Most blockchains are designed as a decentralized database that functions as a distributed digital ledger. These blockchain ledgers record and store data in blocks, which are organized in a chronological sequence and are linked through cryptographic proofs. The creation of blockchain technology brought up many advantages in a variety of industries, providing increased security in trustless environments. However, its decentralized nature also brings some disadvantages. For instance, when compared to traditional centralized databases, blockchains present limited efficiency and require increased storage capacity.
Since blockchain data is often stored in thousands of devices on a distributed network of nodes, the system and the data are highly resistant to technical failures and malicious attacks. Each network node is able to replicate and store a copy of the database and, because of this, there is no single point of failure: a single node going offline does not affect the availability or security of the network.
In contrast, many conventional databases rely on a single or a few servers and are more vulnerable to technical failures and cyber-attacks.
Confirmed blocks are very unlikely to be reversed, meaning that once data has been registered into the blockchain, it is extremely difficult to remove or change it. This makes blockchain a great technology for storing financial records or any other data where an audit trail is required because every change is tracked and permanently recorded on a distributed and public ledger.
For example, a business could use blockchain technology to prevent fraudulent behavior from its employees. In this scenario, the blockchain could provide a secure and stable record of all financial transactions that take place within the company. This would make it much harder for an employee to hide suspicious transactions.
In most traditional payment systems, transactions are not only dependent on the two parties involved, but also on an intermediary – such as a bank, credit card company, or payment provider. When using blockchain technology, this is no longer necessary because the distributed network of nodes verify the transactions through a process known as mining. For this reason, Blockchain is often referred to as a ‘trustless’ system.
Therefore, a blockchain system negates the risk of trusting a single organization and also reduces the overall costs and transaction fees by cutting out intermediaries and third parties.
The Proof of Work consensus algorithm that protects the Bitcoin blockchain has proven to be very efficient over the years. However, there are a few potential attacks that can be performed against blockchain networks and 51% attacks are among the most discussed. Such an attack may happen if one entity manages to control more than 50% of the network hashing power, which would eventually allow them to disrupt the network by intentionally excluding or modifying the ordering of transactions.
Despite being theoretically possible, there was never a successful 51% attack on the Bitcoin blockchain. As the network grows larger the security increases and it is quite unlikely that miners will invest large amounts of money and resources to attack Bitcoin as they are better rewarded for acting honestly. Other than that, a successful 51% attack would only be able to modify the most recent transactions for a short period of time because blocks are linked through cryptographic proofs (changing older blocks would require intangible levels of computing power). Also, the Bitcoin blockchain is very resilient and would quickly adapt as a response to an attack.
Another downside of blockchain systems is that once data has been added to the blockchain it is very difficult to modify it. While stability is one of blockchain’s advantages, it is not always good. Changing blockchain data or code is usually very demanding and often requires a hard fork, where one chain is abandoned, and a new one is taken up.
Blockchain uses public-key (or asymmetric) cryptography to give users ownership over their cryptocurrency units (or any other blockchain data). Each blockchain address has a corresponding private key. While the address can be shared, the private key should be kept secret. Users need their private key to access their funds, meaning that they act as their own bank. If a user loses their private key, the money is effectively lost, and there is nothing they can do about it.
Blockchains, especially those using Proof of Work, are highly inefficient. Since mining is highly competitive and there is just one winner every ten minutes, the work of every other miner is wasted. As miners are continually trying to increase their computational power, so they have a greater chance of finding a valid block hash, the resources used by the Bitcoin network has increased significantly in the last few years, and it currently consumes more energy than many countries, such as Denmark, Ireland, and Nigeria.
Blockchain ledgers can grow very large over time. The Bitcoin blockchain currently requires around 200 GB of storage. The current growth in blockchain size appears to be outstripping the growth in hard drives and the network risks losing nodes if the ledger becomes too large for individuals to download and store.
