Leaking Out of Information Due to Electromagnetic Infiltration and Its Favourable Circumstances

Electronic devices belong to an indispensable component of present civilisation. They have been processing a wide spectrum of information (from entertainment, through medical and military data to important state matters). Each such operating device generates electromagnetic field which often is an unwanted side effect. In some cases such radiation can include information about data processed by a system what creates a potential risk of the loss of confidentiality. Depending on the rank of a compromised system the disclosed information can cause serious consequences, such as: losses of property, and even of health or human life. Presented paper describes the disclosing emissionsand indicates the factors which have to be taken into account at calculation of a safe level of emission for teleinformative systems.