In order to back up your users' private keys, the e3kit method eThree.backupPrivateKey()
 requires a password in string format to properly secure it in Virgil services. However, password authentication might be optional or nonexistent in your app.
To still accomplish this, a password can be made out of three secret questions to be selected and answered by the user. For example:
In what city was your first job? New York.
How was your first pet called? Pluto.
What was your favorite food as a child? Pizza.
In this case, the selected questions and answers can be concatenated and normalized in lowercase to be used as a password for the backup:
"jobtown:newyork+firstpet:pluto+childfood:pizza"