In the previous two parts, we delved into Blockchain technology, its characteristics, and functionalities. In this final section, we will explore methods for enhancing privacy and security. Nonetheless, despite its benefits, Blockchain transactions are not anonymous as the public can verify addresses, enabling them to trace a user\u2019s pseudonymous transactions.<\/p>\n\n\n\n
When a user\u2019s actual identity is connected to a transaction address, it exposes all of their transactions to potential risk. To counteract this, developers have devised merge or flipper services, which randomize a user\u2019s coins by merging them with coins from other users. This method helps to safeguard user anonymity by preventing the tracing of their transactions.<\/p>\n\n\n\n
B\u00e1r a kever\u00e9s elrejti az \u00e9rm\u00e9k tulajdonjog\u00e1t a k\u00fcls\u0151 megfigyel\u0151k el\u0151l, a kever\u00e9si szolg\u00e1ltat\u00e1sok nem ny\u00fajtanak v\u00e9delmet az \u00e9rm\u00e9k ellop\u00e1sa ellen.<\/p>\n\n\n
Mixcoin<\/strong> volt az els\u0151 technika a passz\u00edv kibert\u00e1mad\u00e1sok elleni v\u00e9dekez\u00e9sre, amely lehet\u0151v\u00e9 tette a kriptovalut\u00e1k anonim fizet\u00e9s\u00e9t. Kiterjesztette az anonimit\u00e1si halmazt az\u00e1ltal, hogy lehet\u0151v\u00e9 tette az \u00f6sszes felhaszn\u00e1l\u00f3 sz\u00e1m\u00e1ra, hogy egyszerre keverje az \u00e9rm\u00e9it. A Mixcoin a hagyom\u00e1nyos kever\u00e9si kommunik\u00e1ci\u00f3hoz hasonl\u00f3 anonimit\u00e1st biztos\u00edt az akt\u00edv kibert\u00e1mad\u00e1sok elleni k\u00fczdelemhez.<\/p>\n\n\n\n A lop\u00e1s \u00e9szlel\u00e9s\u00e9re a Mixcoin egy elsz\u00e1moltathat\u00f3s\u00e1gi mechanizmust haszn\u00e1l, amely \u00f6szt\u00f6nz\u0151ket igaz\u00edt, megmutatva, hogy a felhaszn\u00e1l\u00f3k \u00e9sszer\u0171en haszn\u00e1lj\u00e1k a Mixcoin-t an\u00e9lk\u00fcl, hogy kriptovalut\u00e1t lopn\u00e1nak. <\/p>\n\n\n\n M\u00e1sr\u00e9szt, CoinJoin<\/strong> a m\u00e1sodik kever\u00e9si szolg\u00e1ltat\u00e1s az anonim kriptovaluta tranzakci\u00f3khoz. A k\u00f6z\u00f6s fizet\u00e9s \u00f6tlet\u00e9re t\u00e1maszkodik, ahol egy felhaszn\u00e1l\u00f3 tal\u00e1l egy m\u00e1sik felhaszn\u00e1l\u00f3t, aki szint\u00e9n fizetni szeretne, \u00e9s k\u00f6z\u00f6s fizet\u00e9st hajtanak v\u00e9gre egy tranzakci\u00f3ban.<\/p>\n\n\n\n A k\u00f6z\u00f6s fizet\u00e9si m\u00f3dszer haszn\u00e1lata jelent\u0151sen cs\u00f6kkenti az es\u00e9ly\u00e9t annak, hogy egy tranzakci\u00f3ban \u00f6sszekapcsolj\u00e1k a bemeneteket \u00e9s kimeneteket, megnehez\u00edtve a p\u00e9nz pontos \u00e1raml\u00e1s\u00e1nak nyomon k\u00f6vet\u00e9s\u00e9t egy adott felhaszn\u00e1l\u00f3 sz\u00e1m\u00e1ra. A CoinJoin haszn\u00e1lat\u00e1hoz a felhaszn\u00e1l\u00f3knak ki kell cser\u00e9lni\u00fck azokat a tranzakci\u00f3kat, amelyeket k\u00f6z\u00f6s fizet\u00e9sbe k\u00edv\u00e1nnak egyes\u00edteni. <\/p>\n\n\n\n Mindazon\u00e1ltal az ilyen funkcionalit\u00e1st biztos\u00edt\u00f3 kever\u00e9si szolg\u00e1ltat\u00e1sok els\u0151 gener\u00e1ci\u00f3ja k\u00f6zpontos\u00edtott szerverekre t\u00e1maszkodott, ami adatv\u00e9delmi kock\u00e1zatot jelentett egyetlen hibapont jelenl\u00e9te miatt. <\/p>\n\n\n\n Ezek a szolg\u00e1ltat\u00e1sok meg\u0151rzik a tranzakci\u00f3k nyilv\u00e1ntart\u00e1s\u00e1t, \u00e9s dokument\u00e1lj\u00e1k az \u00f6sszes k\u00f6z\u00f6s fizet\u00e9si r\u00e9sztvev\u0151t, megk\u00f6vetelve a felhaszn\u00e1l\u00f3kt\u00f3l, hogy b\u00edzzanak a szolg\u00e1ltat\u00f3ban, hogy nem vesz r\u00e9szt lop\u00e1sban, vagy nem engedi m\u00e1soknak, hogy ellopj\u00e1k kriptovalut\u00e1ikat.