A PKI without TTP based on conditional trust in blockchain

Abstract

Many people have used public keys in various areas based on public key infrastructure (PKI). PKI provides a method to publicize public keys securely. However, existing PKI methods have a problem that they assume trusted third parties. Therefore, the existing PKIs cannot be used when users cannot trust certificate issuers. To solve this problem, we propose a new trust model and describe its implementation based on blockchain. Users can trust the certificate issued by full nodes even if they do not trust the full nodes themselves. We analyze the security of our model and show that its security can be achieved higher than existing models. This new model can be particularly useful in an environment where a third party cannot be easily trusted.