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Security Services Using Blockchains: A State of the Art Survey

Tara Salman, Maede Zolanvari, Aiman Erbad, Raj Jain, Mohammed Samaka

arXiv:1810.08735v1cs.CR

TL;DR

Centralized security services face challenges in distributed applications, motivating blockchain-based alternatives. This paper surveys and compares blockchain approaches across key security services and identifies both their coverage and scalability constraints.

  • Problem

    Distributed applications need provenance to track data and resources, but increasing replication and exposure of ownership information make tracking complex and potentially privacy-invasive.

  • Method

    The paper conducts a comprehensive survey of blockchain-based approaches for authentication, confidentiality, privacy, provenance, and integrity assurance.

  • Results

    The survey reports that authentication and confidentiality can use public-key encryption and signatures, while privacy, provenance, and integrity assurance are addressed in separate blockchain-based approaches.

  • Takeaways & Limitations

    Blockchain security services cover multiple distributed-security needs, including access-rule monitoring, provenance tracking, and integrity verification.

  • Takeaways & Limitations

    Blockchain-based security approaches remain constrained by scalability and performance problems as users and network nodes increase.

Abstract

from arXiv · show

This article surveys blockchain-based approaches for several security services. These services include authentication, confidentiality, privacy, and access control list (ACL), data and resource provenance, and integrity assurance. All these services are critical for the current distributed applications, especially due to the large amount of data being processed over the networks and the use of cloud computing. Authentication ensures that the user is who he/she claims to be. Confidentiality guarantees that data cannot be read by unauthorized users. Privacy provides the users the ability to control who can access their data. Provenance allows an efficient tracking of the data and resources along with their ownership and utilization over the network. Integrity helps in verifying that the data has not been modified or altered. These services are currently managed by centralized controllers, for example, a certificate authority. Therefore, the services are prone to attacks on the centralized controller. On the other hand, blockchain is a secured and distributed ledger that can help resolve many of the problems with centralization. The objectives of this paper are to give insights on the use of security services for current applications, to highlight the state of the art techniques that are currently used to provide these services, to describe their challenges, and to discuss how the blockchain technology can resolve these challenges. Further, several blockchain-based approaches providing such security services are compared thoroughly. Challenges associated with using blockchain-based security services are also discussed to spur further research in this area.

I. INTRODUCTION … C. Paper Organization

The paper surveys blockchain-based security services as an alternative to centralized or inefficient approaches, covering their conventional techniques, challenges, and proposed blockchain solutions. It organizes the discussion around authentication, confidentiality, privacy, integrity, provenance, and related mechanisms and applications.

  • I. INTRODUCTION: Blockchain is a secured, shared, distributed ledger that records and tracks resources through peer-to-peer majority decisions without a centralized trusted authority.It supports resource exchange between parties and is described as secure against attackers compromising the centralized controller.
  • I. INTRODUCTION: Blockchain-based applications target network security services including authentication, confidentiality, privacy, integrity, and provenance, which centralized or inefficient distributed approaches do not adequately secure.The paper identifies security as a major challenge for current applications and presents blockchain as addressing traditional challenges.
  • I. INTRODUCTION: The survey examines current applications, conventional security techniques, their challenges, and blockchain-based approaches intended to resolve those challenges.It also highlights proposed approaches that provide the desired security services.
  • A. Related Work: Unlike prior surveys focused on IoT, healthcare, digital currencies, or general blockchain challenges, this paper comprehensively surveys blockchain technology for security services.The services may be offered by enterprises with or without global verification or presented as research work.
  • B. Security Services and Mechanisms: Security services are divided into authentication, data privacy, data integrity, data confidentiality, non-repudiation, and data provenance, using mechanisms such as encryption and digital signatures.Authentication includes data-origin and entity authentication, with mechanisms provided through public-key cryptography.
  • B. Security Services and Mechanisms: The paper combines authentication and confidentiality because both use public-key cryptography, while discussing privacy and integrity separately; blockchain already provides non-repudiation.This classification determines the structure of the blockchain-based security-services discussion.
  • C. Paper Organization: The paper organization progresses from blockchain architecture and platforms to authentication and encryption, privacy and ACLs, data provenance and integrity, challenges, and concluding observations.Sections II–VIII cover these topics in sequence, with Section VII addressing challenges and Section VIII summarizing the discussion.