<\/p>\n\n\n A fejleszt\u0151k l\u00e9trehoztak digit\u00e1lis al\u00e1\u00edr\u00e1si technol\u00f3giai v\u00e1ltozatokat, amelyek anonimit\u00e1st biztos\u00edthatnak az al\u00e1\u00edr\u00f3nak, ezeket anonim al\u00e1\u00edr\u00e1soknak nevezik. K\u00e9t p\u00e9lda a csoportos al\u00e1\u00edr\u00e1s \u00e9s a gy\u0171r\u0171s al\u00e1\u00edr\u00e1s.<\/p>\n\n\n\n Group signing enables a group member to sign a message anonymously using their personal secret key. The group\u2019s public key verifies and authenticates the group signature, revealing only the signer\u2019s group membership.<\/p>\n\n\n\n In the Blockchain system, an authorized entity is required to create and manage groups for group signing. Ring signatures prevent disclosing the signer\u2019s identity during a dispute, and any user can form a \u2018ring\u2019 without additional configuration. The term \u201cring signature\u201d comes from the signature algorithm that uses a ring-shaped structure.<\/p>\n\n\n A homomorf kriptogr\u00e1fia egy er\u0151teljes titkos\u00edt\u00e1st alkalmaz, amely lehet\u0151v\u00e9 teszi a k\u00f6zvetlen sz\u00e1m\u00edt\u00e1sokat a titkos\u00edtott sz\u00f6vegen. Amikor a sz\u00e1m\u00edtott eredm\u00e9nyeket visszafejtik, a titkos\u00edtott adatokon v\u00e9grehajtott m\u0171veletek azonos sima sz\u00f6veges eredm\u00e9nyeket hoznak l\u00e9tre. A r\u00e9szleges \u00e9s teljesen homomorf rendszerek minim\u00e1lis m\u00f3dos\u00edt\u00e1sokkal t\u00e1rolhatj\u00e1k az adatokat a blokkl\u00e1ncon, biztos\u00edtva, hogy a nyilv\u00e1nos blokkl\u00e1ncokkal kapcsolatos adatv\u00e9delmi agg\u00e1lyok enyh\u00fcljenek. <\/p>\n\n\n\n Ez a technika adatv\u00e9delmi v\u00e9delmet ny\u00fajt, \u00e9s lehet\u0151v\u00e9 teszi a titkos\u00edtott inform\u00e1ci\u00f3k k\u00f6nny\u0171 el\u00e9r\u00e9s\u00e9t a munkav\u00e1llal\u00f3i k\u00f6lts\u00e9gek kezel\u00e9s\u00e9re, k\u00f6nyvvizsg\u00e1latra \u00e9s m\u00e1s c\u00e9lokra.<\/p>\n\n\n Attribute-Based Encryption is a cryptographic method that defines and governs ciphertext with a user\u2019s secret key attributes. Decryption is only possible if the attributes match the ciphertext attributes. ABE is important for collusion resistance to prevent cyber attackers from accessing other data. However, ABE is underutilized due to a lack of understanding of its basics and efficient implementation. Currently, no real-time operations have implemented ABE on a blockchain.<\/p>\n\n\n Secure Multi-Party Computing is a multi-party protocol that jointly performs computations on private data inputs without violating input privacy. A cyber attacker learns nothing about the input from an authentic party but from the exit. The success of using MPC in distributed voting, private bidding, and private information retrieval has made it a popular solution to many real-world problems. The first large-scale deployment of MPC was in 2008 for an absolute auction issue in Denmark. Blockchain systems have utilized MPC in recent years to safeguard users\u2019 privacy.<\/p>\n\n\n A nem-interakt\u00edv z\u00e9r\u00f3-tud\u00e1s bizony\u00edt\u00e9k egy kriptogr\u00e1fiai technol\u00f3gia, amely er\u0151teljes adatv\u00e9delmi tulajdons\u00e1gokat k\u00edn\u00e1l. A f\u0151 koncepci\u00f3 egy form\u00e1lis teszt l\u00e9trehoz\u00e1sa, amely meger\u0151s\u00edti, hogy egy program, amelyet csak a felhaszn\u00e1l\u00f3 \u00e1ltal ismert bemenettel hajtanak v\u00e9gre, k\u00e9pes nyilv\u00e1nosan el\u00e9rhet\u0151 eredm\u00e9nyeket gener\u00e1lni an\u00e9lk\u00fcl, hogy tov\u00e1bbi inform\u00e1ci\u00f3kat k\u00f6z\u00f6lne.