Ib qho lus qhia luv luv
Steganography, yog tias leej twg tsis nco qab, tab tom zais cov ntaub ntawv hauv qee lub thawv. Piv txwv li, hauv cov duab (sib tham ΠΈ ). Koj tuaj yeem nkaum cov ntaub ntawv hauv cov rooj pabcuam ntawm cov ntaub ntawv kaw lus (qhov no tau sau txog ), thiab txawm . Hmoov tsis zoo, tag nrho cov txheej txheem no muaj ib qho tsis zoo: txhawm rau kom tsis txhob "ntxig" cov ntaub ntawv rau hauv lub thawv, koj xav tau cov txheej txheem kev txawj ntse uas coj mus rau hauv tus account peculiarities ntawm lub thawv ntim khoom sab hauv. Thiab cov teeb meem tshwm sim nrog lub thawv tsis kam rau kev tswj hwm: piv txwv li, yog tias koj hloov daim duab me ntsis, cov ntaub ntawv zais ploj.
Puas yog nws muaj peev xwm ua tau yam tsis muaj cunning algorithms thiab hloov maj mam manipulations nrog cov ntaub ntawv, thiab tseem xyuas kom meej lub functionality ntawm lub thawv thiab ib theem txaus ntawm kev ruaj ntseg ntawm cov ntaub ntawv zais? Saib tom ntej, Kuv yuav hais - yog, koj tuaj yeem! Kuv tseem yuav muab ib qho khoom siv.
Ntshav cov ntsiab lus ntawm txoj kev
Lub tswv yim tseem ceeb yog qhov yooj yim li lub tshuab rau hauv pliaj: muaj qhov chaw ntawm lub disk uas lub operating system tsis tau sau rau (lossis sau qee zaus). Txhawm rau zam qhov yuav tsum tau tshawb nrhiav cov cheeb tsam no siv cov txheej txheem cunning, peb yuav siv redundancy - uas yog, peb yuav duplicate peb cov ntaub ntawv zais ntau, ntau zaus thoob plaws txhua qhov chaw ntawm lub disk. Tom qab ntawd, nyob rau sab saum toj ntawm tag nrho cov kev zoo nkauj no, koj tuaj yeem tsim cov partitions tsim nyog, hom ntaub ntawv kaw lus, sau cov ntaub ntawv thiab nruab OSes - txhua yam zoo ib yam, ib feem ntawm cov ntaub ntawv zais cia yuav raug cawm thiab rov qab tau, thiab rov ua dua yuav pab peb. muab tus thawj tag nrho ua ke los ntawm daim.
Qhov kom zoo dua ntawm txoj kev no yog pom tseeb: peb tsis nyob ntawm cov ntaub ntawv hom, lossis txawm nyob ntawm hom ntaub ntawv siv.
Qhov tsis zoo kuj yog, kuv xav tias, pom tseeb:
- Cov ntaub ntawv zais cia tsuas yog hloov tau los ntawm kev sau tag nrho cov disk, ua raws li kev tsim cov ntsiab lus pom rau tus neeg siv. Txawm li cas los xij, koj tsis tuaj yeem siv software uas rov tsim dua lub disk los ntawm cov duab: nws tseem yuav rov tsim cov ntaub ntawv zais cia yav dhau los.
- Qhov loj dua qhov ntim ntawm cov ntaub ntawv zais cia, qhov ntau dua qhov yuav poob qee cov ntaub ntawv.
- Retrieving cov ntaub ntawv los ntawm disk yuav siv sij hawm ntev. Los ntawm ob peb feeb mus rau ob peb hnub (hnub no disks loj).
Tam sim no cia peb mus rau qhov tshwj xeeb.
Nws yog qhov tseeb tias yog tias koj tsuas smear cov ntaub ntawv zais cia thoob plaws lub disk, nws tsuas yog muab zais ntawm qhov muag liab qab xwb. Yog hais tias koj muab koj ntsia nrog, hais, ib tug disk editor, cov ntaub ntawv yuav tshwm nyob rau hauv tag nrho nws lub yeeb koob. Yog li ntawd, nws yuav yog ib lub tswv yim zoo rau encrypt cov ntaub ntawv kom nws tsis tshwm sim. Peb yuav encrypt yooj yim, tab sis tastefully: siv aes256-cbc algorithm. Peb mam li nug tus neeg siv rau tus yuam sij encryption thiab cia nws tuaj nrog tus password zoo.
Cov lus nug tom ntej yog yuav ua li cas peb thiaj paub qhov txawv "zoo" cov ntaub ntawv los ntawm cov ntaub ntawv tsis zoo. Nov yog daim tshev yuav pab peb, tab sis tsis yog ib qho yooj yim, tab sis SHA1. Thiab yog dab tsi? Nws yog qhov zoo txaus rau git, yog li nws yuav haum rau peb thiab. Kev txiav txim siab: peb muab txhua daim ntawv khaws cia nrog ib daim tshev, thiab yog tias tom qab decryption nws phim, nws txhais tau hais tias kev decryption tau ua tiav.
