Sato Code Zurich: Albert’s Key

Prof. Albert found a way to break any encryption. It was the holy grail of IT security. The discovery was named after him: “Albert's Door”.
The world went crazy about the invention. Every bank, online shop, government could be easily hacked into. But Prof. Albert did not share his discovery with anyone. The turmoil was too much for him. He went into hiding.
But he left Albert's Door to be found by somebody else. There was a trail of puzzles and clues through Zurich. A few people found his clues and discovered the first piece. But the second piece of Albert's Door was missing. Until a few weeks ago when a note appeared:
They are chasing me. I don't have much time. I should have never told the world about it. This was the biggest mistake of my life: Letting the world know about the existence of Albert's Door. Secret services and criminal organisations are chasing me now. They all want absolute power. I cannot let them have it. They would misuse it and ruin the world.
With great power comes great responsibility. I must find the one that I can trust. So, I created a series of puzzles. If you can solve them, you shall find Albert's Key, the key to open Albert's Door. I have faith in you. I believe you will use it for the good of the world.
I must go now. They are close…