Key generator uses RSA PKCS#1 v1.5 padding

[sethkraut]

The key generator uses RSA PKCS#1 v1.5 padding, which has security issues. RSA Optimal Asymmetric Encryption Padding (OAEP) appears to be a better choice. Is it possible to switch or to allow configuration of the padding?

RealWhorlwind.java:155

[mattprecious]

Looks like it would require bumping the min SDK to 23: https://developer.android.com/training/articles/keystore#SupportedAlgorithms

[jbryan26]

Is there any reason not to use the stronger padding and then fall back to the weaker padding if the build version is lower? I noticed in the RealWhorlwind.java file there is already a check to see if the fingerprint or biometric permission should be used. Something similar could work for the padding. I can submit a PR if that would help.

Edit:
And it appears that this class requires 23:

@RequiresApi(Build.VERSION_CODES.M)
final class RealWhorlwind extends Whorlwind {