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Review
. 2019 Aug 31;21(8):e13592.
doi: 10.2196/13592.

A Blockchain Framework for Patient-Centered Health Records and Exchange (HealthChain): Evaluation and Proof-of-Concept Study

Affiliations
Review

A Blockchain Framework for Patient-Centered Health Records and Exchange (HealthChain): Evaluation and Proof-of-Concept Study

Ray Hales Hylock et al. J Med Internet Res. .

Abstract

Background: Blockchain has the potential to disrupt the current modes of patient data access, accumulation, contribution, exchange, and control. Using interoperability standards, smart contracts, and cryptographic identities, patients can securely exchange data with providers and regulate access. The resulting comprehensive, longitudinal medical records can significantly improve the cost and quality of patient care for individuals and populations alike.

Objective: This work presents HealthChain, a novel patient-centered blockchain framework. The intent is to bolster patient engagement, data curation, and regulated dissemination of accumulated information in a secure, interoperable environment. A mixed-block blockchain is proposed to support immutable logging and redactable patient blocks. Patient data are generated and exchanged through Health Level-7 Fast Healthcare Interoperability Resources, allowing seamless transfer with compliant systems. In addition, patients receive cryptographic identities in the form of public and private key pairs. Public keys are stored in the blockchain and are suitable for securing and verifying transactions. Furthermore, the envisaged system uses proxy re-encryption (PRE) to share information through revocable, smart contracts, ensuring the preservation of privacy and confidentiality. Finally, several PRE improvements are offered to enhance performance and security.

Methods: The framework was formulated to address key barriers to blockchain adoption in health care, namely, information security, interoperability, data integrity, identity validation, and scalability. It supports 16 configurations through the manipulation of 4 modes. An open-source, proof-of-concept tool was developed to evaluate the performance of the novel patient block components and system configurations. To demonstrate the utility of the proposed framework and evaluate resource consumption, extensive testing was performed on each of the 16 configurations over a variety of scenarios involving a variable number of existing and imported records.

Results: The results indicate several clear high-performing, low-bandwidth configurations, although they are not the strongest cryptographically. Of the strongest models, one's anticipated cumulative record size is shown to influence the selection. Although the most efficient algorithm is ultimately user specific, Advanced Encryption Standard-encrypted data with static keys, incremental server storage, and no additional server-side encryption are the fastest and least bandwidth intensive, whereas proxy re-encrypted data with dynamic keys, incremental server storage, and additional server-side encryption are the best performing of the strongest configurations.

Conclusions: Blockchain is a potent and viable technology for patient-centered access to and exchange of health information. By integrating a structured, interoperable design with patient-accumulated and generated data shared through smart contracts into a universally accessible blockchain, HealthChain presents patients and providers with access to consistent and comprehensive medical records. Challenges addressed include data security, interoperability, block storage, and patient-administered data access, with several configurations emerging for further consideration regarding speed and security.

Keywords: HL7 FHIR; blockchain; chameleon hashing; digital health; electronic health records; health information exchange; health information management; medical records; patient-centered health; proxy re-encryption; redactable blockchain; smart contracts.

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Conflict of interest statement

Conflicts of Interest: None declared.

