A yau, kawai malalaci ba su rubuta game da fasahar blockchain ba, cryptocurrencies da yadda yake da kyau. Amma wannan labarin ba zai yabi wannan fasaha ba, za mu yi magana game da kasawarta da hanyoyin kawar da su.

Yayin aiki akan ɗayan ayyukan a Altirix Systems, aikin ya taso na amintacce, tabbatarwa mai juriya na bayanai daga tushen waje zuwa blockchain. Ya zama dole don tabbatar da canje-canje a cikin rikodin tsarin na uku kuma, bisa ga waɗannan canje-canje, aiwatar da ɗaya ko wani reshe a cikin dabarun kwangilar kai tsaye. Aiki a kallon farko ba shi da mahimmanci, amma lokacin da yanayin kuɗi na ɗaya daga cikin bangarorin da ke shiga cikin tsarin ya dogara da sakamakon aiwatar da shi, ƙarin buƙatun sun bayyana. Da farko, wannan cikakkiyar amana ce ga irin wannan ingantacciyar hanyar tabbatarwa. Amma farko abubuwa da farko.

Matsalar ita ce blockchain kanta wani abu ne mai cin gashin kansa, rufaffen, don haka kwangilar wayo a cikin blockchain ba su san komai game da duniyar waje ba. A lokaci guda, sharuɗɗan kwangila masu wayo suna da alaƙa da bayanai game da ainihin abubuwa (jinkirin jirgin, farashin musayar, da sauransu). Don kwangiloli masu wayo suyi aiki yadda yakamata, bayanan da aka karɓa daga wajen blockchain dole ne su zama abin dogaro kuma a tabbatar dasu. Ana magance wannan matsalar ta amfani da lafuzza irin su Town Crier da DECO. Waɗannan maganganun suna ba da damar kwangila mai wayo akan hanyar sadarwar blockchain don aminta da bayanai daga sabar gidan yanar gizo da aka amince; zamu iya cewa waɗannan su ne masu samar da ingantaccen bayani.

Oracles

Yi tunanin cewa kwangila mai wayo yana canja wurin 0.001 btc zuwa walat ɗin bitcoin idan ƙungiyar ƙwallon ƙafa da kuka fi so ta lashe gasar cin kofin Rasha. A cikin taron na gaske nasara, da smart kwangila bukatar canja wurin bayanai game da abin da kulob din ya ci nasara, da kuma da dama matsaloli tasowa a nan: inda za a samu wannan bayanin, yadda za a amince canja wurin shi zuwa smart kwangila da kuma yadda za a tabbatar da cewa bayanin. samu a cikin smart kwangila yana da inganci a zahiri ya zo daidai da gaskiya?

Idan ya zo ga tushen bayanai, za a iya samun yanayi guda 2: haɗa kwangila mai wayo zuwa gidan yanar gizo mai aminci inda aka adana bayanai game da sakamakon wasa a tsakiya, kuma zaɓi na biyu shine haɗa shafuka da yawa lokaci ɗaya sannan zaɓi bayanai daga mafi yawan tushe. wanda ke ba da bayanai iri ɗaya. Don tabbatar da daidaiton bayanan, ana amfani da lafuzza, misali Oraclize, wanda ke amfani da TLSNotary (TLS Notary Modification don Tabbatar da Sahihancin Bayanai). Amma akwai isassun bayanai akan Google game da Oraclize, kuma akwai kasidu da yawa akan Habré.A yau zan yi magana game da lafuzza masu amfani da wata hanya ta daban don isar da bayanai: Town Crier da DECO. Labarin yana ba da bayanin ka'idodin aiki na duka baka, da kuma cikakken kwatance.

Garin Crier

Town Crier (TC) IC3 (The Initiative for CryptoCurrencies and Contracts) ya gabatar da shi a cikin 2016 a CCS'16. Babban ra'ayin TC: canja wurin bayanai daga gidan yanar gizon zuwa kwangila mai wayo kuma tabbatar da cewa bayanan da TC ke bayarwa daidai yake da akan gidan yanar gizon. TC tana amfani da TEE (Trusted Execution Environment) don tantance ikon mallakar bayanai. Sigar asali ta TC ta bayyana yadda ake aiki tare da Intel SGX.
Town Crier ya ƙunshi wani sashi a cikin blockchain da wani sashi a cikin OS kanta - TC Server.