<\/p>\n\n\n\n M\u00e1s szavakkal, egy hiteles\u00edt\u0151 bizony\u00edthatja egy ellen\u0151rz\u0151nek, hogy egy \u00e1ll\u00edt\u00e1s helyes an\u00e9lk\u00fcl, hogy hasznos inform\u00e1ci\u00f3t szolg\u00e1ltatna. A blokkl\u00e1nc-alkalmaz\u00e1sok minden sz\u00e1mlaegyenleget titkos\u00edtott form\u00e1tumban t\u00e1rolnak a l\u00e1ncon. A z\u00e9r\u00f3-tud\u00e1s bizony\u00edt\u00e9kok haszn\u00e1lat\u00e1val egy felhaszn\u00e1l\u00f3 k\u00f6nnyen bizony\u00edthatja egy m\u00e1sik felhaszn\u00e1l\u00f3nak, hogy elegend\u0151 egyenlege van egy p\u00e9nz\u00e1tutal\u00e1shoz an\u00e9lk\u00fcl, hogy felfedn\u00e9 sz\u00e1mlaegyenleg\u00e9t.<\/p>\n\n\n Ez a technika teljesen elszigetelt k\u00f6rnyezetet biztos\u00edt az alkalmaz\u00e1s sz\u00e1m\u00e1ra, amely megakad\u00e1lyozza, hogy m\u00e1s szoftveralkalmaz\u00e1sok \u00e9s oper\u00e1ci\u00f3s rendszerek beavatkozzanak, \u00e9s megismerj\u00e9k az azon fut\u00f3 alkalmaz\u00e1s \u00e1llapot\u00e1t. Az Intel Guard eXtensions (SGX) szoftver egy reprezentat\u00edv TEE megval\u00f3s\u00edt\u00e1si technol\u00f3gia.<\/p>\n\n\n Game-based solutions for smart contract verification are recent developments that use an interactive \u201cverification game\u201d to decide if a computational task was successful or not. These solutions offer rewards to encourage players to verify computational tasks and find errors so that a smart contract can safely perform a task calculation with verifiable properties.<\/p>\n\n\n\n In each round of the \u201cverification game\u201d, the verifier recursively checks a smaller subset of the computation, significantly reducing the computational load on the nodes. This approach provides an efficient and effective method for verifying smart contracts.<\/p>\n\n\n We described Blockchain\u2019s security and privacy attributes and techniques used to achieve them in blockchain-based systems and applications, including consensus algorithms, shuffling, anonymous signatures, encryption, secure multi-party computing, and non-interactive zero-knowledge proof, and secure verification of smart contracts.<\/p>\n\n\n\n Although only a few Blockchain platforms can achieve the set security objectives, blockchain security, and privacy have gained significant interest from academic research and industry. Understanding Blockchain\u2019s security and privacy properties is crucial in enhancing trust and developing defense techniques and countermeasures. Developing lightweight cryptographic algorithms and practical security and privacy methods is vital for the future development of Blockchain and its applications.<\/p>","protected":false},"excerpt":{"rendered":"Anonim al\u00e1\u00edr\u00e1sok<\/strong><\/h2>\n\n\n
Homomorf titkos\u00edt\u00e1s (HE)<\/strong><\/h2>\n\n\n
Attrib\u00fatum-alap\u00fa titkos\u00edt\u00e1s (ABE)<\/strong><\/h2>\n\n\n
Biztons\u00e1gos t\u00f6bbp\u00e1rti sz\u00e1m\u00edt\u00e1s (MPC)<\/strong><\/h2>\n\n\n
Nem-interakt\u00edv z\u00e9r\u00f3-tud\u00e1s bizony\u00edt\u00e9k (NIZK)<\/strong><\/h2>\n\n\n
Megb\u00edzhat\u00f3 v\u00e9grehajt\u00e1si k\u00f6rnyezet (TEE) alap\u00fa okos szerz\u0151d\u00e9sek:<\/strong><\/h2>\n\n\n
J\u00e1t\u00e9k-alap\u00fa okos szerz\u0151d\u00e9sek<\/strong><\/h2>\n\n\n
K\u00f6vetkeztet\u00e9s<\/strong><\/h2>\n\n\n