krypton-ios

iPhone 5Ss are great to keep around, you can generate an ECC private key inside the secure enclave (albeit only using the NIST P256 curve). Using Krypton[0] or your own software you can use the phone as a hardware private key. Krypton includes support for SSH, gpg signed git commits, and soon generic gpg signing[1], all backed by TouchID or your passphrase[2]. Make sure to setup Krypton with the "Nist P256 (Secure Enclave)" curve. Private keys generated in the Secure Enclave are only possible to extract using a zero-day in the Secure Enclave coprocessor. [0] https://krypt.co [1] https://github.com/kryptco/krypton-ios/pull/95 [2] Protip: iOS passphrases consisting of only digits will use a keypad on the unlock screen.

I really liked this but the notification requirement on iOS killed it for me. I can’t remember the exact details but it is (roughly) not possible to suppress authorization request notifications because on iOS notifications are the only way to wake-up a backgrounded application. Net result is a notifications every single time krypt authorizes via your phone. This may not be a problem for many people but it drove me nuts. It is unbearable if you use auto-complete on the command line in eg SCP. Edit: typos Edit 2: related issue https://github.com/kryptco/krypton-ios/issues/75