Kwangilar TC tana kan blockchain kuma tana aiki azaman ƙarshen gaba ga TC. Yana karɓar buƙatun daga CU (kwangilar mai wayo) kuma yana mayar da martani daga Sabar TC. A cikin uwar garken TC akwai Relay, wanda ke kafa alaƙa tsakanin enclave da Intanet (bidirectional traffic) kuma yana haɗa ɓarna tare da blockchain. Enclave ya ƙunshi progencl, wanda shine lambar da ke yin buƙatun daga blockchain kuma yana mayar da saƙonni zuwa blockchain tare da sa hannu na dijital, progencl yana ƙunshe da wani ɓangare na lambar kwangila mai wayo kuma da gaske yana aiwatar da wasu ayyukansa.

Za'a iya tunanin enclave na Intel SGX azaman ɗakin karatu da aka raba tare da API da ke gudana ta hanyar ecall. Ecall yana canja wurin sarrafawa zuwa ƙugiya. Enclave yana aiwatar da lambar sa har sai ya fita ko har sai an sami wani keɓancewa. Ana amfani da ocall don kiran ayyuka da aka ayyana a waje da kewaye. Ana aiwatar da ocall a waje da keɓaɓɓen kuma ana ɗaukarsa azaman kira mara aminci. Bayan an aiwatar da ocall, ana mayar da sarrafawa zuwa cikin ƙulli.

A cikin ɓangaren Enclave, an saita tashoshi mai tsaro tare da sabar gidan yanar gizo, enclave da kanta yana yin musafaha TLS tare da sabar da aka yi niyya kuma yana aiwatar da duk ayyukan sirri na ciki. An fitar da ɗakin karatu na TLS (mbedTLS) da rage lambar HTTP zuwa yanayin SGX. Hakanan, Enclave yana ƙunshe da takaddun takaddun CA tushen (tarin takaddun shaida) don tabbatar da takaddun shaida na sabar nesa. Request Handler yana karɓar buƙatun datagram a tsarin da Ethereum ya bayar, yana ɓarna shi kuma ya rarraba shi. Sannan yana haifar da ma'amalar Ethereum mai ɗauke da datagram ɗin da ake buƙata, sanya hannu tare da skTC kuma yana tura shi zuwa Relay.

Bangaren Relay ya haɗa da Interface Client, TCP, Blockchain Interface. Ana buƙatar Interface Abokin ciniki don tabbatar da lambar ɓoye da sadarwa tare da abokin ciniki. Abokin ciniki yana aika buƙatun shaida ta amfani da ecall kuma ya karɓi tambarin lokaci da skTC ya rattaba hannu tare da att (sa hannun shaida), sannan an tabbatar da att ta amfani da Sabis na Tabbatar da Intel (IAS), kuma amintaccen sabis na lokaci ya tabbatar da tambarin. Blockchain Interface yana tabbatar da buƙatun masu shigowa kuma yana sanya ma'amaloli akan blockchain don isar da bayanai. Geth babban abokin ciniki ne na Ethereum kuma yana ba da damar Relay don yin hulɗa tare da blockchain ta hanyar kiran RPC.

Yin aiki tare da TEE, TC yana ba ku damar gudanar da enclaves da yawa a layi daya, ta haka yana haɓaka saurin sarrafa bayanai da sau 3. Idan tare da enclave guda ɗaya gudun shine 15 tx/sec, to tare da 20 parallel run enclaves gudun yana ƙaruwa zuwa 65 tx/sec; don kwatanta, matsakaicin saurin aiki a cikin blockchain na Bitcoin shine 26 tx/sec.

