How to provide secure password based encryption with password reset option
In every of these options the essential step is to save it in secure place. Instead of implementing any of these options, just tell the user to keep the password in the same secure place that you have in mind for the 2nd key. All major risks will be the same as for keeping there the 2nd key, but this solution will cost you nothing - no implementation, no costs.
To answer your question precisely: What is the pro ...? I don't see any &quot;pro&quot;, because they are not more secure than keeping the original password at the same secure place. To &quot;cons&quot;: additional complexity to implement such process and to maintain it without getting any more security.
In case of option 3 additional complexity (also without additional security) comes from the fact that 2 of 2 keys are needed. This is effectively the same as &quot;simple&quot; splitting of the key into 2 parts without using any complex method.