Van Eck phreaking是指通过侦测显示器(CRT或LCD)发出的电磁辐射，来窃听其内容。Van Eck phreaking这一名字来自荷兰计算机研究员Wim van Eck，是他在1998年最早发表了有关这一技术的论文，包括proof of concept。Phreaking这一词的意思是指利用电话网络的漏洞，在这里使用是因为它的意思跟窃听有关。

Van Eck phreaking有可能会威胁使用到电子投票系统的选举的安全性。这导致荷兰政府禁止在2006年的国家选举中使用SDU制造的NewVote电子投票机器，因为他们认为投票的信息可能被人窃听。

TEMPEST is a National Security Agency specification and a NATO certification referring to spying on information systems through leaking emanations, including unintentional radio or electrical signals, sounds, and vibrations. TEMPEST covers both methods to spy upon others and also how to shield equipment against such spying. The protection efforts are also known as emission security (EMSEC), which is a subset of communications security (COMSEC).