II. BLOCKCHAIN BACKGROUND · A. Blockchain Architecture · B. Mining a Block in a Blockchain

Blockchain architecture combines a shared distributed database with a network of nodes, while mining creates and validates blocks for attachment to that database. The section introduces blockchain principles and compares mining approaches, including their selection mechanisms and limitations.

  • II. BLOCKCHAIN BACKGROUND: The background section introduces blockchain technology, explains block construction, discusses blockchain characteristics, and compares open-source implementations.
  • A. Blockchain Architecture: A blockchain combines a database with a network of nodes, maintaining records in a shared, distributed, fault-tolerant, append-only database.Blocks are accessible to users but cannot be deleted or altered, and each block includes its predecessor’s hash.
  • A. Blockchain Architecture: Blockchain interactions can occur without a trusted third party because users broadcast transactions and nodes verify them before block construction.The interactions are recorded in the blockchain database to provide security requirements.
  • A. Blockchain Architecture: Valid blocks are attached to the blockchain and cannot later be deleted or altered, while invalid blocks are dropped and signed transactions and blocks cannot be denied.
  • A. Blockchain Architecture: Blockchain technology has three generations supporting money transactions, assets, and smart contracts, respectively.The first generation was published by Satoshi Nakamoto in 2009 and implemented through Bitcoin for money transactions.
  • B. Mining a Block in a Blockchain: Mining creates blocks for database attachment, and some applications reward the miner who creates the first valid block.Mining also enables nodes to create blocks that other nodes validate.
  • B. Mining a Block in a Blockchain: Mining selection approaches include PoW, PoS, PoSpace, PoI, MoT, minimum block hash, and PBFT.PoW is used in Bitcoin and many other blockchain technologies; PoS instead selects a miner pseudo-randomly according to wealth or stake.
  • B. Mining a Block in a Blockchain: Proof of Work can be undermined when attackers compromise more than 50 percent of mining nodes and wastes high computational power on mathematical puzzles.

C. Key Properties of Blockchains … A. Public Key Cryptography and Its Services

The paper presents blockchain as a distributed, decentralized, cryptographically secure technology with non-repudiation guarantees, and explains how public key cryptography provides authentication and confidentiality through paired keys.

  • C. Key Properties of Blockchains: Blockchains combine distributed operation, decentralized consensus, a trustless system, cryptographic security, and non-repudiation guarantees.These properties address problems summarized in Table III.
  • D. Blockchain Open-Source Implementations: Selecting a blockchain implementation is challenging because many open-source implementations exist and differ across several aspects.The paper compares popular implementations in Table IV and uses their features when discussing blockchain-based security services.
  • E. Summary: Blockchain is a distributed, shared, append-only, permanent database whose key properties support distributed applications such as IoT, healthcare, and automated supply chains.The literature includes variations intended to address challenges introduced by the first generation of blockchain technology.
  • III. ENCRYPTION AND THE AUTHENTICATION SERVICES: Encryption and authentication are core network security services commonly provided through public key cryptography.Using these techniques requires infrastructure to create, revoke, manage, distribute, use, and store keys or generated information.
  • A. Public Key Cryptography and Its Services: Public key cryptography uses a distributed public key and a secret private key to perform complementary operations such as encryption/decryption or signing/validation.The technique, also called asymmetric cryptography, was introduced by Diffie and Hellman in 1975 and remains widely adopted.
  • A. Public Key Cryptography and Its Services: Entity authentication uses a signature/verification procedure in which a private-key signature is validated with the signer’s public key.Because the private key remains confidential, only the entity itself can sign the message.
  • A. Public Key Cryptography and Its Services: Confidentiality uses the receiver’s public key for encryption and the receiver’s private key for decryption, so only the receiver or private-key holder can understand the data.The passage states that this procedure guarantees confidentiality.

