recognize prv backup and show details

[tomholub]

#1621

Similar to pubkey
allow user to test their pass phrase, say the pass phrase is needed, etc

[tomholub]

Michael,

I get many emails similar to:

How do I open the backup? I tried to open it but don't know how.

To that I respond:

Hello,
you don't have to view or open the backup. Feel free to just archive it.
To verify that your account is backed up properly, please go to FlowCrypt Settings -> Backup. It should say "your account is backed up correctly".
It is however important to record your pass phrase properly. To verify that you remember it correctly, please go to FlowCrypt Settings -> Security -> Test my pass phrase.
After that, please note your pass phrase down on a paper. It will be useful if your device ever stops working and you need to get set up on a new one.

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Solution: let's start displaying details about backups, similar to how we recognize and render details about attached public keys.
The work will be somewhere around replaceAtts
pgpNamePatterns could maybe start returning one big RegEx instead of a list of strings. Then filterAtts could be simplified a lot.
Example, backups can be recognized with: (cryptup|flowcrypt)-backup-[a-z]+\.key
Once you recognize a backup file, you treat it similar to a pubkey. But instead of pgp_pubkey.htm frame you would insert pgp_backup.htm (a new iframe type).

---

The frame will look something like this:

This message includes a Public Key backup for some@email.com.

Private key is needed to open your encrypted messages.

Your pass phrase is needed if you ever need import this backup in the future (for example, when setting up FlowCrypt on another device, or when your main device stops working). 

Test that you remember your pass phrase correctly:
[ passphrase _______________  ][ø]   [ TEST PASSPHRASE]  // green btn

KeyWords: SOUP PADDLE MERGE INSIDE SKILL ATTACK // pull from the key
(Fingerprint: 5C42 AD03 B8AA 743A FB13 7C1B CFF3 DA2D BA9C A673) // pull from key

// bottom

Then, on the very bottom, it will either say

This key is already imported.

or

This private key was not imported. We suggest to import all backups so that you can read all incoming encrypted emails.

[IMPORT MISSING PRIVATE KEY] // green btn

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You can figure out if the key was already imported by extracting primary longid from the backup, and trying to find a key with the same longid in local private key storage:

const backupKeyLongid = await Pgp.key.longid(backup);
const [matchingStoredKey] = await Store.keysGet(acctEmail, backupKeyLongid);
if(matchingStoredKey) { ... } else { ... }

The IMPORT MISSING PRIVATE KEY could simply lead to settings/add_key.htm page, which you can open by sending a message requesting it to open:

BrowserMsg.send.bg.settings({ acctEmail, page: '/chrome/settings/modules/add_key.htm' })

Which should result in an acceptable user experience - you need to test it and let me know.

---

Also remember to add pgp_backup.htm into web accessible resources in manifest, plus also test this in Setings -> Encrypted Inbox.

This issue is quite involved, so feel free to ask questions.

[tomholub]

There's something I didn't notice when merging it. The backup frame is replacing the whole message, which is not good. It's supposed to be added under the original message, like public key:

Backup (message wrongly replaced)

Backup (before replacing)

Further, when you go to FlowCrypt Settings -> Encrypted Inbox, the backup doesn't show at all.

@michael-volynets please fix this before working on any other issue.

[michael-volynets]

Okay, I'm looking at it.