am 4f8c8bdc: am 7689ed6e: ECIES: add HKDF (specified in RFC 5869) using HMAC-SHA256

* commit '4f8c8bdc65c64c84b9bf8e9f9e7b05a48ce8f7b3':
  ECIES: add HKDF (specified in RFC 5869) using HMAC-SHA256