Kimanta Tsaron Yarjejeniyar Hujjar Aiki (PoW): Tsarin Ma'auni Da Yawa

1. Gabatarwa & Bayanin Matsala

Tun lokacin da aka ƙaddamar da Yarjejeniyar Nakamoto (NC) ta Bitcoin, ɗaruruwan kudade na sirri sun karɓi hanyoyin Hujjar Aiki (PoW) don kula da littattafan bayanai masu rarrabuwa. Duk da haka, bincike na asali ya fallasa manyan kurakuran tsaro a cikin NC, musamman rashin samun cikakkiyar ingancin sarkar. Wannan rashi yana ba wa ma'adinan mugunta damar canza littafin bayanai na jama'a, yana sauƙaƙe hare-hare kamar hako ma'adinai na son kai, kashe kuɗi sau biyu, da kuma 'feather-forking'. Don mayar da martani, yawancin yarjejeniyoyin "ingantattun" (misali, Ethereum, Bitcoin-NG, Fruitchains) sun bayyana, kowannensu yana da'awar ingantaccen tsaro. Duk da haka, ba tare da daidaitaccen tsarin kimantawa na ƙididdiga ba, waɗannan da'awar sun kasance na kansu kuma suna rarrabe tsakanin al'ummomin ilimi da masu haɓakawa. Wannan takarda ta magance wannan gibi mai mahimmanci ta hanyar gabatar da tsarin ma'auni da yawa don nazarin tsaron yarjejeniyar PoW a zahiri kuma ta yi amfani da shi don bayyana cewa, har zuwa yau, babu wata yarjejeniyar PoW da ta cimma ingantaccen tsaro.

600+

Kudaden sirri na tushen PoW (har zuwa Nuwamba 2018)

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Yarjejeniyoyin da suka cimma ingantaccen ingancin sarkar

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Manyan hanyoyin kai hari da aka bincika

2. Tsarin Kimanta Tsaro

Tsarin da aka gabatar yana motsawa fiye da da'awar inganci don kafa ma'auni na ƙididdiga, masu kwatankwacinsu don tsaron PoW. An gina shi bisa zaton cewa ingancin sarkar shine mabuɗin rashin canzawar littafin bayanai.

2.1 Ma'aunin Tsaro na Asali

Tsarin yana kimanta yarjejeniyoyi bisa ginshiƙai huɗu:

Ingancin Sarkar (CQ): Kashi na tubalan a cikin sarkar mafi tsawo da ma'adinan masu bin ƙa'ida (gaskiya) suka haƙa. A bisa ƙa'ida, ga wani yanki na sarkar mai tubalan $k$, $CQ = \frac{\text{\# tubalan gaskiya}}{k}$.
Daidaitawar Ƙarfafawa: Yana auna ko ma'adinan masu hankali suna haɓaka riba ta hanyar bin yarjejeniyar. Rushewa a nan yana nuna rauni ga hako ma'adinai na son kai.
Ribin Juyarwa: Yana ƙididdige ikon maharin sake rubuta tarihi don kashe kuɗi sau biyu, sau da yawa ana yin samfurinsa azaman aiki na ƙarfin hash ɗinsa $\alpha$ da zurfin tabbatarwa $z$.
Mai Sauƙin Takunkumi: Yana kimanta yuwuwar hare-haren 'feather-forking' waɗanda ke tilasta ma'adinan masu hankali su ware takamaiman ma'amaloli.

2.2 Muhimmancin Ingancin Sarkar

Ƙarancin ingancin sarkar kai tsaye yana lalata alkawarin blockchain na rashin canzawa. Idan ma'adinan mugunta za su iya maye gurbin tubalan gaskiya akai-akai, suna sarrafa labarin tarihin ma'amala. Tsarin ya nuna cewa cimma ingancin sarkar daidai gwargwado da ƙarfin hash na gaskiya (watau $CQ \geq 1-\alpha$) shine sharaɗi mai mahimmanci, amma ba wadatar ba, don ingantaccen tsaro.

2.3 Hanyoyin Kai Hari & Tsarin Lalacewa

Hako Ma'adinai na Son Kai: Mahara suna riƙe tubalan don ɓata aikin ma'adinan gaskiya, suna samun rabo maras daidaituwa na lada ($>\alpha$).
Kashe Kuɗi Sau Biyu: Mahari a ɓoye yana haƙa reshe don maye gurbin ma'amala bayan an isar da kaya, yana sanya ainihin biyan kuɗi mara inganci.
Feather-Forking: Hari na tilastawa inda mahari ke barazanar yin maraya ga tubalan da ke ɗauke da wasu ma'amaloli, yana tilasta ma'adinan takunkumi su.

