Pass phrase in memory. Decrypt a message

[DenBond7]

as a part of #372

[tomholub]

This one is the most important of similar issues.

[DenBond7]

@tomholub Let me ask you a few questions about the logic.

When we noticed the NEED_PASSPHRASE error what should we do?

1. show a dialog where we will provide all keys that have missed passphrase
2. show a dialog where we will provide only a key that has missed passphrase and we need that key for decryption

[tomholub]

Option 2 is definitely better

[DenBond7]

@tomholub

Let's imagine that we try to decrypt some message and receive the following error

{
  "type": "decryptErr",
  "content": "---...---",
  "decryptErr": {
    "success": false,
    "error": {
      "type": "need_passphrase",
      "message": "Missing pass phrase"
    },
    "longids": {
      "message": [
        "D7A3DEDB65CB1EFB",
        "4F1458BD22B7BB53"
      ],
      "matching": [
        "3DEBE9F677D5B9BB38E5A244225F8023C20D0957"
      ],
      "chosen": [],
      "needPassphrase": [
        "3DEBE9F677D5B9BB38E5A244225F8023C20D0957"
      ]
    },
    "isEncrypted": true
  },
  "complete": true
}

What about needPassphrase: can we have more than 1 element here?

[tomholub]

possibly. if the message was encrypted for two keys, and you have both, and both are missing pass phrase. in that case, you only need pass phrase for any one of the two to decrypt the message.

…

On Thursday, June 3, 2021, Den ***@***.***> wrote: @tomholub <https://github.com/tomholub> Let's imagine that we try to decrypt some message and receive the following error { "type": "decryptErr", "content": "---...---", "decryptErr": { "success": false, "error": { "type": "need_passphrase", "message": "Missing pass phrase" }, "longids": { "message": [ "D7A3DEDB65CB1EFB", "4F1458BD22B7BB53" ], "matching": [ "3DEBE9F677D5B9BB38E5A244225F8023C20D0957" ], "chosen": [], "needPassphrase": [ "3DEBE9F677D5B9BB38E5A244225F8023C20D0957" ] }, "isEncrypted": true }, "complete": true } What about needPassphrase: can we have more than 1 element here? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1251 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABQDZEKZUZLBK27WGH5JGG3TQ54XVANCNFSM45RQHNWQ> .

-- -- Tom James Holub <http://holub.me/>

[DenBond7]

@tomholub One more question. Is there a situation when we have the following:
decryptErr.error.type == need_passphrase && decryptErr.longids.needPassphrase.size == 0?

[DenBond7]

Need to add tests for the following cases

• Found 1 key without a passphrase
• Found more than 1 key without a passphrase( we only need a passphrase for any one of that keys to decrypt
  the message).
• Test "Fix" button
• test an empty passphrase
• test a wrong passphrase
• test a correct passphrase
• a user doesn't provide the right key

[tomholub]

@tomholub One more question. Is there a situation when we have the following:
decryptErr.error.type == need_passphrase && decryptErr.longids.needPassphrase.size == 0?

That shouldn't happen. You could make an acra report for this.

[DenBond7]

I've found an interesting behavior. Let me provide steps:

1. I have 7 private keys with the option pass phrase in RAM(one of them is 3DEBE9F677D5B9BB38E5A244225F8023C20D0957). There are no provided pass phrases in RAM
2. I open some encrypted message that was encrypted for 3DEBE9F677D5B9BB38E5A244225F8023C20D0957. Then I receive the following error

{
  "type": "decryptErr",
  "content": "---...---",
  "decryptErr": {
    "success": false,
    "error": {
      "type": "need_passphrase",
      "message": "Missing pass phrase"
    },
    "longids": {
      "message": [
        "D7A3DEDB65CB1EFB",
        "4F1458BD22B7BB53"
      ],
      "matching": [
        "3DEBE9F677D5B9BB38E5A244225F8023C20D0957"
      ],
      "chosen": [],
      "needPassphrase": [
        "3DEBE9F677D5B9BB38E5A244225F8023C20D0957"
      ]
    },
    "isEncrypted": true
  },
  "complete": true
}

3. Now I can show a dialog where a user can provide a pass phrase for 3DEBE9F677D5B9BB38E5A244225F8023C20D0957
4. Then go to Settings -> Keys -> Open 3DEBE9F677D5B9BB38E5A244225F8023C20D0957 -> Delete it. Now we have 6 keys.
5. Go to Android Settings -> Apps -> FlowCrypt -> Force stop. we need it to restart Node.js server. To prevent cache issues.
6. Go to the app, open a message from 2. Please let me reminder that message was encrypted for 3DEBE9F677D5B9BB38E5A244225F8023C20D0957 which was deleted in step 4.
7. Now I see the following error

{
  "type": "decryptErr",
  "content": "---...---",
  "decryptErr": {
    "success": false,
    "error": {
      "type": "need_passphrase",
      "message": "Missing pass phrase"
    },
    "longids": {
      "message": [
        "D7A3DEDB65CB1EFB",
        "4F1458BD22B7BB53"
      ],
      "matching": [
        "868AD9D0A54CF0E8A188D4820BF67A84CAB84A5A",
        "39202AB83667ADF3AC87E28AEFE0DFD8E30D9F23",
        "9D23DCD96224DED21A5C1AB38C0661EEF4B22DCD",
        "3A5BCBE96D1FEABE7E3CA91E732201290C68E3DA",
        "27EB4C42D3AC343D4C9EDA8740A2DD702DD0CD1E",
        "C223AF94FA02D2F3465A64670F610EA685B111FA"
      ],
      "chosen": [],
      "needPassphrase": [
        "868AD9D0A54CF0E8A188D4820BF67A84CAB84A5A",
        "39202AB83667ADF3AC87E28AEFE0DFD8E30D9F23",
        "9D23DCD96224DED21A5C1AB38C0661EEF4B22DCD",
        "3A5BCBE96D1FEABE7E3CA91E732201290C68E3DA",
        "27EB4C42D3AC343D4C9EDA8740A2DD702DD0CD1E",
        "C223AF94FA02D2F3465A64670F610EA685B111FA"
      ]
    },
    "isEncrypted": true
  },
  "complete": true
}

8. After that I have to show a dialog where I will display 6 keys and ask a user to provide a passphrase for any of them. But there is no key that can decrypt the message from 2.
9. I thought there should be an error that a user doesn't provide the right key. Is there a bug on the Node side?

[tomholub]

I thought there should be an error that a user doesn't provide the right key. Is there a bug on the Node side?

It's expected behavior as far as when it was designed, but I think we could start considering it a bug today.

Sometimes you may receive a message that was badly constructed: it's encrypted for your key A, but it says it's encrypted for B and C.

You have no key B or C, you only have A and it looks like you cannot decrypt the message because of key mismatch. But when you actually enter the pass phrase for A, and try decryption, it will decrypt.

---

This situation results from an error on sender side and therefore we don't have to support it anymore.

I'll see if I can easily change it in NodeJS.

[DenBond7]

The final version

[DenBond7]

[tomholub]

Looks good. "missed pass phrase" -> "missing pass phrase" :-)

[DenBond7]

I'm going to add a few tests and this issue will be completed.