What is the difference between money and virtual currencies? What is symmetrical and asymmetrical encryption? How did Bitcoin come about, and does it have any future? Our maths teacher Pavol Gálik, who has long-term experience with cryptography, talked to us about virtual currencies, electronic signatures, hash functions, and about what makes Bitcoin so expensive, and also its advantages. Mr Galik used to work for Telekom and Tatra Banka.