user concern: Error: Your account keys are not usable for encryption

[martgil]

Description: The following error appears when the user tries to send or save draft messages.

Error: Your account keys are not usable for encryption

user pubkey: https://flowcrypt.com/attester/pub/BDAF70C5F5261B98

Reference: https://mail.google.com/mail/u/human@flowcrypt.com/#inbox/FMfcgzGrcjWwVVhxlLmgVmvXWtkHnGjv

[martgil]

I did check pubkey for common error/issue and found this warning:

Got error performing encryption/decryption test: Error: Error encrypting message: Could not find valid encryption key packet in key bdaf70c5f5261b98: elgamal keys are considered too weak.

The subkey algorithm is indeed elgamal. So one way to solve this is to encourage the user to generate a new key with a stronger key algorithm? eg RSA 4098

[martgil]

Another user experienced the same problem except the this particular users uses an RSA 2048 - users public key: https://flowcrypt.com/attester/pub/6E2AC39E5643EFB9

reference: https://mail.google.com/mail/u/human@flowcrypt.com/#inbox/FMfcgzGrcrpvrZfBlgQTCHHHZnTmvmph

[tomholub]

I did check pubkey for common error/issue and found this warning:

Got error performing encryption/decryption test: Error: Error encrypting message: Could not find valid encryption key packet in key bdaf70c5f5261b98: elgamal keys are considered too weak.

The subkey algorithm is indeed elgamal. So one way to solve this is to encourage the user to generate a new key with a stronger key algorithm? eg RSA 4098

Yes, ideally we recommend curve25519

[tomholub]

Another user experienced the same problem except the this particular users uses an RSA 2048 - users public key: https://flowcrypt.com/attester/pub/6E2AC39E5643EFB9

Could you post the whole key compatibility test output for this one?

[martgil]

Here is the output from the key compatibility test for 6E2AC39E5643EFB9:

(1) Primary keys found: 1  
(2) ----- Testing key 0 -----  
(3) PK 0 > Key type: openpgp  
(4) PK 0 > Is Private?: [-] false  
(5) PK 0 > User id 0: User <user@example.com>  
(6) PK 0 > Primary User: User <user@example.com>  
(7) PK 0 > Fingerprint: B01B FC16 C6B3 B0FB 44B6 D9DE 6E2A C39E 5643 EFB9  
(8) PK 0 > Subkeys: [-] 1  
(9) PK 0 > Primary key algo: [-] rsaEncryptSign  
(10) PK 0 > Usage flags: [-] [sign_data, certify_keys]  
(11) PK 0 > Primary key verify: [-] valid  
(12) PK 0 > Primary key creation?: [-] 1554352213 or 2019-04-04T04:30:13.000Z  
(13) PK 0 > Primary key expiration?: [-] -  
(14) PK 0 > Encrypt/Decrypt test: Encryption with key was successful:   
(15) PK 0 > Encrypt/Decrypt test: Skipping decryption because isPrivate:false isFullyDecrypted:unknown:   
(16) PK 0 > SK 0 > LongId: [-] 3624202B8271A3F4  
(17) PK 0 > SK 0 > Created: [-] 1554352225 or 2019-04-04T04:30:25.000Z  
(18) PK 0 > SK 0 > Algo: [-] rsaEncryptSign  
(19) PK 0 > SK 0 > Usage flags: [-] [encrypt_communication, encrypt_storage]  
(20) PK 0 > SK 0 > Verify: [-] OK  
(21) PK 0 > SK 0 > Subkey object type: [-] PublicSubkeyPacket  
(22) PK 0 > SK 0 > Subkey getBitSize: [-] 2048  
(23) PK 0 > SK 0 > Subkey decrypted: [-] null  
(24) PK 0 > SK 0 > Binding signature length: [-] 1  
(25) PK 0 > SK 0 > SIG 0 > Key flags: [-] 12  
(26) PK 0 > SK 0 > SIG 0 > Version: [-] 4  
(27) PK 0 > SK 0 > SIG 0 > Public key algorithm: [-] 1  
(28) PK 0 > SK 0 > SIG 0 > Sig creation time: [-] 1554352241 or 2019-04-04T04:30:41.000Z  
(29) PK 0 > SK 0 > SIG 0 > Sig expiration time: [-] -  
(30) PK 0 > SK 0 > SIG 0 > Verify: [-] valid  
(31) PK 0 > expiration: [-] undefined  
(32) PK 0 > internal dateBeforeExpiration: [-] undefined  
(33) PK 0 > internal usableForEncryptionButExpired: [-] false  
(34) PK 0 > internal usableForSigningButExpired: [-] false 

When trying to reply (encrypted) to the user's email, the following error appears:

reference: https://mail.google.com/mail/u/human@flowcrypt.com/#inbox/FMfcgzGrcrpvrZfBlgQTCHHHZnTmvmph

[tomholub]

Could you please update that script to include two more lines?

