code: func verifyHostKeySignature(hostKey PublicKey, result *kexResult) error {
  	sig, rest, ok := parseSignatureBody(result.Signature)
  	if len(rest) > 0 || !ok {
  		return errors.New("ssh: signature parse error")
  	}
  
  	return hostKey.Verify(result.H, sig)
  }
docs: // verifyHostKeySignature verifies the host key obtained in the key
  // exchange.