parsing of several keys at a time in Kotlin + expect potentially encrypted keys

[tomholub]

as a part of #1051 but only after #1052

In our Pgp.kt implementation https://github.com/FlowCrypt/flowcrypt-email-key-manager/blob/2f62df069eee4e6b229d5faef21944696d332068/shared-lib/src/main/kotlin/com/flowcrypt/shared/crypto/Pgp.kt#L187 we assume that we are parsing a single key each time, and the key - if it's a private key - must be decrypted.

However here on client side we may encounter many keys in a single armored block, or many keys in a single byte array stream (unarmored) so we need a way to parse and return an array.

The current implementation is at https://github.com/FlowCrypt/flowcrypt-mobile-core/blob/f80d5491451b61dcf8e539932b693fb28e84217f/source/mobile-interface/endpoints.ts#L229 :

  public parseKeys = async (_uncheckedReq: any, data: Buffers) => {
    const keyDetails: KeyDetails[] = [];
    const allData = Buf.concat(data);
    const pgpType = await PgpMsg.type({ data: allData });
    if (!pgpType) {
      return fmtRes({ format: 'unknown', keyDetails });
    }
    if (pgpType.armored) {
      // armored
      const { blocks } = MsgBlockParser.detectBlocks(allData.toString());
      for (const block of blocks) {
        const { keys } = await PgpKey.parse(block.content.toString());
        keyDetails.push(...keys);
      }
      return fmtRes({ format: 'armored', keyDetails });
    }
    // binary
    const { keys: openPgpKeys } = await openpgp.key.read(allData);
    for (const openPgpKey of openPgpKeys) {
      keyDetails.push(await PgpKey.details(openPgpKey))
    }
    return fmtRes({ format: 'binary', keyDetails: keyDetails });
  }

It tries to infer the type of the message key it starts parsing, and then it parses either armored keys or binary keys flexibly, and returns a list of parsed keys.

[IvanPizhenko]

@DenBond7 what do you think, which package should go this one?

[IvanPizhenko]

ah, stop, I have recently created myself some "pgp" package, so I think I will put it there.

[IvanPizhenko]

@tomholub @DenBond7 Does anyone know - how openpgp.js class Key maps to BouncyCastle? Is it key or keyring object? I currently assume it is single key (i.e. not a keyring).
But by presence of the fields "isFullEncrypted" and "isFullyDecrypted" in the KeyDetails, which is created from Key I start thinking it could be a BouncyCastle's keyring.

[tomholub]

Key is what you generally can get when you parse an armored OpenPGP key. That may contain a master key packet and a bunch of subkey packets that are bound to that master key packet. It also has encoded in it the public key counterpart in case it was a private key.

So always one master key packet + zero or more subkey packet (and maybe some equivalent public key packets? Or these get recomputed?) and possibly a bunch of related signature packets or maybe user id packets per Key. If there was somehow more than one master key, then you'd be dealing with a Key[].

[tomholub]

Here are details about one sample Key:

(1) Primary keys found: 1
(2) ----- Testing key 0 -----
(3) PK 0 > Key type: openpgp
(4) PK 0 > Is Private?: [-] true
(7) PK 0 > Fingerprint: A925 AB20 AFD0 66E5 7D65 AC0F D9AD 596E 5857 035C
(8) PK 0 > Subkeys: [-] 1
(9) PK 0 > Primary key algo: [-] rsa_encrypt_sign
(10) PK 0 > Usage flags: [-] [sign_data, certify_keys]
(11) PK 0 > key decrypt: [-] false
(12) PK 0 > isFullyDecrypted: [-] false
(13) PK 0 > isFullyEncrypted: [-] true
(14) PK 0 > Primary key verify: [-] valid
(15) PK 0 > Primary key creation?: [-] 1613765823 or 2021-02-19T20:17:03.000Z
(16) PK 0 > Primary key expiration?: [-] -
(17) PK 0 > Encrypt/Decrypt test: Encryption with key was successful:
(18) PK 0 > Encrypt/Decrypt test: Skipping decryption because isPrivate:true isFullyDecrypted:false:
(19) PK 0 > Sign/Verify test: [-] skipped, not fully decrypted
(20) PK 0 > SK 0 > LongId: [-] C2931B28D634C0D2
(21) PK 0 > SK 0 > Created: [-] 1613765823 or 2021-02-19T20:17:03.000Z
(22) PK 0 > SK 0 > Algo: [-] rsa_encrypt_sign
(23) PK 0 > SK 0 > Usage flags: [-] [encrypt_communication, encrypt_storage]
(24) PK 0 > SK 0 > Verify: [-] OK
(25) PK 0 > SK 0 > Subkey tag: [-] 7
(26) PK 0 > SK 0 > Subkey getBitSize: [-] 2048
(27) PK 0 > SK 0 > Subkey decrypted: [-] false
(28) PK 0 > SK 0 > Binding signature length: [-] 1
(29) PK 0 > SK 0 > SIG 0 > Key flags: [-] 12
(30) PK 0 > SK 0 > SIG 0 > Tag: [-] 2
(31) PK 0 > SK 0 > SIG 0 > Version: [-] 4
(32) PK 0 > SK 0 > SIG 0 > Public key algorithm: [-] 1
(33) PK 0 > SK 0 > SIG 0 > Sig creation time: [-] 1613765823 or 2021-02-19T20:17:03.000Z
(34) PK 0 > SK 0 > SIG 0 > Sig expiration time: [-] -
(35) PK 0 > SK 0 > SIG 0 > Verified: [-] true
(36) PK 0 > expiration: [-] undefined
(37) PK 0 > internal dateBeforeExpiration: [-] undefined
(38) PK 0 > internal usableForEncryptionButExpired: [-] false
(39) PK 0 > internal usableForSigningButExpired: [-] false

[IvanPizhenko]

So in the BouncyCastle terms it is PGPKeyRing (either public or secret).

[tomholub]

That sounds correct

[tomholub]

To be more precise, an OpenPGP.js Key may contain a public PGPKeyRing (public only) or a combination of public PGPKeyRing + private PGPKeyRing (for a private key).