Method for encrypting speech on basis of TD-SCDMA (time division-synchronization code division multiple access) circuit domains

The invention discloses a method for encrypting speech on the basis of TD-SCDMA (time division-synchronization code division multiple access) circuit domains. The method includes encrypting uplink AMR (automatic message recording) speech code data by the aid of session keys and encryption message keys, then carrying out channel coding on the encrypted speech code data and transmitting the coded encrypted speech code data via TrFo (transcoder free operation) channels; decrypting downlink encrypted speech data by the aid of the session keys and decryption message keys. The method has the advantages that the problem of incapability of guaranteeing the QoS (quality of service) of encrypted conversation in mobile safety VoIP (voice over internet protocol) encrypted telephone on the basis of packet domains can be effectively solved, and the problem that encrypted speech data cannot be transmitted due to the fact that code converters are arranged on speech channels in mobile communication networks for carrying out speech coding and decoding conversion on speech information transmitted through the coding converters can be effectively solved; mobile speech encryption products encrypted by the aid of the method are good in sound quality and high in network adaptability, the method is free of constraints of user capacity, and the like.