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Instead of saving your seed phrase in a secure element, Krux lets you encrypt it (AES-CBC, PBKDF2 Iterations: 100,000 or more) using as strong of a decryption key as you want, and Krux can save the encrypted seed on a micro SD card (I don't) or as an encrypted QR code (yes!). However you save it, you'll need your decryption key to decrypt it.
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I find Krux's purpose interesting. I wonder if it's possible to decrypt the encrypted file or QR code of your seed outside of Krux? That is, via the command line, because the algorithm used is AES-CBC, which is already built into Linux...
And if you use BIP85, you can use the text from child seed phrases as passphrases or decryption keys, which means it's all deterministic and recoverable if lost.
Are you referring to using the BIP-85 child seeds generated by passphrase and using them as a second or third layer of additional protection? If not, I don't understand...