# Latency Analysis of Blockchain-Based SSI Applications +
## 2 Related Works  
EBSI ([[https://ec.europa.eu/cefdigital/wiki/display/CEFDIGITAL/EBSI](https://ec.europa.eu/cefdigital/wiki/display/CEFDIGITAL/EBSI)]([https://ec.europa.eu/cefdigital/wiki/display/CEFDIGITAL/EBSI](https://ec.europa.eu/cefdigital/wiki/display/CEFDIGITAL/EBSI)), accessed on 26 September 2022) and BCD Diploma ([[https://www.bcd](https://www.bcd)]([https://www.bcd](https://www.bcd)) Diploma.com/en-GB, accessed on 26 September 2022) are examples of services built for providing Verifiable Credential (VC) supportive platforms utilizing Decentralized Identifiers (DIDs). The BC acts as the Trusted Third Party (TTP) where system entities save their data. However, the standard recommendation of W3C ([[https://www.w3.org/TR/vc-data-model/#introduction](https://www.w3.org/TR/vc-data-model/#introduction)]([https://www.w3.org/TR/vc-data-model/#introduction](https://www.w3.org/TR/vc-data-model/#introduction)), accessed on 26 September 2022) and the solutions following it did not consider the issuer accreditation issue, assuming any entity should be able to own a DID and issue any type of VCs. The BCD Diploma platform directly saves all issued VC hashes on the BC, which means that they can never be deleted, and it uses a PoW-based BC with a linear DL model. Additionally, an issuer accreditation service is not provided. Specifically, EBSI utilizes the general purpose Hyperledger Fabric ([[https://www.hyperledger.org/use/fabric](https://www.hyperledger.org/use/fabric)]([https://www.hyperledger.org/use/fabric](https://www.hyperledger.org/use/fabric)), accessed on 26 September 2022) which uses the Raft Consensus algorithm. In [16; 17], a BC-based data management system that could be used for the Global Legal Entity Identifier System (GLEIS) is proposed. Towards realizing this, the authors utilized Hyperledger Indy and their previously proposed GraphChain [18]. The implementation and utilization model of the proposed solution were presented, in which some challenges were faced, such as the limited message size of Indy. [PERSON] et al. [19] examined certain scenarios of personal data disclosure via credential exchanges between different identities and the risks of man-in-the-middle attacks in a BC-based identity system utilizing Hyperledger Indy. On the basis of the findings, the authors proposed enhancing Indy with a novel attribute sensitivity score model for SSI agents to ascertain the sensitivity of attributes shared in credential exchanges. Additionally, they proposed a method for mitigating man-in-the-middle attacks between peers SSIs. Finally, they proposed a novel quantitative model for determining a credential issuer's reputation based on the number of issued credentials in a window period, which is then utilized to calculate an overall confidence level score for the issuer. [PERSON] et al. [20] proposed an architecture for decoupling identities and trade activities on BC-enabled supply chains, namely TradeChain. The authors demonstrated the feasibility of TradeChain by implementing a proof of concept on Hyperledger Fabric and Indy. The limited latency evaluations provided in this study are within the ranges we obtained by our experiments. [PERSON] et al. [21] proposed that Indy and Aries agents can be implemented and utilized to realize a connected vehicle information network solution. The authors described several challenges they faced when utilizing those two projects, including the high latency and scalability limitations. However, the paper did not provide specific latency measures and settled for a description of the solution. A detailed and comprehensive study related to different BC platforms, including Indy and Aries, is presented in [22]. Here, well-documented tutorials and implementations can be found, as well as descriptive methods and algorithms for different consensus and block confirmation approaches. Additionally, architectural and low-level details have been differentiated between the studied BC platforms.