Go Nonce Generator

Does this function only ever return "AAAAAAAAAAAAAAAAAAAAAAAA"?

func generateNonce() string {
    b := make([]byte, 15)
    rand.Read(b)
    en := base32.StdEncoding
    d := make([]byte, en.EncodedLen(len(b)))
    en.Encode(d, b)
    return string(d)
}