1. Gabatarwa & Bayyani

Wannan takarda ta gabatar da kuma bincika Harin Daidaitawa, wani sabon yaudara na tsaro da ke kaiwa ga yarjejeniyar tsarin blockchain na Proof-of-Work (PoW), tare da mai da hankali musamman kan Ethereum da tsarinta na GHOST. Ba kamar harin na gargajiya na 51% da ke buƙatar ƙarfin lissafi mai ƙarfi ba, Harin Daidaitawa yana amfani da dabarun jinkirin sadarwar cibiyar sadarwa tsakanin ƙungiyoyin ƙananan na'urori don ƙirƙirar rarrabuwa na ɗan lokaci, yana ba da damar kashe kuɗi sau biyu tare da ƙaramin ƙarfin ma'adinai. Binciken ya ba da tsarin ka'idar matsakaicin yiwuwa da kuma tabbatarwa ta gwaji ta amfani da saitin da ke kwatanta gwajin blockchain na ƙungiyar kuɗi ta R3.

Babban binciken shine cewa tsarin blockchain na PoW, musamman waɗanda ke amfani da tsarin lissafin toshe na kawu kamar GHOST, ƙila ba su dace da tsarin haɗin gwiwa ko tsarin sirri ba inda za a iya sarrafa tsarin cibiyar sadarwa da jinkiri ko kuma a iya hasashensu.

2. Tsarin Harin Daidaitawa

Harin yana amfani da dabarar warware rarrabuwar blockchain ta hanyar ƙirƙirar yanayin cibiyar sadarwa na wucin gadi wanda ke haifar da sarƙoƙi masu gasa daidai da nauyi.

2.1 Ka'idar Harin Ta Asali

Mai harin ya raba cibiyar sadarwa zuwa (aƙalla) ƙungiyoyin ƙananan biyu tare da matsakaicin ƙarfin ma'adinai daidai gwargwado. Ta hanyar jinkirta saƙonni a zaɓaɓɓe tsakanin waɗannan ƙungiyoyin ƙananan (amma ba a cikinsu ba), mai harin yana barin su su yi ma'adinai akan sarƙoƙi daban-daban. Sa'an nan mai harin ya mai da hankali kan ƙarfinsa na ma'adinai akan ɗaya ƙungiyar ƙaramar (ƙungiyar ƙaramar toshi), yayin da yake fitar da ma'amaloli da yake niyyar juyar da su a ɗayan (ƙungiyar ƙaramar ma'amala).

2.2 Matakan Harin

  1. Rarrabuwa & Jinkiri: Mai harin ya ware ƙungiyoyin ƙananan A da B ta hanyar jinkirin cibiyar sadarwa.
  2. Ma'adinan Layi Daya: Ƙungiyoyin ƙananan A da B suna gina sarƙoƙi daban-daban. Mai harin yana yin ma'adinai ne kawai tare da ƙungiyar ƙaramar B.
  3. Fitowar Ma'amala: Mai harin ya fitar da ma'amala a cikin ƙungiyar ƙaramar A, wanda aka tabbatar a cikin sarkarta.
  4. Karkatar da Nauyi: Mai harin ya ci gaba da yin ma'adinai a cikin ƙungiyar ƙaramar B har sai yiwuwar cewa sarkar B (ciki har da toshe na kawu) ta fi nauyin sarkar A ya yi yawa.
  5. Haɗawa Sake & Sake Tsari: Mai harin ya dakatar da jinkirin. Lokacin da cibiyar sadarwa ta daidaita ra'ayoyi ta amfani da GHOST, an karɓi sarkar mafi nauyi daga ƙungiyar ƙaramar B, ya bar toshe mai ɗauke da ma'amalar mai harin kuma ya ba da damar kashe kuɗi sau biyu.

3. Bincike na Ka'idar & Tsari

Takardar ta kafa tsarin matsakaicin yiwuwa na yau da kullun don tantance sharuɗɗan harin mai nasara.