Deco

An gabatar da DECO (Babban Oracles don TLS) a CCS'20, yana aiki tare da rukunin yanar gizon da ke tallafawa haɗin TLS. Yana tabbatar da sirrin bayanai da mutunci.
DECO tare da TLS yana amfani da ɓoyayyen ɓoyewa, don haka abokin ciniki da sabar gidan yanar gizo suna da maɓallan ɓoyewa, kuma abokin ciniki na iya ƙirƙira bayanan zaman TLS idan yana so. Don magance wannan matsalar, DECO tana amfani da ka'idar musafaha ta hanyoyi uku tsakanin mai tabbatarwa (kwangilar wayo), tabbatarwa (oracle) da sabar gidan yanar gizo (tushen bayanai).

Yadda DECO ke aiki shine mai tantancewa ya karɓi guntun bayanai D kuma ya tabbatar wa mai tabbatarwa cewa D ya fito daga uwar garken TLS S. Wata matsala kuma ita ce TLS baya sanya hannu kan bayanan kuma yana da wahala abokin ciniki na TLS ya tabbatar da cewa An karɓi bayanai daga daidai uwar garken daidai (wahalar provenance).

Ka'idar DECO tana amfani da maɓallan ɓoyayyen KEnc da KMac. Abokin ciniki yana aika buƙatar Q zuwa sabar gidan yanar gizon, amsa daga uwar garken R yana zuwa a cikin rufaffen tsari, amma abokin ciniki da uwar garken suna da KMac iri ɗaya, kuma abokin ciniki na iya ƙirƙira saƙon TLS. Maganin DECO shine "boye" KMac daga abokin ciniki (prover) har sai ya amsa bukatar. Yanzu an raba KMac tsakanin prover da verifier - KpMac da KvMac. Sabar tana karɓar KMac don ɓoye amsa ta amfani da aikin-ɓangaren maɓalli KpMac ⊕ KvMac = KMac.

Ta hanyar kafa musafaha ta hanyoyi uku, musayar bayanai tsakanin abokin ciniki da uwar garken za a yi tare da garantin tsaro.

Lokacin da ake magana game da tsarin baƙar fata, wanda ba zai iya kasa ambaton Chainlink ba, wanda ke da nufin ƙirƙirar hanyar sadarwa ta hanyar sadarwa na nodes masu dacewa da Ethereum, Bitcoin da Hyperledger, tare da la'akari da yanayin: kowane ɓangare na tsarin za a iya sabuntawa. A lokaci guda, don tabbatar da tsaro, Chainlink yana ba da kowane magana da ke shiga cikin aikin don ba da haɗin maɓalli (na jama'a da na sirri). Ana amfani da maɓalli na sirri don samar da sa hannun sa hannu wanda ya ƙunshi shawararsu ga buƙatar bayanai. Don samun amsa, ya zama dole a haɗa duk sa hannun sa hannu na baka na cibiyar sadarwa.

Chainlink yana shirin gudanar da PoC DECO na farko tare da mai da hankali kan aikace-aikacen kuɗi da aka raba su kamar Mixicles. A lokacin rubutawa, labarai sun fito kan Forbes cewa Chainlink ya sami DECO daga Jami'ar Cornell.

Hare-hare a kan baka

Daga mahangar tsaro na bayanai, an yi la'akari da hare-hare masu zuwa kan Town Crier:

1. Rogue smart-contact code allura akan nodes na TEE.
   Ma'anar harin: aika da lambar kwangila mai wayo da gangan ga TEE, don haka, maharin da ya sami damar shiga kumburi zai iya aiwatar da nasa kwangila mai wayo (zamba) akan bayanan da aka ɓoye. Koyaya, ƙimar dawowar za a rufaffen ɓoye tare da maɓalli na sirri, kuma hanya ɗaya tilo don samun damar irin waɗannan bayanan ita ce ta zubar da rubutun a kan dawowa/fitarwa.
   Kariya daga wannan harin ya ƙunshi ƙugiya da ke bincika daidaiton lambar da ke a adireshin yanzu. Ana iya samun wannan ta amfani da tsarin tuntuɓar inda aka ƙayyade adireshin kwangilar ta hashing code ɗin kwangila.

