1) Encipher VERMONT using a one-time pad with random shifts 9, 11, 3, 20, 7, 15, 10.

2) Encipher WHERE IS THE SUN using a Vigenere cipher with keyword BED.

3) The message IDMKPHSIJMHVD was enciphered using a Vigenere cipher with keyword JORDAN. Decipher the message.

4) An intercepted message has the following frequency distribution :
 

		A	B	C	D	E	F	G	H	I	R
		41	101	68	93	67	134	95	122	133	68
		J	K	L	M	N	O	P	Q	R
		125	76	85	199	120	87	59	59	68
		S	T	U	V	W	X	Y	Z
		107	113	81	82	85	147	113	101

Explain why it might be reasonable to conclude that (a) it was not enciphered using a monoalpahbetic substitution and (b) it might have been enciphered using a Vigenere cipher.

A cryptanalyst decided to proceed on the assumption that it was a Vigenere cipher. The table below shows 4 different character strings each of which appeared at least twice in the enciphered message. The first two strings appeared three times. The table shows the location within the message (number of characters from the start) of each occurrence of the strings.
 

	String	Location 1	Location 2	Location 3
	DXKEFK	477	750	1632
	NLVBDF	1255	1934	2375
	KFEITSCINTR	309	1814
	UTPFRNDSBEO	345	1395

(c) What is the most likely length of the keyword?

(d) What would be the next step in the attempt to "crack" this message?

5) The Playfair Cipher: In 1854, Sir Charles Wheatstone invented the cipher known as "Playfair." It was used by the British in the Boer War and the First World War, and by several armed forces in the Second World War. When (future U.S. President) Lt. John F. Kennedy's PT-109 was sunk by a Japanese cruiser in the Solomon Islands, he made it to shore on an enemy island and was able to send an emergency message in Playfair to arrange the rescue of the survivors from his crew. For more of the history of the Playfair Cipher and a description of how to use it, see http://www.math.temple.edu/~renault/cryptology/playfair.html

(a) Use the Playfair cipher with keyword TURING to encipher the phrase BREAKING THE CODE.

(b) The following message was enciphered with a Playfair cipher using the keyword CIPHER. Decipher it: RVNHNHHUNHDQQUUHBORGPZINUQKEMCSY