Directions: Encrypt the following plain text.
Sample key is displayed
in the box below. It should
be a permutation of the sequence
ABCDEFGHIJKLMNOPQRSTUVWXYZ. Thus,
if the key is EUCLIDABFGHJKMNOPQRSTVWXYZ,
then a is mapped to A, b to U, etc.
Note: Even though this encryption scheme
has a large number of keys, it can be broken
by frequency analysis if a paragraph or so of ciphertext
is available. The earliest known reference to
frequency analysis is in "A Manuscript on
Deciphering Cryptographic Messages," by
al-Kindi. Al-Kindi's treatise was written in the ninth century
but was subsequently lost, to be rediscovered in 1987 in an archive in
Istanbul. See Simon Singh's "The Code Book."