Vigenere's cipher

This substitution cipher works on the basis of the Caesar cipher. To apply this algorithm, all combinations of Caesar's alphabet (i.e., 26 combinations) are arranged in a "table" of coordinates.
According to the key and the original text, the column and row in the alphabet table are then selected (the key is the same length as plain text, otherwise it must be repeated up to the given length) - the character at the given position in the table is replaced by the original character.