Chotikakamthorn, Nopporn

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Chotikakamthorn, Nopporn
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Chotikakamthorn, N.
Chotikakamthornb, Nopporn
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nopporn.ch@kmitl.ac.th

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    Item type:Publication,
    Blockchain-based Learning Credential Revision and Revocation Method
    (2020-10-07)
    San, Aye Mi
    ;
    Chotikakamthorn, Nopporn
    ;
    Sathitwiriyawong, Chanboon
    Many blockchain-based learning credential systems have been proposed to reduce fraud and improve verification efficiency. In addition to a method for issuing and verifying credentials, a solution is needed to support the revision and revocation of an issued credential record. For the case of learning credentials, depending on how a revocation policy affects credential use that occurred before the revocation date, an additional mechanism may be needed for credential revision. Current digital learning credential methods offer only a revocation mechanism. So they do not fully meet such unique requirement in the education context. In this paper, a blockchain-based method for learning credential revision and revocation is proposed. It makes use of the revision and revocation addresses assigned to each batch of issuing credentials. To revise (revoke) one or more credentials, the proposed method stores the revision (revocation) list as a message in the OP_RETURN field of the revision (revocation) transaction, with the revision (revocation) address as one of its outputs. The concept of a local credential id has been introduced to allow a revision (revocation) list to be efficiently stored on a blockchain system. It is based entirely on a blockchain system and does not require any centralized authority. It is also applicable to most blockchain systems. A comparative study of the proposed method against existing credential revocation methods is also provided.
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    Item type:Publication,
    Blockchain-based Learning Credential Verification System with Recipient Privacy Control
    (2019-12-01)
    San, Aye Mi
    ;
    Chotikakamthorn, Nopporn
    ;
    Sathitwiriyawong, Chanboon
    Various forms of learning credentials play an important role in society. For example, a degree certificate is usually required to apply for many jobs. Currently, paper-based learning credentials such as diploma or degree certificates are still widely used. However, proof of such credentials' authenticity has become increasingly more difficult in recently years due to availability of low-cost desktop publishing tools. Recently, a blockchain-based digital certificate issuing and verification system has been proposed to address these problems. However, existing blockchain-based certification verification solutions have a few shortcomings in common. One of them is the lack of mechanism to control the amount of information and anonymity exposed during the verification process. This paper proposed a blockchain-based learning credential verification system, where a} {credential recipient can control the amount of credential-related information to be exposed during the verification process. The proposed solution makes use of a Merkle tree to encode causal relationship among pieces of information the credential is composed of. The abstract data model built on top of the binary Merkle tree has been proposed so that a recipient can choose to disclose part of the credential information, including the recipient profile. This means it is possible for credential verification to be performed anonymously. This can be achieved without increasing blockchain transaction cost and complexity. Example of use case scenarios that require such anonymous verification are described.
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    Item type:Publication,
    On-Chain Verifiable Credential with Applications in Education
    (2024-07-01)
    Chotikakamthorn, Nopporn
    ;
    Mi San, Aye
    ;
    Sathitwiriyawong, Chanboon
    A verifiable credential (VC) has been standardized and applied in vari-ous domains, including education. Due to its immutability, blockchain has been considered and used for credential issuance and verification. Most existing methods, however, are not compatible with the W3C VC stan-dard. In this paper, an on-chain VC issuance and verification method has been described. The method is based on the standard VC data model and applicable to any credential type. It decomposes a VC document into a VC template and the corresponding value array(s). This allows a VC to be issued on-chain in the Bitcoin BTC network, which has a limited data-embedding capacity. The proposed method reduces blockchain resource consumption due to the reusability of a VC template. In addition, it allows the use of a concise VC fingerprint format instead of a full VC for credential exchange. Two issuance modes, namely the full on-chain and partial on-chain, are proposed targeting different use cases. The proposed method has been applied for issuing and verifying two learning credential types. The method was evaluated on the Bitcoin Testnet to measure time and space complexities. With the reduced-size VC fingerprint, the proposed method can embed a VC on a traditional paper-based credential as a compact-sized QR code. The proposed method ofiered faster VC issuance and verification than an existing standard-based verifiable credential method.