3.1 Tsarin Matsakaicin Yiwuwa

Binciken yana amfani da iyakar Chernoff don ƙirƙirar tsarin ma'adinai azaman tsarin Poisson. Muhimmin ma'auni shine lokacin jinkiri ($\Delta$) da mai harin dole ne ya kiyaye daidai da kaso na ƙarfin ma'adinai na mai harin ($\alpha$) da ƙarfin cibiyar sadarwa ta gaskiya.

3.2 Muhimmin Tsarin Lissafi

An samo yiwuwar cewa reshen mai harin a cikin ƙungiyar ƙaramar da aka ware ya zama mafi nauyi fiye da reshen ɗayan ƙungiyar ƙaramar. Don kashe kuɗi sau biyu mai nasara tare da babban yiwuwa, jinkirin da ake buƙata $\Delta$ yana da alaƙa da juzu'i da ƙarfin ma'adinai na mai harin. Tsarin ya ɗauki ciniki: ƙaramin ƙarfin mai harin yana buƙatar tsawon jinkirin cibiyar sadarwa. Bayani mai sauƙi don tsammanin jagoranci $L$ da mai harin zai iya samu a cikin lokaci $t$ tare da ƙarfin hash $q$ a kan ƙarfin gaskiya $p$ yana da alaƙa da ƙimar tsarin Poisson: $\lambda = \frac{p}{\tau}$, inda $\tau$ shine lokacin toshe. Ci gaban mai harin shine ma'auni na bazuwar da aka ƙirƙira ta wannan tsari.

4. Tabbatarwa ta Gwaji

An gwada tsarin ka'idar a cikin yanayi na aiki wanda aka ƙirƙira bayan ƙungiyar haɗin gwiwa ta R3.

4.1 Saitin Gwajin Ƙungiyar R3

An tura sarkar sirri ta Ethereum a cikin tsarin rarraba da ke kwatanta yanayin ƙungiyar haɗin gwiwa ta R3 (kimanin bankuna 11 masu shiga). An gabatar da jinkirin cibiyar sadarwa da gangan tsakanin ƙungiyoyin ƙananan na'urori don kwaikwayi harin.

4.2 Sakamako & Yiwuwar Harin

Muhimmin Binciken Gwaji

Tsawon Harin: Na'ura guda ɗaya ta sami nasarar aiwatar da Harin Daidaitawa a kan ƙungiyar haɗin gwiwa ta R3 da aka kwaikwayi a cikin kusan minti 20.

Tasiri: Wannan yana nuna cewa harin ba ka'idar kawai ba ne amma yana yiwuwa a aikace tare da ƙananan albarkatu a cikin tsarin haɗin gwiwa, inda jimillar ƙarfin hash na cibiyar sadarwa ya iyakance idan aka kwatanta da manyan hanyoyin sadarwa na jama'a.

Bayanin Chati (Ra'ayi): Chati na layi zai nuna yiwuwar nasarar kashe kuɗi sau biyu (Y-axis) yana tashi da sauri yayin da lokacin jinkiri da mai harin ke sarrafawa (X-axis) ya ƙaru, har ma ga ƙananan ƙimar ƙarfin ma'adinai na mai harin (wanda aka wakilta ta layukan daban-daban). Lanƙwasa ga mai harin na 20% zai kai ga babban yiwuwa da sauri fiye da na mai harin na 5%, amma dukansu a ƙarshe sun yi nasara idan aka ba da isasshen jinkiri.

5. Tasiri & Bincike na Kwatance

5.1 Raunin Ethereum da Bitcoin

Duk da yake dukansu suna da rauni ga harin matakin cibiyar sadarwa, takardar ta nuna cewa tsarin GHOST na Ethereum, wanda ya haɗa toshe na kawu cikin lissafin nauyi, ƙila ya haifar da wani filin harin daban. Harin Daidaitawa musamman yana sarrafa ka'idar "reshe mafi nauyi" ta hanyar ƙirƙirar daidaitattun reshe masu gasa ta hanyar warewa. Ka'idar sarkar mafi tsayi ta Bitcoin tana da rauni ga harin jinkiri daban-daban (misali, ma'adinan son kai), amma an tsara Harin Daidaitawa a kusa da injiniyoyin GHOST.

