{"id":93794,"date":"2020-09-10T07:42:27","date_gmt":"2020-09-10T05:42:27","guid":{"rendered":"https:\/\/prohoster.info\/blog\/administrirovanie\/town-crier-vs-deco-kakoj-orakul-ispolzovat-v-blokchejne"},"modified":"2020-09-10T07:42:27","modified_gmt":"2020-09-10T05:42:27","slug":"town-crier-vs-deco-kakoj-orakul-ispolzovat-v-blokchejne","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/administrirovanie\/town-crier-vs-deco-kakoj-orakul-ispolzovat-v-blokchejne","title":{"rendered":"Town Crier vs DECO: cili orakull t\u00eb p\u00ebrdoret n\u00eb blockchain?","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Sot k\u00ebrkohet vet\u00ebm nga ata q\u00eb jan\u00eb me fat q\u00eb kan\u00eb shkruar p\u00ebr teknologjin\u00eb blockchain, criptovalutat dhe sa e shk\u00eblqyer \u00ebsht\u00eb ajo. Por n\u00eb k\u00ebt\u00eb artikull nuk do t\u00eb ket\u00eb l\u00ebvdata p\u00ebr k\u00ebt\u00eb teknologji, do t\u00eb flasim pik\u00ebrisht p\u00ebr disavantazhet e saj dhe m\u00ebnyrat p\u00ebr t\u2019i zgjidhur ato. <\/p>\n

<\/p>\n

\"Town<\/p>\n

<\/p>\n

Gjat\u00eb pun\u00ebs n\u00eb nj\u00eb nga projektet n\u00eb kompanin\u00eb Altirix Systems, u shfaq nevoja p\u00ebr nj\u00eb konfirmim t\u00eb sigurt dhe t\u00eb q\u00ebndruesh\u00ebm ndaj censur\u00ebs t\u00eb t\u00eb dh\u00ebnave nga nj\u00eb burim t\u00eb jasht\u00ebm p\u00ebr blockchain. Duhej t\u00eb konfirmoheshin ndryshimet n\u00eb regjistrimet e nj\u00eb sistemi t\u00eb tret\u00eb dhe n\u00eb p\u00ebrputhje me k\u00ebto ndryshime t\u00eb ekzekutohej nj\u00eb deg\u00eb n\u00eb logjik\u00ebn e kontrat\u00ebs inteligjente. Detyra n\u00eb pamje t\u00eb par\u00eb duket mjaft e thjesht\u00eb, por kur rezultati i saj ndikon n\u00eb gjendjen financiare t\u00eb nj\u00eb prej pal\u00ebve p\u00ebrfshira, shfaqen k\u00ebrkesa t\u00eb tjera. Para s\u00eb gjithash, kjo \u00ebsht\u00eb besimi i plot\u00eb n\u00eb nj\u00eb mekaniz\u00ebm t\u00eb till\u00eb validimi. Por gjith\u00e7ka me rend. <\/p>\n

<\/a><\/noindex><\/p>\n

Problemi p\u00ebrb\u00ebhet nga fakti se blockchain as vet\u00eb \u00ebsht\u00eb nj\u00eb objekt autonom dhe i mbyllur, prandaj kontratat inteligjente brenda blockchain nuk din\u00eb asgj\u00eb p\u00ebr bot\u00ebn e jashtme. N\u00eb t\u00eb nj\u00ebjt\u00ebn koh\u00eb, kushtet e kontratave inteligjente shpesh lidhen me informacione mbi realitetin (vonesa t\u00eb fluturimeve, kurset e k\u00ebmbimit etj.). P\u00ebr t\u00eb siguruar funksionimin e duhur t\u00eb kontratave inteligjente, informacioni i marr\u00eb jasht\u00eb blockchain duhet t\u00eb jet\u00eb i besuesh\u00ebm dhe i verifikuar. Ky problem zgjidhet p\u00ebrmes p\u00ebrdorimit t\u00eb orakulave, si Town Crier dhe DECO. K\u00ebta orakul\u00eb lejojn\u00eb kontratave inteligjente n\u00eb rrjetin blockchain t'i besojn\u00eb informacionit nga nj\u00eb server web t\u00eb verifikuar, mund t\u00eb thuhet se ata jan\u00eb furnizues t\u00eb informacionit t\u00eb besuesh\u00ebm. <\/p>\n