Despite the downsides, blockchain technology presents some unique advantages, and it is definitely here to stay. We still have a long road to mainstream adoption, but many industries are getting to grips with the advantages and disadvantages of blockchain systems. The next few years will likely see businesses and governments experimenting with new applications to find out where blockchain technology adds the most value.
Blockchain ni mfumo wa kuunganisha na kuunganisha data ya decentralized ambayo hufanya kazi kama ledger ya digital. Blockchain ledgers kurekodi na kuhifadhi data katika vitalu, ambayo ni kupangwa katika mfululizo wa muda na ni kushikamana kupitia uthibitisho cryptographic. Uundaji wa teknolojia ya blockchain ulileta faida nyingi katika tasnia mbalimbali, ikitoa usalama ulioongezeka katika mazingira yasiyo ya uaminifu. Hata hivyo, asili yake ya kutokuwa na mamlaka pia huleta hasara fulani. Kwa mfano, ikilinganishwa na hifadhidata za jadi za kituo, blockchains zina ufanisi mdogo na zinahitaji uwezo mkubwa wa kuhifadhi. Kwa kuwa data ya blockchain mara nyingi huhifadhiwa katika maelfu ya vifaa kwenye mtandao uliosambazwa wa nodes, mfumo na data ni sugu sana kwa kushindwa kwa kiufundi na mashambulizi mabaya. Kila node ya mtandao ina uwezo wa kuiga na kuhifadhi nakala ya hifadhidata, na kwa sababu hii, hakuna hatua moja ya kushindwa: node moja kwenda nje ya mtandao haina kuathiri upatikanaji au usalama wa mtandao. Kinyume chake, hifadhidata nyingi za kawaida hutegemea seva moja au chache na ni dhaifu zaidi kwa kushindwa kwa kiufundi na mashambulizi ya mtandao. Blocks kuthibitishwa ni uwezekano mdogo sana kuwa reversed, maana kwamba mara moja data imekuwa kusajiliwa katika blockchain, ni vigumu sana kuondoa au kubadilisha. Hii inafanya blockchain teknolojia kubwa kwa ajili ya kuhifadhi rekodi za kifedha au data nyingine yoyote ambapo kufuatilia kufuatilia inahitajika kwa sababu kila mabadiliko ni kufuatiliwa na kudumu kumbukumbu juu ya usambazaji na umma ledger. Kwa mfano, biashara inaweza kutumia teknolojia ya blockchain kuzuia tabia ya udanganyifu kutoka kwa wafanyikazi wake. Katika hali hii, blockchain inaweza kutoa rekodi salama na imara ya shughuli zote za kifedha ambazo hufanyika ndani ya kampuni. Hilo lingefanya iwe vigumu zaidi kwa mfanyakazi kuficha shughuli zenye kutilika shaka. Katika mifumo mingi ya malipo ya jadi, shughuli si tu hutegemea pande mbili zinazohusika, lakini pia juu ya mpatanishi - kama vile benki, kampuni ya kadi ya mkopo, au mtoa huduma ya malipo. Wakati wa kutumia teknolojia ya blockchain, hii si muhimu tena kwa sababu mtandao wa nodes kusambazwa kuthibitisha shughuli kupitia mchakato unaojulikana kama madini. Kwa sababu hii, Blockchain ni mara nyingi inajulikana kama "trustless" mfumo. Kwa hiyo, mfumo wa blockchain hupunguza hatari ya kuamini shirika moja na pia hupunguza gharama za jumla na ada za shughuli kwa kukata waingiliaji na watu wa tatu. Algorithm ya Proof-of-Work (PWT) ambayo inahifadhi blockchain ya Bitcoin imethibitishwa kuwa na ufanisi mkubwa. Hata hivyo, kuna mashambulizi ya uwezekano wa