Remove DES 112 tests, and speed up RSA keygen

Only DES3 is supported (168-bit), so remove
tests for 112-bit DES.

Also replace the RSA public exponent 3, with
65537 in most tests so that RSA key generation
is faster.

Change-Id: I9958df81fe46d752d82072dc6c7effa34b2921a8