B. Services’ Importance for the Current Applications · C. Key Management by the Public Key Infrastructure (PKI) · D. Problems with the Traditional PKI Systems

Entity authentication and message confidentiality are critical to current network applications, while PKI manages the keys supporting public-key cryptography. Traditional CA- and WoT-based PKI approaches introduce centralization, trust-building, identity-retention, security, availability, cost, and efficiency challenges.

  • B. Services’ Importance for the Current Applications: Entity authentication and message confidentiality are critical services for nearly all current network applications.In smart healthcare, transmitted data must be secured to protect patient privacy, while doctors, hospitals, and pharmacies must be authenticated for data access.
  • B. Services’ Importance for the Current Applications: Public/private-key algorithms such as RSA, ElGamal, and elliptic curve cryptography require infrastructure to generate and manage keys.Certificate authorities, web of trust, and entity-based cryptosystems support creating, managing, using, storing, and distributing keys.
  • C. Key Management by the Public Key Infrastructure (PKI): PKI provides key management for public-key cryptography through centralized CA-based or decentralized WoT-based approaches.CA-based PKI is the most commonly used approach and is standardized in X.509.
  • C. Key Management by the Public Key Infrastructure (PKI): CA-issued certificates authenticate users by binding each user to a public key, whereas WoT keys are generated locally and trusted through verification by another trusted user.WoT was proposed in 1992 by Phil Zimmerman.
  • D. Problems with the Traditional PKI Systems: Both traditional PKI techniques face several challenges requiring further discussion.The subsequent challenges concern CA-based and WoT-based systems.
  • D. Problems with the Traditional PKI Systems: CA-based PKI has three major challenges: a trusted third party, a single-point-of-failure, and cost.Users must trust the CA to generate and manage keys, the system fails if the CA fails, and centralized key management can be expensive and inefficient at massive scale.
  • D. Problems with the Traditional PKI Systems: WoT-based PKI can create an entry barrier because new members must establish prior trust with existing trusted members.Users join the network only after being trusted by another trusted member.
  • D. Problems with the Traditional PKI Systems: Both CA- and WoT-based PKI can fail to retain identities, allowing impersonation of a registered user’s identity or public key.Proposed solutions are mostly log-based and may become highly complex when users are distributed worldwide.

E. Blockchain-Based PKI Concept

Blockchain-based PKI uses distributed, event-recording, and non-reproducibility properties to reduce reliance on centralized certificate authorities and their single points of failure. Surveyed approaches include CA monitoring, blockchain certificate storage, IoT key validation, and decentralized identity systems, but several retain centralization or lack complete implementation.

  • E. Blockchain-Based PKI Concept: Blockchain-based PKI distributes trust through miner majority voting, eliminating a centralized point of failure and the need for a single trusted third party.The survey identifies distribution, event recording, and non-reproducibility as properties supporting blockchain-based PKI and DNS.
  • Instant Karma PKI (IKP): IKP records certificate-authority behavior on the blockchain so network participants can track misbehavior and detect compromised or misbehaving CAs.However, retaining a CA preserves a single point of failure, while using several CAs increases cost.
  • Pemcor: Pemcor stores certificate hashes and revocations in authority-controlled blockchain databases, but remains theoretical and lacks complete implementation and evaluation.Its project targets identity proofing as an alternative to traditional knowledge-based verification.
  • Gan’s Approach: Gan’s IoT approach uses a private blockchain and manufacturer validators to store, validate, and distribute device public keys under a secured centralized CA.Its open-source NS3 implementation was evaluated for IoT and could also apply to sensor networks, healthcare, or micro-cloud platforms.
  • Common Limitations and Decentralized PKI: The first three approaches use blockchains mainly as distributed key databases and therefore do not exploit distributed consensus or non-repudiation; retaining a CA preserves centralization.A later decentralized PKI proposal introduced direct user control and ownership of data, though it omitted implementation details and enabled subsequent work.
  • Blockstack: Blockstack ID uses Namecoin transactions to bind user identities to public keys and serves as a blockchain-based PKI system for 55,000 users.The approach had not addressed public-key updates, lookups, revocations, or identity retention.