kuwa na uwezo wa kutekelezwa dhidi ya mitandao ya blockchain, na mashambulizi ya 51% ni miongoni mwa zaidi kujadiliwa. Shambulio kama hilo linaweza kutokea ikiwa chombo kimoja kinashinda kudhibiti zaidi ya 50% ya nguvu ya hashing ya mtandao, ambayo hatimaye itawawezesha kuvuruga mtandao kwa kuondoa au kurekebisha utaratibu wa shughuli. Ingawa ni uwezekano wa kiakili, hakuna mashambulizi ya 51% ya mafanikio yaliyotokea kwenye blockchain ya Bitcoin. Kadiri mtandao unavyoongezeka, usalama unaongezeka, na ni uwezekano mdogo kwamba wachimbaji watawekeza pesa nyingi na rasilimali kushambulia Bitcoin, kwani wanatozwa vizuri kwa kutenda kwa uaminifu. Kwa upande mwingine, shambulio la 51% la mafanikio litabadilisha tu shughuli za hivi karibuni kwa muda mfupi kwa sababu vitalu vimeunganishwa kupitia uthibitisho wa cryptographic (kubadilisha vitalu vya zamani itahitaji viwango visivyoonekana vya nguvu ya kompyuta). Pia, blockchain Bitcoin ni imara sana na haraka kurekebisha kama majibu ya shambulio. Jambo jingine la chini la blockchain ni kwamba mara moja data imeongezwa kwenye blockchain ni vigumu sana kuibadilisha. Wakati utulivu ni moja ya faida blockchain, si daima nzuri. Kubadilisha data au nambari ya blockchain ni kawaida sana na mara nyingi inahitaji hard fork, ambapo mnyororo mmoja ni kutelekezwa na mpya ni kuchukuliwa. Blockchain hutumia ufunguo wa umma (au asymmetric) cryptography kutoa watumiaji umiliki juu ya vitengo vyao cryptocurrency (au data nyingine yoyote blockchain). Kila anwani ya blockchain ina ufunguo binafsi unaolingana. Wakati anwani inaweza kushirikiwa, ufunguo binafsi inapaswa kuhifadhiwa siri. Watumiaji wanahitaji ufunguo wao wa kibinafsi kupata fedha zao, ikimaanisha kwamba wao kutenda kama benki yao wenyewe. Ikiwa mtumiaji anapoteza ufunguo wake wa kibinafsi, pesa zinapotea kwa ufanisi, na hakuna kitu wanaweza kufanya juu yake. Blockchains, hasa wale kutumia Uthibitisho wa Kazi, ni inefficient sana. Kwa kuwa uchimbaji wa madini ni ushindani mkubwa na kuna mshindi mmoja tu kila dakika kumi, kazi ya wachimbaji wengine wote inapotea bure. Kama wachimbaji wa madini wanajaribu kuongeza nguvu zao za hesabu, wana nafasi kubwa ya kupata hash halali ya block, rasilimali zinazotumiwa na mtandao wa Bitcoin zimekuwa zikiongezeka sana katika miaka michache iliyopita, na kwa sasa hutumia nishati zaidi kuliko nchi nyingi kama vile Denmark, Ireland na Nigeria. Blockchain ledgers inaweza kukua kubwa sana kwa muda. Bitcoin blockchain inahitaji karibu 200 GB ya kuhifadhi. Ukuaji wa sasa katika ukubwa wa blockchain inaonekana kuwa outstripping ukuaji katika diski ngumu na mtandao hatari ya kupoteza nodes kama ledger inakuwa kubwa sana kwa watu binafsi kupakua na kuhifadhi. Licha ya hasara zake, teknolojia ya blockchain ina faida za kipekee, na ni dhahiri hapa kukaa. Bado tuna njia ndefu ya kupitishwa kwa kawaida, lakini viwanda vingi vinashughulikia faida na hasara za mifumo ya blockchain. Katika miaka ijayo, biashara na serikali zitakuwa na uzoefu wa majaribio ya matumizi mapya ili kujua ni wapi teknolojia ya blockchain inaongeza thamani zaidi.