<\/p>\n

Orakul\u00ebt<\/h1>\n

<\/p>\n

Imagjinoni se nj\u00eb kontrat\u00eb inteligjente kryen nj\u00eb transferim prej 0.001 btc n\u00eb portofolin tuaj bitcoin n\u00eb rast se klubi juaj i preferuar fiton kup\u00ebn e Rusis\u00eb. N\u00eb rastin e nj\u00eb fitoreje t\u00eb v\u00ebrtet\u00eb, kontrat\u00ebs inteligjente duhet t\u2019i d\u00ebrgohet informacioni se cili klub fitoi, dhe k\u00ebtu lindin disa probleme: ku mund ta gjejm\u00eb k\u00ebt\u00eb informacion, si ta d\u00ebrgojm\u00eb at\u00eb n\u00eb m\u00ebnyr\u00eb t\u00eb sigurt n\u00eb kontrat\u00ebn inteligjente dhe si t\u00eb sigurohemi q\u00eb informacioni i ardhur n\u00eb kontrat\u00ebn inteligjente p\u00ebrputhet me realitetin? <\/p>\n

<\/p>\n

N\u00eb \u00e7\u00ebshtjen e burimit t\u00eb informacionit mund t\u00eb jen\u00eb 2 skenar\u00eb: lidhja e kontrat\u00ebs inteligjente me nj\u00eb faqe t\u00eb besueshme, ku informacioni mbi rezultatet e ndeshjeve ruhet n\u00eb m\u00ebnyr\u00eb qendrore dhe varianti i dyt\u00eb \u2014 t\u00eb lidhemi menj\u00ebher\u00eb me disa faqe dhe m\u00eb pas t\u00eb b\u00ebjm\u00eb nj\u00eb p\u00ebrzgjedhje t\u00eb informacionit nga shumica e burimeve q\u00eb ofrojn\u00eb t\u00eb dh\u00ebna t\u00eb nj\u00ebjta. P\u00ebr t\u00eb siguruar saktesin\u00eb e informacionit, p\u00ebrdoren orakul\u00eb, si Oraclize, q\u00eb p\u00ebrdor TLSNotary (Modifikimi i TLS p\u00ebr t\u00eb provuar autencitetin e t\u00eb dh\u00ebnave). Por p\u00ebr Oraclize informacioni n\u00eb Google \u00ebsht\u00eb mjaftuesh\u00ebm dhe n\u00eb Habr jan\u00eb disa artikuj, un\u00eb sot do t\u00eb flas p\u00ebr orakul\u00ebt q\u00eb p\u00ebrdorin nj\u00eb qasje pak ndryshe p\u00ebr d\u00ebrgimin e informacionit: Town Crier dhe DECO. N\u00eb artikull jan\u00eb p\u00ebrshkruar parimet e pun\u00ebs s\u00eb t\u00eb dy orakul\u00ebve, si dhe nj\u00eb krahasim i detajuar. <\/p>\n

<\/p>\n

Town Crier<\/h1>\n

<\/p>\n

Town Crier (TC) u prezantua nga IC3 (Iniciativa p\u00ebr Kriptovalutat dhe Kontratate) n\u00eb vitin 2016 n\u00eb CCS\u201916. Ideja kryesore e TC: t\u00eb d\u00ebrgoj\u00eb informacionin nga nj\u00eb faqe web n\u00eb kontrat\u00ebn inteligjente dhe t\u00eb siguroj\u00eb q\u00eb informacioni i d\u00ebrguar nga TC \u00ebsht\u00eb i nj\u00ebjt\u00eb me at\u00eb n\u00eb faqen e internetit. TC p\u00ebrdor TEE (Mjedisi i Ekzekutimit t\u00eb Besuar) p\u00ebr t\u00eb garantuar autenticitetin e t\u00eb dh\u00ebnave. N\u00eb versionin origjinal, TC p\u00ebrshkruan funksionimin me Intel SGX.
\nTown Crier p\u00ebrb\u00ebhet nga nj\u00eb pjes\u00eb brenda blockchain dhe nj\u00eb pjes\u00eb brenda vet\u00eb OS \u2013 TC Server.
\n\"Town
\nKontrata TC ndodhet n\u00eb blockchain dhe vepron si frontend p\u00ebr TC. Ajo pranon k\u00ebrkesa nga CU (kontrata inteligjente e p\u00ebrdoruesit) dhe kthen nj\u00eb p\u00ebrgjigje nga TC Server. Brenda TC Server ndodhet Relay, i cili krijon lidhjen e enklav\u00ebs me internetin (trafiku dy-direksional) dhe lidh enklav\u00ebn me blockchain. Enclave p\u00ebrmban progencl, i cili \u00ebsht\u00eb kodi q\u00eb ekzekuton k\u00ebrkesat nga blockchain dhe kthen mesazhe n\u00eb blockchain me nj\u00eb n\u00ebnshkrim digjital, progencl p\u00ebrmban nj\u00eb pjes\u00eb t\u00eb kodit t\u00eb kontrat\u00ebs inteligjente dhe n\u00eb thelb ekzekuton disa nga funksionet e saj. <\/p>\n

