JarUtils: try using the DigestEncryptionAlgorithm

The original code tried getting an instance of the DigestAlgorithm by
itself as a Signature type. This appears meant to be the
DigestEncryptionAlgorithm by itself. Algorithms such as SHA256withECDSA
have their own OID.

Change-Id: I9384127bb026c8a5d3956095a9880427ead366b4
3 files changed