Title: Cryptography in a quantum world
| Speaker: | Gilles Brassard |
| Affiliation: | Université de Montréal |
| Location: | MC 5501 |
| Reception: | MC 5511 |
Abstract:
Cryptography, although practised as an art and science for thousands of years, had to wait until the end of the 1940s before Claude Shannon gave it a strong mathematical foundation. However, Shannon's approach was rooted in his own information theory, itself inspired by the classical physics of Newton. But our world is ruled by the laws of quantum mechanics. When quantum-mechanical phenomena are considered, new vistas open up both for code makers and code breakers. Some theorems (including by Shannon) remain mathematically correct, but become irrelevant in our quantum world. Most strikingly, it is possible for two people who do not share ahead of time a long secret key to communicate in perfect secrecy under the nose of an eavesdropper with unlimited computing power and whose technology is limited only by the known laws of physics. Conversely, quantum mechanics provides powerful tools to threaten the mechanisms that are currently used on the Internet to protect electronic transactions. Furthermore, it seems -- but is not yet proven -- that quantum mechanics provides more benefits to code breakers than to code makers if the latter are restricted to using only classical communication channels. So, in the end, is quantum mechanics a blessing or a curse to the protection of privacy? The jury is still out.
No prior knowledge in quantum mechanics or cryptography will be expected from the audience.