<\/p>\n

Enklava Intel SGX mund t\u00eb konsiderohet si nj\u00eb bibliotek\u00eb e zakonshme me API, e cila punon p\u00ebrmes ecall. Ecall transferon kontrollin n\u00eb enklav\u00eb. Enklava ekzekuton kodin e saj, derisa t\u00eb p\u00ebrfundoj\u00eb, ose derisa t\u00eb ndodhi nj\u00eb p\u00ebrjashtim. P\u00ebr thirrjen e funksioneve, t\u00eb p\u00ebrcaktuara jasht\u00eb enklav\u00ebs, p\u00ebrdoren ocall. Ocall ekzekutohet jasht\u00eb enklav\u00ebs dhe p\u00ebrpunohet prej saj si nj\u00eb thirrje e pasigurt. Pas ekzekutimit t\u00eb ocall, kontrolli kthehet n\u00eb enklav\u00eb.
\n\"Town
\nN\u00eb pjes\u00ebn Enclave, ndodhet konfigurimi i kanalit t\u00eb sigurt me serverin web; Enclave vet\u00eb kryen TLS handshake me serverin e synuar dhe realizon t\u00eb gjitha operacionet kriptografike brenda vetes. Biblioteka TLS (mbedTLS) dhe kodi HTTP jan\u00eb eksportuar n\u00eb m\u00ebnyr\u00eb t\u00eb reduktuar n\u00eb ambientin SGX. Gjithashtu, Enclave p\u00ebrmban certifikatat root CA (nj\u00eb koleksion certifikatash) p\u00ebr t\u00eb verifikuar certifikatat e server\u00ebve t\u00eb larg\u00ebt. Request Handler pranon nj\u00eb k\u00ebrkes\u00eb datagram n\u00eb formatin e ofruar nga Ethereum, e dekripton at\u00eb dhe e analizon. Pastaj gjeneron nj\u00eb transaksion Ethereum q\u00eb p\u00ebrmban datagramin e k\u00ebrkuar, e n\u00ebnshkruan at\u00eb me skTC dhe e d\u00ebrgon n\u00eb Relay.<\/p>\n

<\/p>\n

Pjesa Relay p\u00ebrfshin Client Interface, TCP, Blockchain Interface. Client Interface \u00ebsht\u00eb i nevojsh\u00ebm p\u00ebr atestimin e kodit t\u00eb Enclave dhe komunikimin me klientin. Klienti d\u00ebrgon nj\u00eb k\u00ebrkes\u00eb p\u00ebr atestim p\u00ebrmes ecall dhe merr nj\u00eb timestamp t\u00eb n\u00ebnshkruar me skTC s\u00eb bashku me att (n\u00ebnshkrimi i atestimit); m\u00eb pas, att konfirmohet p\u00ebrmes Sh\u00ebrbimit t\u00eb Atestimit Intel (IAS), nd\u00ebrsa timestamp verifikohet nga nj\u00eb sh\u00ebrbim t\u00eb besuesh\u00ebm t\u00eb koh\u00ebs. Blockchain Interface verifikon k\u00ebrkesat e pranuara dhe vendos transaksionet n\u00eb blockchain p\u00ebr t\u00eb d\u00ebrguar datagramet. Geth \u00ebsht\u00eb klienti zyrtar i Ethereum dhe lejon Relay t\u00eb interaktoj\u00eb me blockchain p\u00ebrmes RPC calls. <\/p>\n

<\/p>\n

Duke punuar me TEE, TC e lejon \u00e7eljen e disa Enclaves nj\u00ebkoh\u00ebsisht, duke rritur k\u00ebshtu shpejt\u00ebsin\u00eb e p\u00ebrpunimit t\u00eb informacionit me 3 her\u00eb. N\u00ebse me nj\u00eb Enclave aktive shpejt\u00ebsia ishte 15 tx\/sec, at\u00ebher\u00eb me 20 Enclaves t\u00eb hapura nj\u00ebkoh\u00ebsisht shpejt\u00ebsia rritet n\u00eb 65 tx\/sec; p\u00ebr krahasim, shpejt\u00ebsia maksimale e pun\u00ebs n\u00eb blockchain-in Bitcoin \u00ebsht\u00eb 26 tx\/sec.<\/p>\n

