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Browsing by Subject "blockchain"

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  • Lohkoketjut julkishallinnossa 
    Kalinen, Riku (2022)
    In this thesis, we cover blockchain applications in public administration. First we cover components related to blockchain technology. We cover especially issues related to management of digital evidence, electronic voting, and health data. In the beginning we cover hash functions and the general structure of the blockchain. Then we cover the cryptocurrency Bitcoin as an example of the blockchain technology. The management of the digital evidence is covered by evaluating three published studies. Likewise, the applications related to voting are evaluated in the light of three publications. Lastly, the management of health data is covered by evaluating three publications. For each of the three areas, we present an estimation of the applicability of the blockchain technology, in the form presented in the evaluated publications. Additionally, we cover a few other potential blockchain application areas. Finally, we present the general evaluation of blockchain applicability to the public administration and the conclusion.
  • On Self-Sovereign Identity : Verifiable Credentials and Presentations with OpenID Connect 
    Pärni, Miika (2023)
    Self-Sovereign Identity is a new concept of managaging digital identities in the digital services. The purpose of the Self-Sovereign Identity is to place the user in the center and move towards decentralized model of identity management. Verifiable Credentials, Verifiable Presentations, Identity Wallets and Decentralized Identifiers are part of the Self-Sovereign Identity model. They have also been recently included in the OpenID Connect specifications to be used with the widely used authentication layer built on OAuth 2.0. The OpenID Connect authentication can now be leveraged with the Decetralized Identifiers (DIDs) and the public keys contained in DID Documents. This work assessed the feasibility of integrating the Verifiable Credentials, Verifiable Presentations and Decentralized Identifiers with OpenID Connect in the context of two use cases. The first use case is to integrate the Verifiable Credentials and Presentations into an OpenID Connect server and utilise Single Sign-On in federated environment. The second use case is to ignore the OpenID Provider and enable the Relying Party to authenticate directly with the Identity Wallet. Custom software components, the Relying Party, the Identity Wallet and the Verifiable Credential Issuer were built to support the assessments. Two new authorization flows were designed for the two use cases. The Federated Verifiable Presentation Flow describes the protocol of Relying Party authenticating with OpenID Provider which receives the user information from the Wallet. The flow does not require any changes for any Relying Party using the same OpenID Provider to authenticate and utilise Single Sign-On. The Verifiable Presentation Flow enables the Relying Party to authenticate directly with the Wallet. However, this flow requires multiple changes to Relying Party and benefits of federated environment are not available, e.g., the Single Sign-On. Both of the flows are useful for their own specific use cases. The new flows are utilising the new segments of the Self-Sovereign Identity and are promising steps towards self-sovereignty.
  • Zero-knowledge proofs in blockchain applications 
    Tani, Antti (2020)
    The release of Bitcoin marked the birth of blockchain applications. Due, among other things, to the need for public verifiability, blockchain information is often transparent, which in many cases leads to insufficient privacy. Various methods have been developed to obfuscate the blockchain data, which should at the same time maintain public verifiability. A promising cryptographic approach is zero-knowledge proof that enables a statement to be proved without revealing any other information than the validity of the statement. Zero-knowledge proofs are examined in detail, first focusing on their general properties. With blockchains, the key features for zero-knowledge proof schemes are non-interactivity and succinctness, and schemes that fulfill these requirements are often called as zk-SNARKs. In a limited use, where succinctness is not critical, Fiat-Shamir transform has also been useful. We study the use of zero-knowledge proofs in blockchain applications Zcash, Ethereum and Monero, with a particular focus on privacy and feasibility.

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