Mac® Security Bible

9.9. Securing Instant Messaging and Voice over IP with Third-Party Software

iChat started out as a text-based instant messaging system and later added audio and video capabilities. Dozens of third-party Mac applications also offer some combination of text, audio, and video chat features. Closely related to audio chat is voice over IP (VoIP). In its broadest sense, VoIP refers to any method of conducting real-time audio conversations over an IP network (such as the Internet), but the term is more often applied to systems that use the Internet to carry audio conversations to or from conventional telephone networks. Most VoIP software lets you use your Mac as a telephone, placing calls to (and/or receiving calls from) regular telephone numbers.

As previously described, iChat lets you encrypt your conversations (of whichever variety) as long as all participants are using MobileMe or .Mac accounts and have encryption enabled. However, most instant messaging and VoIP programs offer no encryption capabilities. Someone with access to Internet traffic between you and another participant could conceivably watch your text messages in real time, listen to the audio of the conversation, and watch the video. The real-world risk of your communication channel being compromised is small, but even so, if you have anything especially sensitive to discuss, an unencrypted digital stream isn't the wisest way to do so.

Unfortunately, most instant messaging and VoIP software doesn't include encryption, ...