Figures

Figure 1
Figure 1
Block schematic with sample financial data and hashes.
Figure 2
Figure 2
Blockchain diagram with several blocks, including the foundational genesis block, and noted hash connections.
Figure 3
Figure 3
Proxy re-encryption process overview.
Figure 4
Figure 4
Mixed-block blockchain adaptation of Figure 2.
Figure 5
Figure 5
Patient account (ie, block) establishment, redaction, and logging processes in HealthChain.
Figure 6
Figure 6
Initial and subsequent patient data entry in a traditional blockchain.
Figure 7
Figure 7
Information retrieval in an immutable blockchain versus HealthChain.
Figure 8
Figure 8
Smart contract initiation using standard proxy re-encryption.
Figure 9
Figure 9
Smart contract execution using standard proxy re-encryption. FHIR: Fast Healthcare Interoperability Resources.
Figure 10
Figure 10
Smart contract initiation using 2-party proxy re-encryption decryption.
Figure 11
Figure 11
Smart contract execution using 2-party proxy re-encryption decryption. FHIR: Fast Healthcare Interoperability Resources; PRE: proxy re-encryption.
Figure 12
Figure 12
Transmission size in kilobytes and bytes per record by the number of records inserted. ADF: AES-encrypted data, dynamic keys, full block storage; ADI: AES-encrypted data, dynamic keys, incremental storage; AES: Advanced Encryption Standard; ASF: AES-encrypted data, static keys, full block storage; ASI: AES-encrypted data, static keys, incremental storage; PDF: PRE-encrypted data, dynamic keys, full block storage; PDI: PRE-encrypted data, dynamic keys, incremental storage; PRE: proxy re-encryption; PSF: PRE-encrypted data, static keys, full block storage; PSI: PRE-encrypted data, static keys, incremental storage.
Figure 13
Figure 13
Transmission size in kilobytes per record added given an existing record set. ADF: AES-encrypted data, dynamic keys, full block storage; ADI: AES-encrypted data, dynamic keys, incremental storage; AES: Advanced Encryption Standard; ASF: AES-encrypted data, static keys, full block storage; ASI: AES-encrypted data, static keys, incremental storage; PDF: PRE-encrypted data, dynamic keys, full block storage; PDI: PRE-encrypted data, dynamic keys, incremental storage; PRE: proxy re-encryption; PSF: PRE-encrypted data, static keys, full block storage; PSI: PRE-encrypted data, static keys, incremental storage.
Figure 14
Figure 14
Client-to-server network latency in seconds per inserted record (ie, insertion) and seconds per record added given an existing record set (ie, scaling) — includes connection establishment, termination, and transmission time. ADF: AES-encrypted data, dynamic keys, full block storage; ADI: AES-encrypted data, dynamic keys, incremental storage; AES: Advanced Encryption Standard; ASF: AES-encrypted data, static keys, full block storage; ASI: AES-encrypted data, static keys, incremental storage; PDF: PRE-encrypted data, dynamic keys, full block storage; PDI: PRE-encrypted data, dynamic keys, incremental storage; PRE: proxy re-encryption; PSF: PRE-encrypted data, static keys, full block storage; PSI: PRE-encrypted data, static keys, incremental storage.
Figure 15
Figure 15
Client-to-server network latency (transmission only) measured in megabits per second and milliseconds per fragment by the number of records inserted. ADF: AES-encrypted data, dynamic keys, full block storage; ADI: AES-encrypted data, dynamic keys, incremental storage; AES: Advanced Encryption Standard; ASF: AES-encrypted data, static keys, full block storage; ASI: AES-encrypted data, static keys, incremental storage; PDF: PRE-encrypted data, dynamic keys, full block storage; PDI: PRE-encrypted data, dynamic keys, incremental storage; PRE: proxy re-encryption; PSF: PRE-encrypted data, static keys, full block storage; PSI: PRE-encrypted data, static keys, incremental storage.
Figure 16
Figure 16
Server-to-client network latency (transmission only) measured in milliseconds and megabits per second by the number of records transmitted to the client. AES: Advanced Encryption Standard; AF: AES-encrypted data, full block storage; AI: AES-encrypted data, incremental block storage; PF: PRE-encrypted data, full block storage; PI: PRE-encrypted data, incremental storage; PRE: proxy re-encryption.
Figure 17
Figure 17
Client processing time in seconds and milliseconds per record by the number of records inserted. ADF: AES-encrypted data, dynamic keys, full block storage; ADI: AES-encrypted data, dynamic keys, incremental storage; AES: Advanced Encryption Standard; ASF: AES-encrypted data, static keys, full block storage; ASI: AES-encrypted data, static keys, incremental storage; PDF: PRE-encrypted data, dynamic keys, full block storage; PDI: PRE-encrypted data, dynamic keys, incremental storage; PRE: proxy re-encryption; PSF: PRE-encrypted data, static keys, full block storage; PSI: PRE-encrypted data, static keys, incremental storage.
Figure 18
Figure 18
Client processing time in milliseconds per record added given an existing record set. ADF: AES-encrypted data, dynamic keys, full block storage; ADI: AES-encrypted data, dynamic keys, incremental storage; AES: Advanced Encryption Standard; ASF: AES-encrypted data, static keys, full block storage; ASI: AES-encrypted data, static keys, incremental storage; PDF: PRE-encrypted data, dynamic keys, full block storage; PDI: PRE-encrypted data, dynamic keys, incremental storage; PRE: proxy re-encryption; PSF: PRE-encrypted data, static keys, full block storage; PSI: PRE-encrypted data, static keys, incremental storage.
