22.3403GPPIP Multimedia Subsystem (IMS) messagingStage 1TS
The user shall be able to use IMS Messaging and access messages in a secure manner. It shall be possible for the contents of messages to be read only by the intended recipient(s). A recipient shall be informed of the reliability of the identity of the sender in case the sender has authorised his identity to be transmitted.
The integrity of messages during transit shall be assured to extent of the network capabilities.
IMS Messaging shall be intrinsically resistant to attempts of malicious or fraudulent use.
The "Security Threats and Requirements" specified in 3GPP TS 21.133  shall not be compromised.