<\/p>\n

DECO<\/h1>\n

<\/p>\n

DECO (Orakujt e decentralizuar p\u00ebr TLS) u prezantua n\u00eb CCS'20, punon me faqet q\u00eb mb\u00ebshtesin lidhjen TLS. Siguron privat\u00ebsin\u00eb dhe integritetin e t\u00eb dh\u00ebnave.
\nDECO me TLS p\u00ebrdor enkriptimin simetrik, duke lejuar q\u00eb klienti dhe serveri web t\u00eb ken\u00eb \u00e7el\u00ebsa enkriptimi dhe, n\u00ebse klienti d\u00ebshiron, mund t\u00eb manipuloj\u00eb t\u00eb dh\u00ebnat e sesionit TLS. P\u00ebr zgjidhjen e k\u00ebtij problemi, DECO p\u00ebrdor nj\u00eb protokoll tre-an\u00ebtar\u00ebsh nd\u00ebrshtes\u00eb mes prover (kontrata inteligjente), verifier (orakulli) dhe web-server (burimi i t\u00eb dh\u00ebnave).<\/p>\n

<\/p>\n

\"Town<\/p>\n

<\/p>\n

Principi i operimit t\u00eb DECO q\u00ebndron n\u00eb faktin se provuesi (prover) merr nj\u00eb pjes\u00eb t\u00eb t\u00eb dh\u00ebnave D dhe konfirmon p\u00ebr verifikuesin (verifier) se D ka ardhur nga serveri TLS S. Problemi tjet\u00ebr \u00ebsht\u00eb se TLS nuk n\u00ebnshkruan t\u00eb dh\u00ebnat dhe \u00ebsht\u00eb e v\u00ebshtir\u00eb p\u00ebr klientin TLS t\u00eb provoj\u00eb se t\u00eb dh\u00ebnat jan\u00eb marr\u00eb pik\u00ebrisht nga ai server (v\u00ebshtir\u00ebsi n\u00eb provinenc\u00eb). <\/p>\n

<\/p>\n

N\u00eb protokollin DECO p\u00ebrdoren \u00e7el\u00ebsa enkriptimi KEnc dhe KMac. Klienti d\u00ebrgon nj\u00eb k\u00ebrkes\u00eb Q n\u00eb server web<\/a>, p\u00ebrgjigja nga serveri R vjen e enkriptuar, por klienti dhe serveri zot\u00ebrojn\u00eb t\u00eb nj\u00ebjtin KMac, dhe klienti mund t\u00eb sajoj\u00eb mesazhin TLS. Zgjidhja nga DECO \u00ebsht\u00eb t\u00eb \"fsheh\u00eb\" KMac nga klienti (prover) derisa ai t\u00eb p\u00ebrgjigjet n\u00eb k\u00ebrkes\u00eb. Tani KMac \u00ebsht\u00eb i ndar\u00eb midis prover dhe verifier \u2014 KpMac dhe KvMac. Serveri merr KMac p\u00ebr enkriptimin e p\u00ebrgjigjes p\u00ebrmes operacionit mbi pjes\u00ebt e \u00e7el\u00ebsit KpMac \u2295 KvMac = KMac.<\/p>\n