2. Rubutun sifa na kwangila yana canza ɗigogi.
   Ma'anar harin: Masu mallakar nodes waɗanda ake aiwatar da kwangiloli masu wayo suna da damar yin amfani da yanayin kwangilar a cikin ɓoyayyiyar tsari a wajen ɓoye. Mai kai hari, bayan ya sami iko da kumburi, zai iya kwatanta yanayin tuntuɓar kafin da bayan ciniki kuma zai iya tantance waɗanne muhawarar da aka shigar da kuma wace hanya ce ta kwangila mai wayo da aka yi amfani da ita, tunda lambar kwangilar mai kaifin baki da kanta da ƙayyadaddun fasahanta suna samuwa a bainar jama'a.
   Kariya wajen tabbatar da amincin kumburin kanta.

3. Hare-hare na gefen tashar.
   Wani nau'in hari na musamman wanda ke amfani da saka idanu akan ƙwaƙwalwar ajiya da samun damar cache a cikin yanayi daban-daban. Misalin irin wannan harin shine Prime and Probe.
   
   Umarnin kai hari:

   • t0: Maharin ya cika dukkan cache na bayanan wanda aka azabtar.
   • t1: Wanda aka azabtar yana aiwatar da lambar tare da damar ƙwaƙwalwar ajiya waɗanda suka dogara da mahimman bayanan wanda aka azabtar (maɓallan ɓoye). An zaɓi layin cache bisa ƙimar maɓalli. A cikin misalin da ke cikin wannan adadi, ana karanta keybit = 0 kuma ana karanta adreshin X a cikin cache line 2. Ana loda bayanan da aka adana a cikin X a cikin ma'ajin, tare da canza bayanan da ke can baya.
   • t2: Maharin ya duba ko wane layukan cache nasa aka kori-layukan da wanda abin ya shafa ya yi amfani da su. Ana yin hakan ta hanyar auna lokacin shiga. Ta maimaita wannan aiki ga kowane maɓalli na maɓalli, maharin yana samun maɓalli gaba ɗaya.

Kariyar kai hari: Intel SGX yana da kariya daga hare-haren tashoshi na gefe wanda ke hana sa ido kan abubuwan da suka shafi cache, amma harin Firayim da Binciken zai ci gaba da aiki saboda maharin yana sa ido kan abubuwan da ke faruwa a cikin tsarinsa kuma yana raba cache tare da wanda aka azabtar.

Don haka, a halin yanzu babu wani ingantaccen kariya daga wannan hari.

Hare-hare irin su Specter da Foreshadow (L1TF), kama da Prime da Probe, ana kuma san su. Suna ba ku damar karanta bayanai daga ƙwaƙwalwar ajiyar cache ta tashar ɓangare na uku. An ba da kariya daga raunin Specter-v2, wanda ke aiki da biyu daga cikin waɗannan hare-hare.

Dangane da DECO, musafaha ta hanyoyi uku yana ba da tabbacin tsaro:

1. Prover Integrity: Mai hackers ba zai iya gurbata bayanan asalin uwar garken ba kuma ba zai iya sa uwar garken ta karɓi buƙatun mara inganci ko amsa ba daidai ba ga buƙatun masu inganci. Ana yin wannan ta hanyar tsarin nema tsakanin uwar garken da prover.
2. Tabbatar da Mutunci: Mai tabbatar da kutse ba zai iya sa mai tabbatar ya karɓi amsoshi da ba daidai ba.
3. Sirri: Mai tabbatar da hacking yana bincika bayanan jama'a kawai (buƙata, sunan uwar garke).

A cikin DECO, raunin alluran zirga-zirga ne kawai zai yiwu. Na farko, tare da musafaha ta hanyoyi uku, mai tabbatarwa zai iya tabbatar da asalin sabar ta amfani da sabo. Koyaya, bayan musafaha, mai tabbatarwa dole ne ya dogara da alamomin Layer na cibiyar sadarwa (adiresoshin IP). Don haka, dole ne a kiyaye sadarwa tsakanin mai tabbatarwa da uwar garken daga allurar zirga-zirga. Ana samun wannan ta amfani da Proxy.

