This is to move OTA update package verification logic for new Android
devices from SHA-1 to SHA-256.
Prior to this change the script which generates new signing keys
used SHA-1 in certificates. This change switches the script from SHA-1
to SHA-256. The reason is that OTA updates are accepted only if they
are signed using the same digest algorithm as in the certificate.
Bug: 25643280
Bug: 20580998
Change-Id: I9babe85946a43697aeb4309837504aea25e26763
This script can replace the copies of mkkey.sh sprinkled all over the
tree. It prompts nicely for passwords, avoids writing the raw private
key to disk, and always generates certs that use sha1WithRSAEncryption.
