> For each user, a pair of private-public keys were provided (https://msdn.microsoft.com/fr-fr/library/windows/desktop/aa3...). These are asymmetric cryptographic data that enable authentication on Blockchain. These were randomly attached in one-to-one correspondence to the user’s emails. We focused on Blockchain’s usage in the time-stamping and archiving logic. We did not let users create or use their own Blockchain authentication setup (i.e., if a user owned a Bitcoin account, the key and Bitcoin address were not allowed to be used). This restriction was related not to the Blockchain complexity but rather to maintain a simple and common email-focused authentication process. Other ways for authentication include the physical devices USB keys or cell phone fingerprints, but this would have been outside the focus of our protocol-related problematics.

So basically, we didn't want users to have to bother with this whole private key thing, so we'll hold on to those private keys for them. In other words, they have full control of whats written on the blockchain and users just trust them - which is the exact thing blockchains are trying to get rid of.

https://f1000research.com/articles/6-66/v5?source=post_page-...