndi sayansi yakufalitsa uthenga wobisika. Ndiko kuti, pogwiritsa ntchito njira zake, maphwando akuyesera kubisala zenizeni za kusamutsa. Uku ndiko kusiyana pakati pa sayansi iyi ndi cryptography, yomwe imayesa pangitsa kuti uthengawo ukhale wosawerengeka. Ndizofunikira kudziwa kuti gulu la akatswiri a cryptographer limanyoza kwambiri steganography chifukwa cha kuyandikira kwa malingaliro ake ku mfundo ya "Chitetezo kudzera mumdima" (sindikudziwa momwe zimamvekera bwino mu Chirasha, monga "Chitetezo kudzera mu umbuli. β). Mfundo iyi, mwachitsanzo, imagwiritsidwa ntchito ndi Skype Inc. - gwero la woyimba wotchuka watsekedwa ndipo palibe amene akudziwa momwe deta imabisidwira. Posachedwapa, mwa njira, NSA inadandaula za izi, monga taonera katswiri wotchuka Bruce Schneier. pa blog yanga.
Kubwereranso ku steganography, tidzayankha funso: chifukwa chiyani kuli kofunikira ngati pali cryptography? Zowonadi, mutha kubisa uthenga pogwiritsa ntchito algorithm yamakono ndipo ngati mugwiritsa ntchito kiyi yayitali mokwanira, palibe amene azitha kuwerenga uthengawu pokhapokha mutaufuna. Komabe, nthawi zina zimakhala zothandiza kwambiri kubisa zenizeni za kusamutsidwa kwachinsinsi. Mwachitsanzo, ngati maulamuliro ofunikira adalanda uthenga wanu wobisika ndipo sangathe kuumasulira, koma akufunadi, ndiye kuti pali njira zomwe sizili pakompyuta zokopa ndikupeza zambiri. Zimamveka ngati dystopian, koma, mukuwona, izi ndizotheka kwenikweni. Choncho, zingakhale bwino kuonetsetsa kuti amene sayenera kudziwa n'komwe kuti kusamutsa kwachitika. Ofufuza a ku Poland anakonza njira yotereyi. Komanso, akufuna kuchita izi pogwiritsa ntchito protocol yomwe aliyense wogwiritsa ntchito intaneti amagwiritsa ntchito chikwi chimodzi patsiku.
Apa tikuyandikira ku Transmission Control Protocol (TCP). Kufotokozera mwatsatanetsatane zake zonse, ndithudi, sikumveka - ndizotalika, zotopetsa, ndipo omwe amazifuna amadziwa kale. Mwachidule, titha kunena kuti TCP ndi protocol wosanjikiza (ndiko kuti, imagwira ntchito "pa" IP ndi "pansi" ma protocol osanjikiza, monga HTTP, FTP kapena SMTP), yomwe imatsimikizira kutumizidwa kodalirika kwa data kuchokera kwa wotumiza kupita wolandira. Kutumiza kodalirika kumatanthauza kuti ngati paketi itayika kapena ikasinthidwa, TCP idzasamalira kutumiza paketiyo. Dziwani kuti kusintha kwa paketi pano sikukutanthauza kupotoza mwadala kwa deta, koma zolakwika zomwe zimachitika pathupi. Mwachitsanzo, pamene paketiyo inkayenda ndi mawaya amkuwa, tinthu tating'ono tating'ono tasintha mtengo wake kukhala wosiyana kapena tinatayika kwathunthu pakati pa phokoso (mwa njira, chifukwa cha Ethernet Bit Error Rate mtengo nthawi zambiri imatengedwa kukhala pafupifupi 10-8. ). Kutayika kwa paketi paulendo kumakhalanso kofala kwambiri pa intaneti. Zitha kuchitika, mwachitsanzo, chifukwa cha kuchuluka kwa ma routers, zomwe zimapangitsa kuti buffer kusefukira ndipo, chifukwa chake, kutaya mapaketi onse omwe angofika kumene. Nthawi zambiri, kuchuluka kwa mapaketi otaika ndi pafupifupi 0.1%, ndipo ndi mtengo wa magawo angapo, TCP imasiya kugwira ntchito bwino - chilichonse chidzakhala chochedwa kwambiri kwa wogwiritsa ntchito.
Choncho, tikuwona kuti kutumiza (kubwezeretsanso) mapaketi ndizochitika kawirikawiri za TCP ndipo, makamaka, ndizofunikira. Chifukwa chake osagwiritsa ntchito pazosowa za steganography, popeza TCP, monga tafotokozera pamwambapa, imagwiritsidwa ntchito paliponse (malinga ndi kuyerekezera kosiyanasiyana, lero gawo la TCP pa intaneti likufikira 80-95%). Chofunikira cha njira yomwe yaperekedwa ndikutumiza uthenga wotumizidwa osati zomwe zinali mu paketi yoyamba, koma zomwe tikuyesera kubisa. Komabe, kuzindikira kulowetsedwa koteroko sikophweka. Kupatula apo, muyenera kudziwa komwe mungayang'ane - kuchuluka kwa kulumikizana kwa TCP nthawi imodzi kudutsa woperekayo ndikokulirapo. Ngati mukudziwa pafupifupi mulingo wa retransmission mu netiweki, mukhoza kusintha steganographic kutumiza limagwirira kuti kugwirizana kwanu kusakhale osiyana ndi ena.
Inde, njira imeneyi si wopanda mavuto. Mwachitsanzo, kuchokera kumalingaliro othandiza, kukhazikitsa sikukhala kophweka - kudzafunika kusintha ma network mumayendedwe opangira, ngakhale palibe chovuta pa izi. Kuphatikiza apo, ngati muli ndi zothandizira zokwanira, ndizothekabe kuzindikira mapaketi "obisika" poyang'ana ndikusanthula paketi iliyonse pamaneti. Koma monga lamulo, izi sizingatheke, choncho nthawi zambiri amayang'ana mapaketi ndi malumikizidwe omwe amawonekera mwanjira ina, ndipo njira yomwe akufunira ndi yomwe imapangitsa kuti kulumikizana kwanu kusakhale kodabwitsa. Ndipo palibe amene akukuletsani kubisa zinsinsi zachinsinsi ngati zingachitike. Nthawi yomweyo, kulumikizana komweko kumatha kukhala kosasinthika kuti apangitse kukayikira pang'ono.
Olemba ntchito (mwa njira, kwa omwe ali ndi chidwi, she) adawonetsa pamlingo woyerekeza kuti njira yomwe yaperekedwa imagwira ntchito momwe amafunira. Mwina mtsogolomo wina adzagwiritsa ntchito lingaliro lawo pochita. Ndiyeno, mwachiyembekezo, padzakhala censorship pang'ono pa Intaneti.
Source: www.habr.com