Figure 19
Figure 19
Server processing time in seconds and milliseconds per record by the number of records inserted. ADFN: AES-encrypted data, dynamic keys, full block storage, no server-side encryption; ADFY: AES-encrypted data, dynamic keys, full block storage, server-side encryption; ADIN: AES-encrypted data, dynamic keys, incremental storage, no server-side encryption; ADIY: AES-encrypted data, dynamic keys, incremental storage, server-side encryption; AES: Advanced Encryption Standard; ASFN: AES-encrypted data, static keys, full block storage, no server-side encryption; ASFY: AES-encrypted data, static keys, full block storage, server-side encryption; ASIN: AES-encrypted data, static keys, incremental storage, no server-side encryption; ASIY: AES-encrypted data, static keys, incremental storage, server-side encryption; PDFN: PRE-encrypted data, dynamic keys, full block storage, no server-side encryption; PDFY: PRE-encrypted data, dynamic keys, full block storage, server-side encryption; PDIN: PRE-encrypted data, dynamic keys, incremental storage, no server-side encryption; PDIY: PRE-encrypted data, dynamic keys, incremental storage, server-side encryption; PRE: proxy re-encryption; PSFN: PRE-encrypted data, static keys, full block storage, no server-side encryption; PSFY: PRE-encrypted data, static keys, full block storage, server-side encryption; PSIN: PRE-encrypted data, static keys, incremental storage, no server-side encryption; PSIY: PRE-encrypted data, static keys, incremental storage, server-side encryption.
Figure 20
Figure 20
Server processing time in milliseconds per record added given an existing record set. ADFN: AES-encrypted data, dynamic keys, full block storage, no server-side encryption; ADFY: AES-encrypted data, dynamic keys, full block storage, server-side encryption; ADIN: AES-encrypted data, dynamic keys, incremental storage, no server-side encryption; ADIY: AES-encrypted data, dynamic keys, incremental storage, server-side encryption; AES: Advanced Encryption Standard; ASFN: AES-encrypted data, static keys, full block storage, no server-side encryption; ASFY: AES-encrypted data, static keys, full block storage, server-side encryption; ASIN: AES-encrypted data, static keys, incremental storage, no server-side encryption; ASIY: AES-encrypted data, static keys, incremental storage, server-side encryption; PDFN: PRE-encrypted data, dynamic keys, full block storage, no server-side encryption; PDFY: PRE-encrypted data, dynamic keys, full block storage, server-side encryption; PDIN: PRE-encrypted data, dynamic keys, incremental storage, no server-side encryption; PDIY: PRE-encrypted data, dynamic keys, incremental storage, server-side encryption; PRE: proxy re-encryption; PSFN: PRE-encrypted data, static keys, full block storage, no server-side encryption; PSFY: PRE-encrypted data, static keys, full block storage, server-side encryption; PSIN: PRE-encrypted data, static keys, incremental storage, no server-side encryption; PSIY: PRE-encrypted data, static keys, incremental storage, server-side encryption.
Figure 21
Figure 21
Smart contract execution time in seconds and milliseconds per record by the number of records processed. AES: Advanced Encryption Standard; AFY: AES-encrypted data, full block storage, server-side encryption; AFN: AES-encrypted data, full block storage, no server-side encryption; AIN: AES-encrypted data, incremental block storage, no server-side encryption; AIY: AES-encrypted data, incremental storage, server-side encryption; PFN: PRE-encrypted data, full block storage, no server-side encryption; PFY: PRE-encrypted data, full block storage, server-side encryption; PIN: PRE-encrypted data, incremental block storage, no server-side encryption; PIY: PRE-encrypted data, incremental storage, server-side encryption; PRE: proxy re-encryption.
Figure 22
Figure 22
Relative comparison of client and server processing time in milliseconds and transmission size in kilobytes per record by insertion and scaling. ADFN: AES-encrypted data, dynamic keys, full block storage, no server-side encryption; ADFY: AES-encrypted data, dynamic keys, full block storage, server-side encryption; ADIN: AES-encrypted data, dynamic keys, incremental storage, no server-side encryption; ADIY: AES-encrypted data, dynamic keys, incremental storage, server-side encryption; AES: Advanced Encryption Standard; ASFN: AES-encrypted data, static keys, full block storage, no server-side encryption; ASFY: AES-encrypted data, static keys, full block storage, server-side encryption; ASIN: AES-encrypted data, static keys, incremental storage, no server-side encryption; ASIY: AES-encrypted data, static keys, incremental storage, server-side encryption; PDFN: PRE-encrypted data, dynamic keys, full block storage, no server-side encryption; PDFY: PRE-encrypted data, dynamic keys, full block storage, server-side encryption; PDIN: PRE-encrypted data, dynamic keys, incremental storage, no server-side encryption; PDIY: PRE-encrypted data, dynamic keys, incremental storage, server-side encryption; PRE: proxy re-encryption; PSFN: PRE-encrypted data, static keys, full block storage, no server-side encryption; PSFY: PRE-encrypted data, static keys, full block storage, server-side encryption; PSIN: PRE-encrypted data, static keys, incremental storage, no server-side encryption; PSIY: PRE-encrypted data, static keys, incremental storage, server-side encryption.

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