F. Identity-Based Cryptography (IBC)

Identity-based cryptography uses a node’s identity as its public key, simplifying public-key use through setup, extraction, encryption, and decryption phases. Hierarchical IBC extends this model with tree-structured identities and delegation for generating children’s secret keys.

  • Identity-Based Cryptography: IBC uses a node’s name or arbitrary identity string as its public key instead of a lengthy traditional public key.The approach comprises setup, extract, encrypt, and decrypt phases.
  • Identity-Based Cryptography: During setup, a private key generator creates a master secret key and public system parameters, then derives user secret keys from both and the user’s ID.The master secret remains private while system parameters are public.
  • Identity-Based Cryptography: IBC signatures use a node’s secret key for generation and its identity with public system parameters for verification.This mirrors the identity-based separation between private signing and public verification information.
  • Hierarchical IBC: Hierarchical IBC represents public keys as tree-based identities, such as Alice@X, and adds delegation to the four IBC phases.Delegation allows an entity to generate secret keys for its children.

G. Problems with the Current IBC-Based Approaches … IV. PRIVACY SERVICES

The surveyed IBC approaches remain centralized because PKGs generate private keys, whereas blockchain-based IBC distributes key management and public-parameter verification. The section then frames privacy as owner-controlled disclosure through access-control rules.

  • G. Problems with the Current IBC-Based Approaches: IBC and HIBC centralize private-key generation in the PKG, creating a single point of failure and requiring third-party trust.A compromised PKG compromises the entire system, leaving these approaches with the same limitation as traditional CA-based PKI.
  • H. Blockchain-Based IBC: Blockchain-based IBC uses a decentralized database to remove PKG centralization and allow users to generate their own master keys.Users with limited resources may delegate key generation to another party.
  • H. Blockchain-Based IBC: Blockchain-based IBC requires users to perform setup and extraction, then submit public parameters as transactions for node validation and later retrieval.The parameters support user authentication and encryption of confidential data.
  • H. Blockchain-Based IBC: Subscribers query the distributed blockchain for content-related public parameters instead of consulting a centralized PKG, while committed transactions provide nonrepudiable records.The scheme registers public parameters through new blockchain transactions before subscribers access corresponding data.
  • H. Blockchain-Based IBC: Initial implementations showed high complexity in public-key generation, restricting practicality and popularity for resource-limited ICN applications.The scheme can be applied to ICN and similar applications, but key-generation complexity remains a limitation.
  • I. Summary: Public-key cryptography supports authentication and confidentiality, while PKI provides infrastructure to generate, distribute, and manage public keys.These services are important for current applications including IoT and healthcare.
  • IV. PRIVACY SERVICES: Privacy lets data and resource owners control disclosure by defining access-control-list rules for information accessed through the network.The section examines privacy requirements, importance, traditional techniques, and challenges in providing privacy efficiently.

A. Data Privacy and ACL … BASED SOLUTIONS

The section frames privacy and ACLs as requirements for controlling sensitive data across its lifecycle, then surveys traditional limitations and blockchain-based approaches that decentralize ownership, authorization, and monitoring. The surveyed systems show feasibility but continue to face complexity, latency, scalability, implementation, and practicality challenges.

