I'm about to encourage a group of people to begin using S-Mime and GPG for digital signatures and encryption. I foresee a nightmare of encrypted documents which can no longer be recovered because of lost keys.

The thorniest issue is archiving. The natural way to preserve privacy in an archive is to archive the encrypted document.

But that opens us up to the risk of a lost key when time comes to unarchive a document, or a forgotten password. After all it will be a long way in the future. This would be equivalent to having destroyed the document.

First thought is archiving keys with documents, but that still leaves the forgotten pass phrase. Archiving the passphrase too would be tantamount to archiving in the clear. No privacy.

What approaches do you use? What insights can you offer on the issue?