Bugfix
   * Fix ECDSA verification, where it was failing to validate the public key
     for signatures where R == 1 and S == 1. This bug meant that it was
     possible to verify such signatures with an invalid public key, in some
     cases.

Bugfix
   * Fix ECDSA verification, where it was not always validating the
     public key. This bug meant that it was possible to verify a
     signature with an invalid public key, in some cases. Reported by
     Guido Vranken in #4420.

Improve changelog for ECDSA verify fix
Improve changelog for ECDSA verify fix

Signed-off-by: Dave Rodgman <c7ff43d67af1dd23561452e7410f0b0fcc98e527@arm.com>
