Extraits choisis sur http://www.theguardian.com/world/2013/sep/05/nsa-gchq-encryption-codes-security :

• "The document reveals that the agency has capabilities against widely used online protocols, such as HTTPS, voice-over-IP and Secure Sockets Layer (SSL), used to protect online shopping and banking."
• "Through these covert partnerships, the agencies have inserted secret vulnerabilities – known as backdoors or trapdoors – into commercial encryption software."
• "Snowden appeared to confirm this (...) : "Encryption works. Properly implemented strong crypto systems are one of the few things that you can rely on," he said before warning that NSA can frequently find ways around it as a result of weak security on the computers at either end of the communication."

Résumé:

• passer à un chiffrement plus fort (>2048-bit). Par exemple, RSA-1024 semble vraisemblablement cassé. Source: https://www.schneier.com/essay-446.html
• on peut encore faire confiance aux maths - en l'occurrence à la cryptographie si celle-ci est correctement implémentée (PRNG qui génère des nombres vraiment aléatoires) et utilisée sur des machines sures ; ce qui m'ammene au point suivant
• n'accorder aucune confiance aux logiciels privateurs ou aux technologies propriétaires (présence potentielle de backdoor).