  • A. Data Privacy and ACL: Data privacy keeps personal and sensitive information confidential and under data-owner control, while ACLs specify who may access particular data and when.
  • B. Importance of Privacy in Current Applications: Privacy concerns span data collection, storage, use, destruction, deletion, motion, and rest, making privacy a major concern for application and network developers.
  • B. Importance of Privacy in Current Applications: Cloud, IoT, healthcare, smart-grid, and networking applications process massive data volumes, while shared infrastructure, personal or location information, and multiple-cloud interconnection intensify privacy requirements.
  • C. Traditional Techniques for Data Privacy: Traditional privacy techniques delegate ACL definitions to data owners and use encryption, with homomorphic encryption among the proposed techniques.
  • D. Problems with the Traditional Techniques: Traditional approaches remain challenged by efficiency, scalability, data ownership, and the lack of a systematic data-lifecycle framework covering acquisition, sharing, and deletion.
  • E. Blockchain-Based Data Privacy Techniques: Blockchain can provide decentralized end-to-end privacy, support data-ownership solutions, and dynamically change access rights, although cryptographic dependence preserves technical complexity.
  • BASED SOLUTIONS: Blockchain-based designs use smart contracts and permissioned networks to let owners define ACLs, publish encrypted policies and data, and restrict organizational processing to authorized access.
  • BASED SOLUTIONS: FairAccess was feasible for a specific IoT use-case, while DRAMS resisted several access-rights and log-compromise threats; surveyed implementations nevertheless retain practicality limits involving latency, cost, scalability, and missing real-time support.

F. Summary and Comparisons

The section summarizes blockchain-based data privacy approaches that preserve users’ control over data disclosures and prevent unauthorized access and processing. These approaches decentralize access-control management and monitoring through blockchain mechanisms.

  • Data privacy gives users control over data disclosures while preventing unauthorized access and processing.The paper identifies data privacy as a critical security aspect.
  • Blockchain-based privacy approaches define access-control lists through smart contracts or special management transactions.These mechanisms specify how access permissions are established without relying solely on centralized controllers.
  • Blockchain nodes can monitor access rules and violations, helping eliminate centralization in privacy management.The section also compares blockchain-based data privacy approaches in Table VIII.

COMPARISON … B. Importance of Provenance

The paper introduces provenance as a security service for tracking data and resource origins, operations, ownership, and access across distributed applications. It emphasizes provenance’s value for tractability, forensics, auditability, and detecting unauthorized activity, while noting complexity and privacy challenges.

  • COMPARISON: The comparison section situates provenance among the paper’s security services and frames blockchain as a potential solution to centralized provenance limitations.It compares traditional provenance techniques with blockchain-based architectures and approaches.
  • A. Data and Resource Provenance: Provenance tracks data and resource origins, associated operations, inputs, entities, systems, and processes that access or manipulate them.It can record data ownership and access in cloud environments with massively scaled and widely shared resources.
  • A. Data and Resource Provenance: Provenance provides resource tractability, forensic capabilities, and auditability for distributed applications.These capabilities help network administrators detect access violations and malicious operations.
  • A. Data and Resource Provenance: Maintaining provenance is challenging because distributed resources may be replicated across locations and follow different conditions or histories.The service also raises privacy-violation concerns alongside its complexity.
  • B. Importance of Provenance: In cloud, IoT, social-networking, and other distributed applications, owners need lifecycle visibility into data originality, manipulations, and accesses.IoT sensor data, for example, must reach consumers without unauthorized modification.
  • B. Importance of Provenance: Consumers also need provenance information to assess the accuracy and trustworthiness of data received from distributed systems.The paper presents provenance guarantees as crucial for these applications.

C. The Traditional Techniques … BLOCKCHAIN-BASED SOLUTIONS

Traditional cloud provenance relies on centralized logging and auditing, but distributed infrastructure, resource mobility, privacy concerns, complexity, and centralized controllers limit these techniques. Blockchain-based systems address provenance by recording immutable evidence and enabling applications such as cloud data tracking and supply-chain traceability, although centralized verification, scalability, and performance remain challenges.

