In this work, we focus on Single-Input Functionality (SIF), a specialized case of MPC where only one designated party, called the dealer, holds a private input. SIF enables the dealer to perform computations with other parties without disclosing any additional information about the private input. SIF has a wide range of applications, such as multiple-verifier zero-knowledge and verifiable relation sharing. We propose the first 1-round SIF protocol against a dishonest majority in the preprocessing model and random oracle model, achieving high efficiency. Previous works either require at least 2-round online communication (Yang and Wang, Asiacrypt 2022; Baum et al., CCS 2022; Zhou et al., Euro S&P 2024) or are limited to feasibility results (Lepinski et al., TCC 2005; Applebaum et al., Crypto 2022). We also show the necessity of using the broadcast channels, by formally proving that 1-round SIF is impossible to achieve in the preprocessing model, if there are no broadcast channels available. Finally, we implement our protocol and present extensive experimental results, demonstrating its practical efficiency.