7. Glossary – Definitions

Side channel attack

Attack that does not concern the theoretical security method. It seeks out and exploits weaknesses in the practical means of implementation: human procedure, external behavior (computing time) of software or hardware (electromagnetic radiation, noise).

Vernam cipher/one-time pad

Symmetrical encryption based on the use of the XOR (exclusive OR) logic function, using unique (ephemeral) keys made of random bits that are the same size as the messages. This encryption has been shown to be tamper-proof (ITS), but difficult to implement due to the impossibility of truly secretly exchanging the encryption keys used (or disposable masks) between sender and receiver.

Forward secrecy

Term used in the QSC white paper, cryptographic property...