  • C. The Traditional Techniques: Traditional cloud data-provenance techniques rely on centralized logging and auditing, including PASS, S2Logger, and SPROVE.PASS collects and maintains information about system-level operations.
  • D. Problems with the Traditional Techniques: Distributed cloud layers and mobile resources make logging inefficient and tracking complex, while centralized controllers and limited privacy further constrain traditional techniques.The passage identifies ineffectiveness, complexity, lack of privacy, and centralized controllers as key challenges.
  • E. Blockchain-Based Data Provenance: Blockchain can provide data provenance by recording evidence of data originality and operations in an immutable shared ledger.Blockchain-based provenance must still protect block integrity and confidentiality.
  • BLOCKCHAIN-BASED SOLUTIONS: ProvChain stores encrypted provenance records as blockchain transactions, but a centralized provenance auditor verifies operations and records off-chain.The system uses the blockchain database for integrity and non-repudiability guarantees without using blockchain consensus for verification.
  • BLOCKCHAIN-BASED SOLUTIONS: DataProv combines Ethereum smart contracts with an off-chain JavaScript module to provide provenance services for sensitive cloud information.It uses Document_Track and Vote contracts and was evaluated in drug-trial and wheat-production scenarios.
  • BLOCKCHAIN-BASED SOLUTIONS: DataProv demonstrated provenance guarantees with low cost and moderate overhead in real-life evaluations.The evaluation used drug trials and wheat production as specific use-cases.
  • BLOCKCHAIN-BASED SOLUTIONS: Smart-contract approaches can provide privacy and provenance for shared data, but blockchain complexity creates scalability and performance limitations.The accountability and provenance approach defines access rules in public blockchains and can support applications such as smart healthcare.
  • BLOCKCHAIN-BASED SOLUTIONS: Supply-chain systems such as Provenance assign digital identities to physical products for traceability and can be extended to audit cloud data and digital resources.Use-cases demonstrated tracking commercial products such as foods and goods, while other systems target counterfeit detection and fraud.

F. Summary and Comparisons · COMPARISON · VI. INTEGRITY ASSURANCE SERVICE

The survey emphasizes provenance for tracking data ownership, changes, originality, validity, and timing, while identifying inefficiencies and privacy limitations in traditional techniques. It also frames blockchain as useful for integrity verification but notes that blockchain-based provenance still requires further research.

  • F. Summary and Comparisons: Data provenance tracks ownership and changes to help assess data originality, validity, and timing in current applications.It is also important for auditing and detecting security violations.
  • F. Summary and Comparisons: Traditional data-provenance techniques are often inefficient, complex, centralized, and insufficiently protective of sensitive information.
  • F. Summary and Comparisons: DataProv’s communication complexity and ProvChain’s centralized provenance authority indicate that blockchain-based data provenance needs further research.Proper utilization of smart contracts could enhance these approaches.
  • COMPARISON: The comparison covers blockchain-based data-provenance approaches.
  • VI. INTEGRITY ASSURANCE SERVICE: Integrity assurance verifies that data has not been modified or altered when at rest or in motion.
  • VI. INTEGRITY ASSURANCE SERVICE: The integrity-assurance section discusses the service’s importance, traditional techniques, associated challenges, and blockchain-based integrity-verification platforms.

A. Integrity Assurance … E. Blockchain-Based Integrity Assurance

The section defines integrity assurance as protecting data correctness throughout its lifecycle, explains limitations of traditional cryptographic approaches, and surveys blockchain-based methods that provide tamper evidence and integrity verification. It highlights IoT, distributed storage, and cloud-oriented implementations alongside their practical limitations and adoption.

  • A. Integrity Assurance: Integrity assurance protects stored, accessed, generated, transmitted, and cloud-resident information from unauthorized alteration or corruption.It applies to information both in motion and at rest.
  • A. Integrity Assurance: End-to-end integrity assurance preserves information consistency, reliability, accuracy, and trustworthiness throughout its lifecycle.Integrity is identified as a basic component of the CIA triad and a required service for interconnection systems.
  • B. Integrity’s Importance for The Current Applications: Massive remote communications involving many actors, intermediate devices, and domains expose data and users to attacks including theft and alteration.In smart healthcare, altered patient or sensor information can have serious consequences.
  • C. Traditional Integrity Assurance Techniques: Traditional integrity assurance commonly uses public-key cryptography or keyless signature infrastructure to sign data and detect unauthorized changes through signature validation.These approaches sign data or resources so unauthorized modifications can be detected.
  • D. Problems with the Traditional Techniques: Traditional techniques can verify tampering but may not identify the intruder because alteration can occur during storage, processing, or communication.Identifying intruders could support malicious-behavior detection, access-control changes, and penalties.
  • E. Blockchain-Based Integrity Assurance: Blockchain architectures address traditional problems by signing transactions, verifying them through miners, preventing tampering after commitment, and providing evidence of data changes.Blockchain transactions can therefore submit data or assets while supporting integrity assurance and change tracking.
  • E. Blockchain-Based Integrity Assurance: Blockchain integrity approaches remain constrained by deployment and resource considerations, including limited blockchain use in a small-scale private IoT framework and adoption expectations in cloud services.Storj has been tested in real-case scenarios and used by some enterprises, while Ericsson provides an open-source SDK for immutable cloud-data evidence.
  • E. Blockchain-Based Integrity Assurance: Storj uses blockchain-stored data hashes to verify integrity in a peer-to-peer storage system, with data stored on-chain or off-chain alongside transaction metadata.The system is immutable by design and supports integrity-guaranteed distributed storage.

