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rnpgp / rnp

RNP: high performance C++ OpenPGP library used by Mozilla Thunderbird
https://www.rnpgp.org
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Choose the latest encryption-capable subkey by default. #1313

Closed ni4 closed 4 years ago

ni4 commented 4 years ago

Description

Currently, when encrypting data to the primary key which is not able to encrypt, rnp chooses the first encryption-capable 'good' subkey. However, it could be more wise to choose the latest one. See the discussion/report here:

https://thunderbird.topicbox.com/groups/e2ee/T12a8f43ab17206ec-M835b2ddbba1b0dfe3ec85cb5/tb-native-openpgp-implementation-does-not-use-newer-subkeys

nwalfield commented 4 years ago

As I argue in that thread, it would be better to encrypt to all valid subkeys.

ni4 commented 4 years ago

@nwalfield Imho this would be too strict default behavior as for library level (and effectively lowering security level to the less secure subkey). Implementation, which uses RNP, still able to pick any number of subkey(s) used for encryption. So it could have checkmark like 'Use all available subkeys for encryption' making this configurable.

nwalfield commented 4 years ago

As I argue there, your policy actually lowers the security, because it means that all keys need to be available on all devices. By encrypting to all, it is possible to generate and store keys on TPMs. If security is a concern, it is better to retire old keys.