2. Voynich Manuscript: A 204-page volume, probably dating back to the 1500s, which contains mysterious symbols and drawings. Does it contain the recipe for the elixir of life, or perhaps the secret for turning lead into gold, or is it just a hoax?
3. Indus Valley Script: Some people claim that they know the meaning of the symbols that were used by the Indus Valley civilisation, but has anybody really mastered its subtleties?
4. Genetic Code: Not a coded message in the conventional sense but one that holds the recipe for life.
5. RSA: If you have ever bought something over the Internet, then your credit card details were probably protected with the help of the RSA cipher. Luckily nobody can crack it—yet.
6. Quantum Cryptography: The ultimate code, unbreakable according to the laws of physics. The technology exists and a Swiss company is already selling ciphers that rely on quantum physics and the uncertainty principle.
Simon Singh is author of ‘The Code Book’: www.simonsingh.com
