As mentioned in the comments, plain text keys aren’t bad because they are necessary. You have to have at least one plain text key in order to be able to use encryption
12 points
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How does that help when somebody has access to the phone via your PIN or password?
4 points
If I’m not mistaken you can save keys in these chips so that they can not be extracted. You can only use the key to encrypt/decrypt/sign/verify by asking the chip to do these operations with your key.
5 points
That sounds only marginally better. Access to the phone still means you can create a backup containing the key, so TPM wouldn’t help much.
1 point
3 points
No, why would a backup contain non-exportable information? One of the reasons to use TPM to begin with is that sensitive information can’t leave it.