F. Summary … C. Communication Overhead

The paper summarizes blockchain-based integrity assurance and identifies practical challenges affecting blockchain security applications. These challenges include limited privacy, computational demands, and communication overhead, while provenance can help track data changes.

  • F. Summary: Blockchain can provide data integrity assurance through cryptographic signatures, verification techniques, and non-repudiation guarantees.The paper compares several blockchain-based integrity assurance approaches.
  • F. Summary: None of the proposed integrity approaches guarantees tracking intruders after data changes, but combining them with provenance can identify who last changed the data.Provenance enables tracking of the data and detection of the last changer.
  • VII. BLOCKCHAIN CHALLENGES: Blockchain’s potential benefits are constrained by challenges that limit its practicality for the security applications studied.The paper relates these challenges to the previously discussed security applications.
  • A. Privacy and Anonymity: Blockchain’s pseudo-user anonymity is weakened when transactions link identities to public keys, ACLs, or provenance data.This linkage can make users non-anonymous in ACL, key-management, and provenance approaches.
  • B. Computations and Mining Nodes: Security services require substantial encryption, decryption, and signature computations, while many applications use nodes with limited computational capabilities.Blockchain mining nodes additionally require high computational power.
  • C. Communication Overhead: Dynamic applications require frequent ACL and provenance updates, adding network-traffic and system-processing overhead because transactions and blocks must be broadcast.Frequent changes force nodes to send frequent update transactions across the peer-to-peer network.

D. Scalability … AND PROPOSED SOLUTIONS

The survey identifies scalability and time consumption as major challenges for blockchain-based security services, while describing local blockchain logs and broader blockchain mechanisms as proposed ways to address them. It concludes by synthesizing security services, traditional approaches, blockchain solutions, comparative approaches, and remaining challenges.

  • D. Scalability: Blockchain performance deteriorates as users and networking nodes increase, making scalability especially challenging for security applications serving thousands of users.System dynamicity worsens scaling because nodes must frequently send updates.
  • D. Scalability: Ethereum and Hyperledger promise scalability, but performance tests show that both platforms still suffer from scalability issues.The passage attributes this finding to performance tests reported in.
  • E. Time Consumption: Mining and consensus remain time-consuming, so proposed approaches make security decisions from local blockchain logs without requiring distributed consensus.Blockchain-based ACL mechanisms, for example, base access decisions on local blockchain copies.
  • F. Summary: The survey identifies privacy and scalability as the most difficult challenges among privacy and anonymity, computation and mining, communication overhead, scalability, and time consumption.These challenges arise from providing security services while meeting current application requirements.
  • I. CONCLUSIONS: The paper surveys blockchain use for entity authentication, confidentiality, privacy, provenance, and integrity assurance in distributed security services.It discusses public-key cryptography, encryption, signature schemes, and blockchain-based key management for authentication and confidentiality.
  • AND PROPOSED SOLUTIONS: The survey defines each security service, reviews traditional approaches and their challenges, explains blockchain-based resolutions, and compares different blockchain-based approaches.This summarizes the paper’s stated coverage and comparative analysis.
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