PK 0 > internal usableForEncryption
PK 0 > internal usableForSigning

at the end. Then re-run the compatibility test (and open a new PR that adds these two fields)

[martgil]

result for BDAF70C5F5261B98 and 6E2AC39E5643EFB9 shows:

PK 0 > internal usableForEncryption: [-] false  
PK 0 > internal usableForSigning: [-] false 

I tried encrypting messages with these public keys using gpg and haven't got errors.

[martgil]

Another case yet different from the previous ones. This one has a rsa2047 subkey :

public key: AB74489E17786D24

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: FlowCrypt 1.3.9 Gmail Encryption
Comment: Seamlessly send and receive encrypted email
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=K1r9
-----END PGP PUBLIC KEY BLOCK-----

compatibility test output:

(1) Primary keys found: 1  
(2) ----- Testing key 0 -----  
(3) PK 0 > Key type: openpgp  
(4) PK 0 > Is Private?: [-] false  
(5) PK 0 > User id 0: <user@example.com> 
(6) PK 0 > Primary User: <user@example.com> 
(7) PK 0 > Fingerprint: 581A D1FD 271F 8A7E 22D9 BF17 AB74 489E 1778 6D24  
(8) PK 0 > Subkeys: [-] 1  
(9) PK 0 > Primary key algo: [-] rsaEncryptSign  
(10) PK 0 > Usage flags: [-] [sign_data, certify_keys]  
(11) PK 0 > Primary key verify: [-] valid  
(12) PK 0 > Primary key creation?: [-] 1563140972 or 2019-07-14T21:49:32.000Z  
(13) PK 0 > Primary key expiration?: [-] -  
(14) PK 0 > Encrypt/Decrypt test: Got error performing encryption/decryption test: Error: Error encrypting message: Could not find valid encryption key packet in key ab74489e17786d24:   
(15) PK 0 > SK 0 > LongId: [-] B548F516C1364901  
(16) PK 0 > SK 0 > Created: [-] 1563141107 or 2019-07-14T21:51:47.000Z  
(17) PK 0 > SK 0 > Algo: [-] rsaEncryptSign  
(18) PK 0 > SK 0 > Usage flags: [-] []  
(19) PK 0 > SK 0 > Verify: [-] OK  
(20) PK 0 > SK 0 > Subkey object type: [-] PublicSubkeyPacket  
(21) PK 0 > SK 0 > Subkey getBitSize: [-] 2047  
(22) PK 0 > SK 0 > Subkey decrypted: [-] null  
(23) PK 0 > SK 0 > Binding signature length: [-] 1  
(24) PK 0 > SK 0 > SIG 0 > Key flags: [-] 12  
(25) PK 0 > SK 0 > SIG 0 > Version: [-] 4  
(26) PK 0 > SK 0 > SIG 0 > Public key algorithm: [-] 1  
(27) PK 0 > SK 0 > SIG 0 > Sig creation time: [-] 1563141469 or 2019-07-14T21:57:49.000Z  
(28) PK 0 > SK 0 > SIG 0 > Sig expiration time: [-] -  
(29) PK 0 > SK 0 > SIG 0 > Verify: [-] valid  
(30) PK 0 > expiration: [-] undefined  
(31) PK 0 > internal dateBeforeExpiration: [-] undefined  
(32) PK 0 > internal usableForEncryption: [-] false  
(33) PK 0 > internal usableForSigning: [-] false  
(34) PK 0 > internal usableForEncryptionButExpired: [-] false  
(35) PK 0 > internal usableForSigningButExpired: [-] false  

Interesting output from the tester:

(18) PK 0 > SK 0 > Usage flags: [-] []
(32) PK 0 > internal usableForEncryption: [-] false

subkey's usage flag wasn't detected on the compatibility tester but detected the usage: E is shown in gpg. Encryption is failing on gpg though.

Reference: https://mail.google.com/mail/u/human@flowcrypt.com/#inbox/FMfcgzGrcrvhSlnwXWFBqzFSHPZfVjnF

[tomholub]

if gpg also fails on it, chances are, it's really a problematic key.

[martgil]

if gpg also fails on it, chances are, it's really a problematic key.

For AB74489E17786D24 case, we should encourage the user to generate a new key instead?

For BDAF70C5F5261B98 and 6E2AC39E5643EFB9, I can encrypt messages using them. Key usage flags are correctly detected by the compatibility tests and gpg.

[tomholub]

For AB74489E17786D24 case, we should encourage the user to generate a new key instead?

If gpg fails on it, then yes.

For BDAF70C5F5261B98 and 6E2AC39E5643EFB9, I can encrypt messages using them. Key usage flags are correctly detected by the compatibility tests and gpg.

It would be good to know the algorithm and bits of the primary key, similar to a recently discussed issue. If the bits are below 2048 on the primary key, that may explain it.

Are you able to use these two keys with OpenPGP.js directly?