3. Binciken Yarjejeniya & Binciken

Yin amfani da tsarin ta hanyar binciken tsarin yanke shawara na Markov yana haifar da ƙaƙƙarfan ƙarshe.

3.1 Raunin Yarjejeniyar Nakamoto (NC)

An tabbatar cewa ingancin sarkar na NC bai cika ba. Mahari mai ƙarfin hash $\alpha$ zai iya cimma kashi na tubalan a cikin babban sarkar fiye da $\alpha$. Wannan shine tushen rauninsa ga duk hare-hare uku da aka bincika.

3.2 Binciken Yarjejeniyoyin da ba NC ba

Takardar tana kimanta yarjejeniyoyi kamar Ethereum (GHOST), Bitcoin-NG, DECOR+, Fruitchains, da Subchains. Babban binciken: Babu wanda ya cimma ingantaccen ingancin sarkar ko cikakkiyar juriya ga duk hare-hare uku. Wasu suna inganta ma'auni ɗaya a kan ɗayan (misali, haɓakar sarkar mai girma amma sabbin hanyoyin kai hari).

3.3 Matsalar Tsaro: "Lada ga Mugunta" da "Hukunci ga Nagarta"

Binciken ya gano matsala ta asali a cikin ƙirar PoW. Yarjejeniyoyin da suke hukunta ayyukan mugunta da aka ɗauka (misali, yin maraya ga tubalan) sau da yawa suna ƙarewa da hukunta ma'adinan gaskiya da suka kama cikin jinkirin cibiyar sadarwa, suna rage lada ɗinsu kuma suna hana shiga. Akasin haka, yarjejeniyoyin da suka yi sassauci sosai ga reshe don adana duk aikin ("lada ga mugunta") suna ƙarfafa hako ma'adinai na son kai. Wannan ciniki shine babban cikas ga cikakken tsaro.

4. Cikakkun Bayanai na Fasaha & Tsarin Lissafi

Kimantawa ya dogara ne akan samfurin Markov inda jihohi ke wakiltar jagorancin reshen sirri na mai yuwuwar mahari akan sarkar jama'a. Yiwuwar canzawa ayyuka ne na rarraba ƙarfin hash $\alpha$ (mahari) da $1-\alpha$ (gaskiya), da ƙa'idodin yarjejeniya na zaɓin sarkar da lada na tubalan.

Mahimmin Tsari (Nasarar Kai Hari Gabaɗaya): Yiwuwar $P_{\text{success}}$ na mahari mai ƙarfin hash $\alpha$ ya kama daga rashi na tubalan $z$, kamar yadda yake a yunƙurin kashe kuɗi sau biyu, ana bayar da shi ta: $$P_{\text{success}}(\alpha, z) = \begin{cases} 1 & \text{idan } \alpha > 0.5 \\ (\frac{\alpha}{1-\alpha})^z & \text{idan } \alpha < 0.5 \end{cases}$$ Wannan tsari na gargajiya (daga takardar farar Bitcoin ta S. Nakamoto) an gyara shi a cikin tsarin don lissafin karkatattun yarjejeniyoyi daga ƙa'idar sarkar mafi tsawo ta NC, wanda ke canza ingantaccen yanayin "tsere".

5. Sakamakon Gwaji & Hare-haren da suka shafi Yarjejeniya

Binciken Markov ba wai kawai ya tabbatar da hare-haren da aka sani ba amma ya bayyana sabbin dabarun kai hari na musamman ga yarjejeniya.

Ga Ethereum/GHOST: Tsarin ya gano yanayin da za a iya yin wasa da ƙa'idar "Greediest Heaviest Observed SubTree" ta hanyar sakin tubalan da dabara don sarrafa nauyin reshe, wanda zai iya taimakawa hako ma'adinai na son kai.
Ga Bitcoin-NG: Rarraba tubalan maɓalli (don zaɓen shugaba) da ƙananan tubalan (don ma'amaloli) yana gabatar da sabbin hanyoyin kai hari na tushen jinkiri inda mahari zai iya rufe shugaba kuma ya takunkumi ƙananan tubalansa.
Hankali na Ginshiƙi: Zanen da aka yi kwaikwayo zai nuna ingancin sarkar (y-axis) na yarjejeniyoyi daban-daban (x-axis) a matsayin aiki na ƙarfin hash na mahari $\alpha$ (layi daban-daban). Babban abin da za a ɗauka: duk layukan yarjejeniya sun faɗi ƙasa da layin da ake so na $CQ = 1-\alpha$, musamman yayin da $\alpha$ ke kusanci da 0.3-0.4.

