Homework, due January 14

1) Read Chapter 2 of Singh. Describe homophonic ciphers and syllable ciphers. Explain why these are more secure than monoalphabetic ciphers.

2) Encipher the following plaintexts using the given keywords.

a) LOVE YOUR NEIGHBOR YET PULL NOT DOWN YOUR HEDGE, keyword GEORGE (George Herbert, Jacula Prudentum)

3) Decipher the following ciphertexts using the indicated keywords.

a) NEKAV MNWJG JBJOA OZXYX RRGRG WRRZN TWIIJ TDEGK JRXBE DVIGI IXETJ RSHJ, keyword Bertrand. (Bertrand Russell)

b) MYMRR ODRHG BHRXC SRRTP NZSAA ZKHYK LHLKW GRUXI MIG, keyword Triangle. (Euclid)

4) Determine the 8-letter keywords that will decipher XPBOANYT as the given plaintext.

a) ISITOVER

b) HEADWEST

c) TROUBLES

d) HEISFREE

5) Suppose you know the ciphertext

EZZXP LEIMH WIYLZ KVBXH KJUE

To be an encipherment of

LIFEI SNOTA DRESS REHEA RSAL.

(Rose Tremain)

Assuming that

UVUNA RZMHU EPNAL IIIFP LVIYO TGJBU XJM (Stendhal)

Is enciphered by the same keyword, find the original message.

(Problems 2-5 are from Thomas Barr's Introduction to Cryptology book.)