Need to identify "verified" depositors

Can we allocate some brain-power to this? ... It's becoming increasingly necessary to be able to identify whether site-members are really depositors or not. One significant reason for doing this is so that some polls can be restricted to "verified" depositors only.

There is a conflict between the need to offer privacy to members and the need to get factual information from them. So, the optimum solution would be one that allowed us to verify beyond doubt that any particular site-member really is a depositor but without having to capture nor store any personal information about that depositor. Such a solution is almost certainly impossible, but philosophically speaking remains the objective.

Here are the two approaches I have designed to date:

1. Physical documentation linked to a code-word/password

All depositors post a letter with supporting evidence to a DAG representation. After confirming valid status, DAG allocate a unique password/code to those depositors. This password/code can identify the depositor and establish their identity. It would be used to limit access to "formal" polls, etc.

2. Formal declaration of status

All site-members are asked to complete an online form which formally asks them to confirm their status as depositors. As a result, their site membership profile is updated to reflect a "verified" status. This status is then used to restrict access to "formal" polls, etc. This method would need to capture some identifying information (full name etc.) as a formal statement by an unknown person probably doesn't amount to much.

(1) is apparently the more robust method, but raises a higher number of privacy and data protection issues. It also requires a considerable amount of work (receiving and processing 1000, 2000 or more physical letters with enclosed documents, verifying them and allocating a code/password). (2) would be seemingly less robust - put simply people could lie. The level of control is based only in the integrity of individuals to respond honestly to whatever question we might put to them. There remains a data privacy/protection issue in capturing this information at all.

Remembering that the theoretical objective would be to verify beyond doubt that any particular site-member really is a depositor but without having to capture nor store any personal information about that person, which of these two methods is optimal, or is there some other hybrid or other scheme that would be preferable?

This is being posted in focus and all members.