5.2 Dacewar Tsarin Blockchain na Haɗin Gwiwa

Matsalar da takardar ta yi shi ne cewa tsarin PoW na asali ba su dace da tsarin blockchain na haɗin gwiwa ba. Ƙungiyoyin haɗin gwiwa suna da ƴan mahalarta, sanannun mahalarta, suna sa harin rarrabuwar cibiyar sadarwa su zama mafi yuwuwa fiye da akan cibiyar sadarwa ta duniya, mai adawa da Bitcoin. Ƙarancin jimillar ƙarfin hash kuma yana rage farashin samun wani yanki mai ma'ana.

6. Ra'ayi na Mai Bincike: Fahimta ta Asali & Zargi

Fahimta ta Asali: Natoli da Gramoli sun fallasa wani muhimmin ka'ida, sau da yawa ana yin watsi da shi a cikin tsaron blockchain: tsaron yarjejeniya aiki ne na hujja na sirri da kuma daidaitawar cibiyar sadarwa. Harin Daidaitawa ba game da karya SHA-256 ko Ethash ba ne; yana game da karya "zanuwar cibiyar sadarwa" a cikin samfuran da ba su da daidaituwa. Wannan yana motsa barazana daga matakin lissafi (ƙarfin hash) zuwa matakin cibiyar sadarwa (hanyoyin sadarwa, ISPs), wani iyaka da yawancin masu sarrafa ƙungiyoyin haɗin gwiwa ba su shirya don karewa ba. Yana maimaita darussan daga tsarin rarraba na gargajiya kamar sakamakon rashin yiwuwar FLP, yana tabbatar da cewa yarjejeniya tana da rauni a ƙarƙashin rashin daidaituwa.

Tsarin Ma'ana: Hujja tana da kyau a cikin sauƙinta. 1) Tsaron PoW ya dogara da sarkar guda, mafi saurin girma. 2) GHOST ya canza wannan zuwa sarkar "mafi nauyi", yana haɗa kawu don inganta kwarara. 3) Ta hanyar ƙirƙirar rarrabuwa tare da daidaitaccen ƙarfi, mai harin ya tilasta ƙirƙirar reshe biyu masu nauyi, ingantattu. 4) Bayan sake haɗawa, ka'idar GHOST ta zama hanyar harin, ba kariya ba. Kuskuren ma'ana da yake amfani da shi shine cewa GHOST yana ɗauka nauyin yana nuna aikin gaskiya, amma a cikin cibiyar sadarwa da aka raba, nauyin yana nuna aikin ware, wanda za a iya sarrafa shi.

Ƙarfi & Kurakurai: Ƙarfin takardar shine nunin aikace-aikacen ta akan sarkar sirri ta Ethereum, yana motsawa fiye da ka'idar. Amfani da iyakokin Chernoff yana ba da ƙwaƙƙwaran lissafi. Duk da haka, binciken yana da aibi na gama gari a cikin takardun tsaro na ilimi: yana ɗauka cewa kusan cikakke ne, ci gaba da rarrabuwar cibiyar sadarwa. A cikin cibiyoyin sadarwar kamfani na ainihi tare da hanyoyi na zahiri da na hankali da yawa, kiyaye irin wannan tsabtataccen rarrabuwa na fiye da minti 20 a kan sa ido na injiniyoyin cibiyar sadarwa ba abu ne mai sauƙi ba. Harin kuma yana buƙatar mai harin ya gano kuma ya yi niyya ga ƙungiyoyin ƙananan tare da daidaitaccen ƙarfin hash daidai, wanda ƙila zai buƙaci ilimin ciki a cikin ƙungiyar haɗin gwiwa.

