Don't use legacy exponent for RSA

As stated in the cryptography.io documentation, "Almost everyone should
use 65537" for the public_exponent in an RSA key. [1]

This patch also uses a larger RSA key length for FIPS compatibility.

[1] https://cryptography.io/en/latest/hazmat/primitives/asymmetric/rsa/#cryptography.hazmat.primitives.asymmetric.rsa.generate_private_key

Change-Id: I9f0c030b172a544821aa42924e4401cd7ccc9956
1 file changed