<\/p>\n

Duke konfiguruar nj\u00eb duar t\u00eb tret\u00eb p\u00ebr shk\u00ebmbimin e t\u00eb dh\u00ebnave nd\u00ebrmjet klientit dhe serverit, do t\u00eb kryhet me nj\u00eb garanci sigurie.
\n\"Town
\nDuke folur p\u00ebr sistemin e orakujve t\u00eb decentralizuar, nuk mund t\u00eb mos p\u00ebrmendim Chainlink, i cili synon t\u00eb krijoj\u00eb nj\u00eb rrjet t\u00eb decentralizuar t\u00eb nyjeve t\u00eb orakujve, t\u00eb p\u00ebrputhsh\u00ebm me Ethereum, Bitcoin dhe Hyperledger, duke u bazuar n\u00eb modularitet: \u00e7do pjes\u00eb e sistemit mund t\u00eb p\u00ebrdit\u00ebsohet. P\u00ebr m\u00eb tep\u00ebr, p\u00ebr t\u00eb siguruar sigurin\u00eb, Chainlink ofron \u00e7do orakulli q\u00eb merr pjes\u00eb n\u00eb nj\u00eb k\u00ebrkes\u00eb p\u00ebr t\u00eb dh\u00ebn\u00eb nj\u00eb kombinim \u00e7elesh (publik dhe privat). \u00c7el\u00ebsi privat p\u00ebrdoret p\u00ebr t\u00eb gjeneruar nj\u00eb n\u00ebnshkrim t\u00eb pjessh\u00ebm q\u00eb p\u00ebrmban zgjidhjen e tyre n\u00eb k\u00ebrkes\u00ebn e t\u00eb dh\u00ebnave. P\u00ebr t\u00eb marr\u00eb nj\u00eb p\u00ebrgjigje, k\u00ebrkohet bashkimi i t\u00eb gjitha n\u00ebnshkrimeve t\u00eb pjesshme t\u00eb orakujve t\u00eb rrjetit.<\/p>\n

<\/p>\n

Chainlink planifikon t\u00eb realizoj\u00eb nj\u00eb Proof of Concept (PoC) t\u00eb DECO me fokus tek aplikacionet financiare t\u00eb decentralizuara, si\u00e7 jan\u00eb Mixicles. N\u00eb koh\u00ebn e shkrimit t\u00eb k\u00ebtij artikulli, u publikua nj\u00eb lajm n\u00eb Forbes se Chainlink kishte bler\u00eb DECO nga Universiteti Cornell.<\/p>\n

<\/p>\n

Sulmet ndaj orakujve<\/h1>\n

<\/p>\n

\"Town<\/p>\n

<\/p>\n

N\u00eb k\u00ebndv\u00ebshtrimin e siguris\u00eb informative, u shqyrtuan sulmet e m\u00ebposhtme ndaj Town Crier:<\/p>\n

<\/p>\n

    \n
  1. \n

    Injeksioni i kodit t\u00eb kontrat\u00ebs inteligjente te nodet TEE.
    \nThelbi i sulmit: transmetimi n\u00eb TEE i nj\u00eb kodi t\u00eb dyshimt\u00eb t\u00eb kontrat\u00ebs inteligjente, k\u00ebshtu q\u00eb nj\u00eb sulmues, i cili ka akses n\u00eb nyj\u00eb, do t\u00eb ket\u00eb mund\u00ebsin\u00eb t\u00eb ekzekutoj\u00eb kontrat\u00ebn e tij (t\u00eb mashtrimit) mbi t\u00eb dh\u00ebnat e dekriptuara. Megjithat\u00eb, vlerat e kthyer do t\u00eb jen\u00eb t\u00eb enkriptuara me \u00e7el\u00ebsin privat, dhe alternativa e vetme p\u00ebr akses n\u00eb t\u00eb dh\u00ebna t\u00eb tilla \u00ebsht\u00eb rrjedhja e tekstit t\u00eb enkriptuar gjat\u00eb kthimit\/zhvendosjes.
    \nMbrojtja nga ky sulm q\u00ebndron n\u00eb verifikimin e Enclave-it p\u00ebr sakt\u00ebsin\u00eb e kodit q\u00eb ndodhet n\u00eb adres\u00ebn aktuale. Kjo mund t\u00eb arrihet p\u00ebrmes nj\u00eb skeme adresimi, ku adresa e kontrat\u00ebs p\u00ebrcaktohet nga hashimi i kodit t\u00eb kontrat\u00ebs. <\/p>\n

    \n<\/li>\n

  2. \n

    Ndryshimet e ciphertext t\u00eb gjendjes s\u00eb kontrat\u00ebs rrjedhin.
    \nThe essence of the attack: Node owners where smart contracts execute have access to the contract state in encrypted form outside the enclave. An attacker who gains control of a node can compare the contract state before and after a transaction, determining which arguments were provided and which specific method of the smart contract was used, as the smart contract code and its technical specifications are publicly available.
    \nProtection in ensuring the reliability of the node itself.<\/p>\n

    \n<\/li>\n

  3. \n

    Side-channel attacks.
    \nA special type of attacks that utilize monitoring access to memory and the cache of the enclave in various scenarios. An example of such an attack is Prime and Probe.
    \n\"Town
    \nThe procedure for carrying out an attack:<\/p>\n

    <\/p>\n