Kwatanta baka

Town Crier ya dogara ne akan yin aiki tare da ɓoye a ɓangaren uwar garken, yayin da DECO ke ba ku damar tabbatar da sahihancin asalin bayanai ta amfani da musafaha ta hanyoyi uku da ɓoye bayanan tare da maɓallan sirri. An gudanar da kwatancen waɗannan maganganu bisa ga ma'auni masu zuwa: aiki, tsaro, farashi da kuma amfani.

Garin Crier
Deco

yi
Mai sauri (0.6s don gamawa)
Sannu a hankali (10.50s don gama yarjejeniya)

aminci
Kadan amintacce
Mafi aminci

cost
Mafi tsada
Mai rahusa

aiki
Yana buƙatar kayan aiki na musamman
Yana aiki tare da kowane uwar garken da ke goyan bayan TLS

Ayyukan aiki: Don yin aiki tare da DECO, ana buƙatar musafaha ta hanyoyi uku, lokacin da aka saita ta LAN yana ɗaukar 0.37 seconds, don hulɗar bayan an kafa haɗin, 2PC-HMAC yana da tasiri (0,13 s a kowane rubutu). Ayyukan DECO ya dogara da samuwan TLS cipher suites, girman bayanan masu zaman kansu, da sarƙaƙƙiyar shaidar takamaiman aikace-aikace. Yin amfani da aikace-aikacen zaɓi na binary daga IC3 a matsayin misali: kammala yarjejeniya ta hanyar LAN yana ɗaukar kusan daƙiƙa 10,50. Idan aka kwatanta, Town Crier yana ɗaukar kusan daƙiƙa 0,6 don kammala irin wannan aikace-aikacen, wanda yayi saurin kusan sau 20 fiye da DECO. Duk abubuwa daidai suke, TC zai yi sauri.

Tsaro: Hare-hare a kan Intel SGX enclave (hare-haren tashoshi na gefe) yana aiki kuma yana iya haifar da lalacewar gaske ga mahalarta kwangilar wayo. Game da DECO, hare-haren da suka shafi allurar zirga-zirga yana yiwuwa, amma yin amfani da wakili yana rage irin waɗannan hare-haren zuwa kome ba. Don haka DECO ya fi aminci.

kudin: Farashin kayan aikin da ke goyan bayan Intel SGX ya fi farashin kafa yarjejeniya a DECO. Shi ya sa TC ya fi tsada.

Kayan aiki: Don yin aiki tare da Town Crier, ana buƙatar kayan aiki na musamman waɗanda ke tallafawa TEE. Misali, Intel SGX yana samun tallafi akan dangin Intel Core na ƙarni na 6 kuma daga baya. DECO yana ba ku damar yin aiki tare da kowane kayan aiki, kodayake akwai saitin DECO ta amfani da TEE. Dangane da tsarin saitin, musafaha ta hanyoyi uku na DECO na iya ɗaukar ɗan lokaci, amma wannan ba komai bane idan aka kwatanta da iyakancewar kayan aikin TC, don haka DECO ya fi aiki.

ƙarshe

Idan aka kalli maganganun guda biyu daban tare da kwatanta su akan sharuɗɗa huɗu, a bayyane yake cewa Town Crier yana ƙasa da DECO akan maki uku cikin huɗu. DECO ya fi dogara daga ra'ayi na tsaro na bayanai, mai rahusa kuma mafi amfani, ko da yake kafa yarjejeniya ta ƙungiyoyi uku na iya ɗaukar lokaci kuma yana da rashin amfaninsa, misali, ƙarin ayyuka tare da maɓallan ɓoyewa. TC yayi sauri fiye da DECO, amma raunin kai hari ta tashar tashoshi yana sa ya zama mai saurin rasa sirri. Dole ne a la'akari da cewa an gabatar da DECO a cikin Janairu 2020, kuma bai isa ba lokacin la'akari da shi lafiya. An kai hari garin Crier na tsawon shekaru 4 kuma ya yi gwaji da yawa, don haka amfani da shi a ayyuka da yawa ya dace.

source: www.habr.com