Fahimta Mai Aiki: Ga kowane kamfani da ke la'akari da sarkar haɗin gwiwa na tushen PoW, wannan takarda ce tuta ja tilas. Abin da za a yi nan take shi ne yin watsi da PoW mai tsabta don saitunan haɗin gwiwa. Madadin kamar Proof-of-Authority (PoA), Practical Byzantine Fault Tolerance (PBFT), ko abubuwan da suka samo asali daga gare su (kamar Istanbul BFT) sun fi juriya a asali saboda tsaronsu ya samo asali ne daga ainihi da watsa saƙo, ba ƙarfin hash da sa'ar cibiyar sadarwa ba. Don sarƙoƙi na jama'a kamar Ethereum, ragewa yana ta'allaka ne a cikin ingantaccen tsarin cibiyar sadarwa mara tsari (kamar Discv5 na Ethereum) da saurin yaduwar toshe (kamar Graphene). Sa ido kan cibiyar sadarwa don jinkiri na sabani tsakanin manyan tafkunan ma'adinai ya kamata ya zama aikin tsaro na yau da kullun. Wannan binciken, tare da aikin farko akan harin kusufin rana (Heilman et al.) da harin cin hanci (Judmayer et al.), sun zama gurɓataccen shaida cewa dole ne a ƙirƙira yarjejeniyar Layer-1 tare da ƙayyadadden samfuran cibiyar sadarwa na adawa a zuciya.

7. Zurfin Binciken Fasaha

7.1 Cikakkun Bayanai na Tsarin Lissafi

An ƙirƙira tsarin ma'adinai don na'urori masu gaskiya da mai harin azaman tsarin Poisson masu zaman kansu tare da ƙima $\lambda_h$ da $\lambda_a$, bi da bi, inda $\lambda = \text{ƙarfin hash} / \text{lokacin toshe}$. Bari $Q(t)$ da $H(t)$ su zama adadin tubalan da mai harin da cibiyar sadarwa ta gaskiya suka yi ma'adinai a cikin lokaci $t$. Tsammaninsu shine $\mathbb{E}[Q(t)] = \lambda_a t$ da $\mathbb{E}[H(t)] = \lambda_h t$.

Manufar mai harin a lokacin lokacin jinkiri $\Delta$ ita ce kafa jagoranci $z$ a cikin wani yanki. Yiwuwar cewa sarkar mai harin a cikin yanki B ta kasance aƙalla $k$ tubalan a gaban sarkar gaskiya a cikin yanki A ana iya iyakance ta ta amfani da rashin daidaiton wutsiya don rarraba Poisson. Sharadin nasarar harin lokacin da cibiyoyin sadarwa suka haɗu ya haɗa da kwatanta jimillar nauyin (ciki har da kawu) na sarƙoƙi biyu masu gasa. Takardar ta samo sharadi mai haɗa $\Delta$, $\alpha$ (kaso na mai harin na jimillar ƙarfi), da yiwuwar nasara da ake so.

7.2 Ma'auni na Gwaji & Ma'auni

  • Gwajin Gwaji: Cibiyar sadarwar sirri ta Ethereum (abokan cinikin Geth).
  • Ƙidaya Node: An ƙirƙira akan mahalartan R3 ~11.
  • Kwaikwayon Cibiyar Sadarwa: An yi amfani da kayan aiki (misali, `tc` netem) don gabatar da daidaitaccen jinkiri ($\Delta$) tsakanin ƙungiyoyin ƙananan na'urori.
  • Rarraba Ƙarfin Ma'adinai: An kwaikwayi ƙungiyoyin ƙananan masu daidaito (misali, 45%-45% gaskiya, 10% mai harin).
  • Ma'auni na Farko: Lokaci-zuwa-nasara-kashe-kuɗi-sau-biyu (TTS) da yiwuwarsa.
  • Tabbatarwa: An maimaita gudu don auna daidaiton lokacin harin na kusan minti 20.

8. Tsarin Bincike & Misali na Ra'ayi

Yanayi: Tsarin blockchain na haɗin gwiwa don kuɗin kasuwanci tare da bankuna 10, kowannensu yana aiki da na'urar ma'adinai ɗaya daidai da ƙarfi.

