func authenticateNode(accessKey, secretKey, audience string) (string, error) {
	claims := xjwt.NewStandardClaims()
	claims.SetExpiry(UTCNow().Add(defaultInterNodeJWTExpiry))
	claims.SetAccessKey(accessKey)
	claims.SetAudience(audience)

	jwt := jwtgo.NewWithClaims(jwtgo.SigningMethodHS512, claims)
	return jwt.SignedString([]byte(secretKey))
}

// Check if the request is authenticated.

	return &StandardClaims{}
}

// SetIssuer sets issuer for these claims
func (c *StandardClaims) SetIssuer(issuer string) {
	c.Issuer = issuer
}

// SetAudience sets audience for these claims
func (c *StandardClaims) SetAudience(aud string) {
	c.Audience = aud
}

// SetExpiry sets expiry in unix epoch secs
func (c *StandardClaims) SetExpiry(t time.Time) {
	c.ExpiresAt = t.Unix()
}