Koj tseem yuav xav tau tus lej fragment thiab tag nrho ntev ntawm cov ntaub ntawv zais cia. Tus naj npawb fragment yog kom taug qab cov khoom twg peb twb tau txiav txim siab thiab qhov twg yog lawm. Qhov ntev tag nrho yuav muaj txiaj ntsig zoo rau peb thaum ua cov ntu kawg, kom tsis txhob sau cov ntaub ntawv tsis tsim nyog (uas yog, padding). Zoo, txij li thaum peb tseem muaj lub taub hau, peb yuav ntxiv lub npe ntawm cov ntaub ntawv zais cia rau ntawd. Nws yuav pab tau tom qab decryption, yog li tsis txhob twv yuav ua li cas qhib nws.
Kev sim cov txheej txheem hauv kev xyaum
Txhawm rau txheeb xyuas, cia peb siv qhov nruab nrab tshaj plaws - flash drive. Kuv pom ib qho qub nrog 1 GB muaj peev xwm, uas yog qhov tsim nyog rau kev sim. Yog tias koj, zoo li kuv, tuaj nrog lub tswv yim ntawm kev tsis thab nrog lub cev tawm, tab sis sim nws ntawm cov ntaub ntawv - daim duab disk, ces kuv mam li hais tam sim ntawd: nws yuav tsis ua haujlwm. Thaum formatting xws li "disk," Linux tsim cov ntaub ntawv dua, thiab tag nrho cov haujlwm tsis siv yuav tau sau nrog xoom.
Raws li lub tshuab nrog Linux, hmoov tsis zoo, kuv yuav tsum siv lub chaw nres tsheb huab cua ntawm Raspberry Pi 3 pw ntawm lub sam thiaj. Tsis muaj ntau lub cim xeeb nyob ntawd, yog li peb yuav tsis zais cov ntaub ntawv loj. Peb txwv peb tus kheej mus rau qhov loj tshaj plaws ntawm 10 megabytes. Kuj tsis muaj qhov taw qhia hauv kev zais cov ntaub ntawv uas me dhau: cov khoom siv sau cov ntaub ntawv rau disk hauv 4 KB pawg. Yog li ntawd, hauv qab no peb yuav txwv peb tus kheej mus rau 3 kb cov ntaub ntawv - nws haum rau ib pawg xws li.
Peb yuav thuam lub flash drive hauv theem, xyuas tom qab txhua theem seb cov ntaub ntawv zais puas tuaj yeem nyeem tau:
- Fast formatting hauv FAT16 hom nrog pawg loj ntawm 16 KB. Qhov no yog qhov Windows 7 muab los ua nrog lub flash drive uas tsis muaj cov ntaub ntawv kaw lus.
- Sau lub flash drive nrog txhua yam khib nyiab los ntawm 50%.
- Sau lub flash drive nrog txhua yam khib nyiab los ntawm 100%.
- "Long" formatting hauv FAT16 hom (overwriting txhua yam).
Thawj ob qhov kev sim, raws li qhov xav tau, tau ua tiav hauv kev yeej: cov khoom siv hluav taws xob tuaj yeem ua tiav 10 megabytes ntawm cov ntaub ntawv zais cia los ntawm flash drive. Tab sis tom qab lub flash drive tau ua kom muaj peev xwm nrog cov ntaub ntawv, qhov ua tsis tiav tau tshwm sim:
Total clusters read: 250752, decrypted: 158
ERROR: cannot write incomplete secretFile
Raws li koj tuaj yeem pom, tsuas yog 158 pawg tau ua tiav tiav (632 kilobytes ntawm cov ntaub ntawv nyoos, uas muab 636424 bytes ntawm payload). Nws yog qhov tseeb tias tsis muaj txoj hauv kev kom tau 10 megabytes ntawm no, thiab tseem ntawm cov pawg no muaj cov duplicates kom meej. Koj tsis tuaj yeem rov qab tau 1 megabyte li no. Tab sis peb tuaj yeem lav tias peb yuav rov qab tau 3 kilobytes ntawm cov ntaub ntawv zais cia los ntawm lub flash drive txawm tias tom qab nws tau formatted thiab sau rau lub peev xwm. Txawm li cas los xij, kev sim qhia tau tias nws muaj peev xwm rho tawm cov ntaub ntawv 120 kilobytes ntev los ntawm lub flash drive.
Qhov kev sim zaum kawg, hmoov tsis, pom tias tag nrho flash drive tau sau dua:
$ sudo ./steganodisk -p password /dev/sda
Device size: 250752 clusters
250700 99%
Total clusters read: 250752, decrypted: 0
ERROR: cannot write incomplete secretFile
Tsis muaj ib pawg tau dim lawm... Tu siab kawg li os! Ua ntej formatting, cia sim ua ib qho kev faib ntawm lub flash drive, thiab twb nyob rau hauv nws cov ntaub ntawv system. Los ntawm txoj kev, nws tuaj ntawm lub Hoobkas nrog raws nraim qhov formatting, yog li peb tsis ua dab tsi txawv.
Nws yog qhov xav tias qhov chaw muaj nyob hauv flash drive tau qis me ntsis.
