| 摘要 |
First and second applications are executed in a red domain, and a third application is executed in a black domain, of lower security level, and through which an encrypted communication tunnel passes between the first and second applications. The first application transmits to the second application a nominal sequence of packets ordered depending on their respective sizes; said nominal sequence is intercepted by the third application which, when it wants to transmit information to the red domain, modifies said nominal sequence by removing at least one packet, whether a packet is removed or not depending on said information; on reception of a sequence of packets, which sequence is assumed to be the nominal sequence of packets, the second application verifies whether at least one packet has been removed; and, if such is the case, the second application deduces said information from the size of each packet thus removed. |
