code: func (h finishedHash) serverSum(masterSecret []byte) []byte {
  	if h.version == VersionSSL30 {
  		return finishedSum30(h.serverMD5, h.server, masterSecret, ssl3ServerFinishedMagic[:])
  	}
  
  	out := make([]byte, finishedVerifyLength)
  	h.prf(out, masterSecret, serverFinishedLabel, h.Sum())
  	return out
  }
docs: // serverSum returns the contents of the verify_data member of a server's
  // Finished message.