A Caesar cipher is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in a text is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on.
The method is named after Julius Caesar, who used it in his private correspondence. the Caesar cipher is easily broken and in modern practice offers essentially no communication security.
The philosopher's stone is a legendary alchemical substance capable of turning base metals such as mercury into gold or silver. For many centuries, it was the most sought-after goal in alchemy.