Bitcoin is not the first currency using cryptography. There are three others before, I don't remember their name but you can about this on any search engine. Bitcoin itself is using some features from one of this 3 virtual currencies.
Visual cryptography is a cryptographic technique which allows visual information (pictures, text, etc.) to be encrypted in such a way that decryption becomes a mechanical operation that does not require a computer
thanks wikipedia
https://en.wikipedia.org/wiki/Visual_cryptography