Nws kuj tseem xav tias 10 megabytes tsis tuaj yeem muab zais rau ntawm tag nrho disk. Tab sis tam sim no tus naj npawb ntawm kev ua tiav decrypted pawg tau ntau dua ob npaug!
Total clusters read: 250752, decrypted: 405
Hmoov tsis zoo, nws tsis tuaj yeem sib sau ua ke ib megabyte los ntawm daim, tab sis ob puas kilobytes yooj yim.
Zoo, cov xov xwm hais txog lub xeem, 4th kos, lub sij hawm no yog kev xyiv fab: tag nrho formatting xws li ib tug flash drive tsis ua rau kev puas tsuaj ntawm tag nrho cov ntaub ntawv! 120 kilobytes ntawm cov ntaub ntawv zais cia haum txig rau hauv qhov chaw tsis siv.
Daim ntawv xeem xeem:
Me ntsis theorizing: txog qhov chaw dawb thiab tsis siv cov sectors
Yog tias koj tau faib koj lub hard drive rau hauv partitions, koj yuav pom tias nws tsis yog ib txwm muaj peev xwm faib tag nrho cov chaw dawb ntawm disk. Thawj ntu ib txwm pib nrog qee qhov indentation (feem ntau yog 1 megabyte, lossis 2048 sectors). Hauv qab ntu kawg, nws kuj tshwm sim tias tseem muaj "tail" me me ntawm cov khoom tsis siv. Thiab qee zaum muaj qhov sib txawv ntawm ntu, txawm tias tsis tshua muaj.
Hauv lwm lo lus, muaj cov haujlwm ntawm lub disk uas tsis tuaj yeem nkag mus tau thaum lub sijhawm ua haujlwm nrog lub disk, tab sis cov ntaub ntawv tuaj yeem sau rau cov haujlwm no! Thiab qhov ntawd txhais tau tias nyeem thiab. Kho rau lub fact tias kuj muaj ib tug muab faib lub rooj thiab bootloader code, uas yog nyob rau hauv qhov chaw khoob ntawm qhov pib ntawm lub disk.
Cia peb so ntawm cov ntu ib ntus thiab saib daim disk los ntawm tus noog qhov muag pom, yog li hais lus. Ntawm no peb muaj ib qho kev faib seem ntawm lub disk. Cia peb tsim cov ntaub ntawv kaw lus hauv nws. Peb puas tuaj yeem hais tias qee qhov haujlwm ntawm lub disk tseem tsis tau tshem tawm?
E-e-e - drum roll! Cov lus teb yuav luag ib txwm muaj! Tseeb, nyob rau hauv feem ntau, tsim ib cov ntaub ntawv system los sau tsuas yog ob peb blocks ntawm kev pab cuam cov ntaub ntawv rau lub disk, thiab txwv tsis pub cov ntsiab lus ntawm muab faib tsis hloov.
Thiab tseem - purely empirically - peb tuaj yeem xav tias cov ntaub ntawv kaw lus tsis tuaj yeem nyob txhua qhov chaw tau faib rau nws mus txog qhov kawg ntu. Piv txwv li, FAT16 cov ntaub ntawv kaw lus nrog pawg loj ntawm 64 kilobytes pom tseeb tsis tuaj yeem ua tiav qhov kev faib nrog qhov loj tsis yog ntau yam ntawm 64 kilobytes. Thaum kawg ntawm ntu ntu no yuav tsum muaj "tus Tsov tus tw" ntawm ntau qhov chaw, nkag tsis tau rau cov neeg siv cov ntaub ntawv khaws cia. Txawm li cas los xij, qhov kev xav no tsis tuaj yeem lees paub qhov kev sim.
Yog li, txhawm rau ua kom qhov chaw muaj ntau tshaj plaws rau lub steganogram, koj yuav tsum siv cov ntaub ntawv nrog cov pawg loj dua. Koj tuaj yeem tsim ib qho kev faib tawm, txawm tias qhov no tsis tsim nyog (ntawm lub flash drive, piv txwv li). Tsis tas yuav tsim cov seem khoob lossis tawm hauv qhov chaw tsis muaj kev faib - qhov no yuav nyiam cov neeg nyiam.
Kev siv rau kev sim
Koj tuaj yeem kov qhov chaws ntawm qhov chaw siv hluav taws xob
Txhawm rau tsim, koj yuav xav tau Qt version 5.0 lossis siab dua thiab OpenSSL. Yog tias ib yam dab tsi tsis ua haujlwm, koj yuav tau hloov kho cov ntaub ntawv steganodisk.pro.
Koj tuaj yeem hloov cov pawg loj ntawm 4 KB rau, hais, 512 bytes (hauv secretfile.h). Nyob rau tib lub sijhawm, tus nqi ntawm cov ntaub ntawv kev pabcuam yuav nce ntxiv: header thiab checksum nyob ruaj 68 bytes.
Koj yuav tsum tau khiav cov nqi hluav taws xob, tau kawg, nrog cov neeg siv hauv paus txoj cai, thiab ceev faj. Yuav tsis muaj lus nug ua ntej overwriting cov ntaub ntawv teev tseg los yog ntaus ntawv!
Txaus siab rau.
Tau qhov twg los: www.hab.com