6. Tsarin Bincike: Misalin Nazarin Shari'a

Shari'a: Kimanta wata yarjejeniyar "FastChain" ta zato wacce ke da'awar juriya ga hako ma'adinai na son kai.

Ayyana Ma'auni: Aiwatar da ma'auni huɗu na asali. Don FastChain, muna buƙatar ainihin jadawalin lada na tubalan, ƙa'idar zaɓin sarkar, da manufar marayu.
Samfurin azaman Tsarin Markov: Jihohi = (jagorancin reshen sirri, matsayin reshen jama'a). Canje-canje sun dogara da ƙa'idodin FastChain don sarrafa daidaito da lada ga tubalan da suka tsufa.
Lissafin Matsayin Kwanciyar hankali:
Samun Ingancin Sarkar: Daga matsakaicin yanayi, lissafa yawan lokacin da ake tsammanin na tubalan akan sarkar da aka saba da ma'adinan gaskiya suka haƙa. Wannan shine $CQ$ na yarjejeniyar.

Gwada Juriyar Kai Hari: Yi kwaikwayon dabarar ma'adinan son kai a cikin samfurin. Shin kudaden shiga na mahari ya wuce $\alpha$? Idan $\text{Revenue}_{\text{mahari}} > \alpha$, yarjejeniyar ta kasa gwajin daidaitawar ƙarfafawa don wannan hari.

Ƙarshe: Ba tare da lambar ba, wannan tsari mai tsari yana tilasta ingantaccen kimantawa na ƙididdiga wanda zai iya karyata ko tabbatar da da'awar tsaro.

7. Hanyoyin Gaba & Hasashen Aikace-aikace

Takardar ta zayyana mahimman hanyoyi don bincike da ƙira na PoW na gaba:

Motsawa Bayan Zato maras Gaskiya: Yarjejeniyoyin na gaba dole ne su yi samfuri a sarari kuma su ƙera don jinkirin cibiyar sadarwa (aiki tare) da ma'adinan masu hankali (ba kawai gaskiya ba) tun daga farko, kamar yadda aka jaddada a cikin aikin ingantaccen daidaitawar ƙarfafawa.

Samfuran Yarjejeniya na Gauraye: Bincika gaurayawan masu amfani, kamar PoW don zaɓen shugaba haɗe da ingantaccen yarjejeniya irin na BFT (misali, kamar yadda aka bincika a ayyuka kamar Thunderella) don ƙaddamar da tubalan, zai iya rage kurakuran ingancin PoW.

Tabbatarwa na Yau da kullun & Ma'auni na Daidaitacce: Tsarin da aka gabatar ya kamata ya rikiɗe zuwa daidaitaccen jerin ma'auni. Ana iya buƙatar sabbin yarjejeniyoyi su buga sakamakon binciken Markov ɗinsu, kama da yadda algorithms ɓoyayyen bayanai ke buga hujjojin tsaro.

Aikace-aikace a cikin Binciken Tsaro: Wannan tsarin yana da amfani kai tsaye ga kamfanonin binciken tsaro na blockchain da masu bincike da ke kimanta sabbin sarƙoƙi na Layer 1 ko manyan haɓaka yarjejeniya (misali, canjin Ethereum).

8. Nassoshi

Nakamoto, S. (2008). Bitcoin: Tsarin Kuɗin Lantarki na Peer-to-Peer.

Eyal, I., & Sirer, E. G. (2014). Rinjaye bai isa ba: Hako ma'adinan Bitcoin yana da rauni. A cikin Cryptography na Kuɗi.

Sompolinsky, Y., & Zohar, A. (2015) Tsarin ma'amala mai sauri mai tsaro a cikin Bitcoin. A cikin Cryptography na Kuɗi.

Pass, R., Seeman, L., & Shelat, A. (2017). Binciken yarjejeniyar blockchain a cikin hanyoyin sadarwa marasa aiki tare. A cikin Eurocrypt.

