A secure telephone enables confidential communication between two or more parties using mutual encryption. The parties can also utilize authentication technology to verify their identities before initiating a conversation. Secure telephones are in use at a number of government agencies and offices like embassies, in addition to companies that handle secure or proprietary information and want to make sure it remains confidential. The cost for setting up a system can depend on the type of technology and the level of encryption needed.
Ordinary telephone communications are highly vulnerable to a man in the middle attack, where another party taps into the line to listen in on the conversation. This could pose significant security risks if a conversation involved matters of national security or other sensitive information. With a secure telephone, the devices used by all parties on a call encrypt data on the way out, and decrypt it on the way in, using an encryption key. This can include not just voice but other data transmissions, allowing for transmission of text and video.
Users of secure telephone technology must have compatible systems, which can add to the expense. Organizations may need to maintain multiple systems to communicate with different contacts, or could need an overhaul to get current with a partner agency. Each system may use different methods to handle data, which means that competing products are often not compatible. One way around this is the use of secured communication on voice over Internet protocol (VoIP) technology, where users need software programs, rather than entire hardware systems, to secure their communications.
Some secure telephone models also provide room for authentication. This allows users to exchange keys to verify their identities before the phone call takes place, to limit the possibility of impersonation or spoofing. Authentication is usually necessary when parties on a phone call have the capability to authorize significant decisions, such as a launch of nuclear weapons. People on all sides want to make sure they are talking to the right people, and can exchange authentication information as well as unique codes during the call to confirm verbal orders.
Enabling secure communication on mobile devices can be somewhat more challenging, as they are by nature easier to sniff with devices that can harvest wireless signals. If the encryption is not sufficient, a hacker may be able to break it and listen in on conversations. This can be a concern for government officials who want to be reachable by secure telephone, and cannot always rely on landline access.