Aiwatar da Tsarin Harin:

  1. Bincike: Mai harin (mai mugun nufi a wani banki) ya zana taswirar tsarin cibiyar sadarwa kuma ya gano cewa an kwashe na'urori a cikin manyan yankuna guda biyu na girgije: US-East (na'urori 6) da EU-West (na'urori 4).
  2. Daidaita Ƙarfi: Mai harin ya lissafta cewa ƙungiyar ƙaramar US-East tana da ~60% na ƙarfin hash kuma EU-West tana da ~40%. Don daidaitawa, mai harin ya lalata ko ya kawo wani ƙarin node a yankin EU na ɗan lokaci, yana daidaita ma'auni kusa da 50%-50%.
  3. Rarrabuwa: Ta amfani da satar BGP ko kai hari na DDoS akan hanyoyin haɗin yanki, mai harin ya haifar da jinkirin sadarwa na minti 30 tsakanin US-East da EU-West.
  4. Aiwatarwa: Mai harin ya fitar da ma'amala don siyan kadarori a cikin sarkar US-East. A lokaci guda, suna yin ma'adinai tare da albarkatunsu a cikin yankin EU-West. Bayan mintuna 25, sarkar EU-West (wanda aka ƙarfafa ta hanyar ma'adinan mai harin) tana da nauyin GHOST mafi nauyi.
  5. Warwarewa: Mai harin ya dakatar da tsangwamar cibiyar sadarwa. Na'urorin cibiyar sadarwa sun daidaita kuma sun karɓi sarkar EU-West, suna soke ma'amalar US-East. Mai harin ya kashe kadarorin sau biyu.

Wannan misalin da ba na lamba ba yana kwatanta matakan harin ta amfani da yanayin kasuwanci na ainihi.

9. Hanyoyin Gaba & Dabarun Ragewa

  • Juyin Halitta na Yarjejeniya: Ƙarin karɓuwar yarjejeniyar da ba ta PoW ba don sarƙoƙi na sirri/haɗin gwiwa (misali, Raft na Hyperledger Fabric, QBFT na Quorum).
  • Samfuran Haɗin Kai: Bincike cikin tsarin PoW waɗanda ke da haƙuri na jinkiri a fili ko waɗanda suka haɗa da hujjojin jinkirin cibiyar sadarwa.
  • Ƙarfafa Tsaron Matakin Cibiyar Sadarwa: Haɗa tsarin cibiyar sadarwa na abokan aikinta tare da fasalulluka masu hana rarrabuwa, kamar zaɓin abokan aikinta na bazuwar da za a iya tabbatar da su da sa ido kan ƙirar jinkiri na sabani.
  • Tabbatarwa na Yau da Kullun: Yin amfani da hanyoyin na yau da kullun don ƙirƙira da tabbatar da yarjejeniyar ƙarƙashin zato na daidaitawar cibiyar sadarwa mai rauni, kama da aikin da aka yi akan yarjejeniyar Algorand.
  • Mai da Hankali kan Tsari & Mulki: Don ƙungiyoyin haɗin gwiwa, haɓaka samfuran mulki da ƙa'idodin fasaha waɗanda ke tilasta ingantaccen tsarin cibiyar sadarwa da sa ido a matsayin wani ɓangare na turawar blockchain, ba bayan tunani ba.

10. Nassoshi

  1. Natoli, C., & Gramoli, V. (2016). The Balance Attack Against Proof-Of-Work Blockchains: The R3 Testbed as an Example. arXiv preprint arXiv:1612.09426.
  2. Nakamoto, S. (2008). Bitcoin: A Peer-to-Peer Electronic Cash System.
  3. Buterin, V. (2014). Ethereum: A Next-Generation Smart Contract and Decentralized Application Platform.
  4. Sompolinsky, Y., & Zohar, A. (2013). Accelerating Bitcoin's Transaction Processing. Fast Money Grows on Trees, Not Chains. IACR Cryptology ePrint Archive.
  5. Heilman, E., Kendler, A., Zohar, A., & Goldberg, S. (2015). Eclipse Attacks on Bitcoin's Peer-to-Peer Network. USENIX Security Symposium.
  6. Eyal, I., & Sirer, E. G. (2014). Majority is not Enough: Bitcoin Mining is Vulnerable. International Conference on Financial Cryptography and Data Security.
  7. Lamport, L., Shostak, R., & Pease, M. (1982). The Byzantine Generals Problem. ACM Transactions on Programming Languages and Systems.
  8. Castro, M., & Liskov, B. (1999). Practical Byzantine Fault Tolerance. OSDI.