Buterin, V. (2014). Ethereum: Dandalin Kwangilar Wayo na Gaba da Dandalin Aikace-aikace mai Rarrabuwa.

Kiayias, A., et al. (2016). Ouroboros: Yarjejeniyar Blockchain mai Tabbacin Tsaro ta Hujjar Hatsari. A cikin Crypto. [Tushen Waje - Misalin nazarin madadin yarjejeniya]

Jaridar IEEE Access akan Tsaro & Sirrin Blockchain.

9. Bincike na Asali & Sharhin Kwararru

Hankali na Asali

Aikin Zhang da Preneel shine sake duba gaskiyar gaskiya ga masana'antar blockchain. Yana rushewa tsarin tallan tallan da ke kewaye da yarjejeniyoyin PoW na "zamanin gaba". Gaskiyar asali, mara daɗi da suka fallasa ita ce duk bambance-bambancen PoW na yanzu suna ciniki da juna na kurakuran tsaro. Babu abincin kyauta. Neman cikakkiyar ingancin sarkar a ƙarƙashin cikakken samfurin adawa na hankali, mai kama da Matsalar Janar na Byzantine - na iya zama ba zai yiwu ba na lissafi ga PoW mai tsabta, wani zato da aka maimaita a cikin adabin kwamfuta mai rarrabuwa na asali.

Kwararar Hankali

Hankalin takardar ba shi da aibi: 1) Ware tushen dalili (ingancin sarkar mara kyau), 2) Gina tsarin ƙididdiga don auna shi da sakamakonsa, 3) Aiwatar da shi cikin tsananin gaske ga duk manyan masu fafatawa, 4) Gano gazawar duniya. Wannan hanyar tana da fifiko fiye da binciken da ya keɓance ga kai hari wanda ya mamaye fagen. Ta hanyar tsara matsalar azaman Tsarin Yanke Shawara na Markov, sun kawo ƙaƙƙarfan samfurin bazuwar zuwa sarari mai cike da da'awar da ba za a iya gano su ba.

Ƙarfi & Kurakurai

Ƙarfi: Tsarin kansa shine babbar gudummawar takardar. Yana ba al'umma harshe da kayan aiki guda ɗaya, kamar yadda ka'idar CAP ta yi wa bayanan bayanai masu rarrabuwa. Gano "matsalar lada da hukunci" wani babban tsalle ne na ra'ayi wanda ke bayyana dalilin da yasa gyare-gyaren yarjejeniya sau da yawa ke komawa baya.
Kurakurai/Rashin: Binciken, ko da yake yana da zurfi, galibi na ka'ida ne. Zai amfana da bayanan kwaikwayon babban cibiyar sadarwa don tabbatar da samfuran Markov a ƙarƙashin yanayin duniya na gaske kamar rarraba ƙarfin hash na yanki da tsarin jinkiri na Intanet. Bugu da ƙari, ya taƙaice amma ya yi ƙasa da ƙarfin kudin makamashi na PoW a matsayin damuwa na tsaro-tsaro. Yarjejeniyar da ta fi tsaro kashi 10 cikin ɗari amma tana cinye ƙarin makamashi kashi 50 cikin ɗari nasara ce mai wahala, wani batu da ƙungiyoyi kamar Hukumar Makamashi ta Duniya suka yi muhawara a cikin rahotanninsu kan tasirin muhalli na cryptocurrency.

Hankali mai Aiki

Ga masu aiki, wannan takarda wajibi ce a karanta. 1) Masu Zuba Jari & Masu Haɓakawa: Bincika kowane da'awar yarjejeniyar PoW ta wannan ruwan tabarau na ma'auni huɗu. Nemi binciken Markov. 2) Masu Bincike: Gaba yana cikin samfuran gauraye ko bayan PoW a sarari. Ya kamata fagen ya saka ƙasa da goge tagulla na PoW kuma ya fi yawa a cikin yarjejeniyoyi kamar Ouroboros (PoS) ko HoneyBadgerBFT (BFT maras aiki tare), waɗanda suka fara daga zato daban-daban, masu sauƙin sarrafawa. 3) Ƙungiyoyin Ma'auni (misali, IEEE, W3C): Wannan tsarin ya kamata ya zama tushen daidaitaccen takardar shedar tsaro na blockchain. A cikin masana'antar da ke fama da yawan alkawura, wannan aikin yana ba da kayan aiki don ingantaccen tsari da lissafi.