1. Monoalphabetic Substitution Cipher:

The ciphertext below was encrypted using a substitution cipher. Decrypt it without knowledge of the key.

dct hivynd vx xvvg xvf thrc kltratk vx rvyfkt eawtk dct tzdftit paiad dv mcarc thrc rhn anrfthkt byd wtfj xftsytndpj ad ak nvd dct vbdhanane xvvg byd dct ktfwane hk lftj dv vdctf hnaihpk mcarc gtdtfiantk dct hwtfhet nyibtfk vx h kltratk dcyk dctft kttik dv bt paddpt gvybd dchd dct kdvrq vx lhfdfagetk efvykt hng chftk vn hnj phfet tkdhdt gtltngk rcatxpj vn dct gtkdfyrdavn vx wtfian ax nvd vnt cthg vx ehit mtft kcvd gyfane dct ntzd dmtndj jthfk an tnephng hng hd dct khit dait ax nv wtfian mtft gtkdfvjtg dctft mvypg an hpp lfvbhbapadj bt ptkk ehit dchn hd lftktnd hpdcvyec cyngftgk vx dcvykhngk vx ehit hnaihpk hft nvm hnnyhppj qapptg vn dct vdctf chng an kvit rhktk hk madc dct tptlchnd hng fcanvrtfvk nvnt hft gtkdfvjtg bj bthkdk vx lftj twtn dct daetf an angah ivkd fhftpj ghftk dv hddhrq h jvyne tptlchnd lfvdtrdtg bj adk ghi

1. 1. Compute the relative frequency of all letters A..Z in the ciphertext. You may want to use a tool such as the open-source program CrypTool for this task. However, a paper and pencil approach is still doable.
   2. Decrypt the ciphertext with the help of the relative letter frequency (and word frequency, doubled letter frequency, etc) of English. Note that the text is relatively short and that the letter frequencies in it might not perfectly align with that of general English from the table.
   3. Who wrote it?
2. Vigenre's (well, della Porta's) Cipher:

The following has been enciphered with Vigenre's (well, della Porta's) cipher. The alphabets were left in-order (e.g. ABCDEF...). The password is a 4 letter word in English. (It is not a naughty word!) Note: Ignore the spaces.

look enqq xuvc rtku mlde itlf msoc aidj jifb sulg hofm xwsl xilr sbwr sozy vdts xngr xogc esqy psgu ildg whgs pdyg zelf imsl mcwj snyk isky kexm vtzc qtgy tpdw wtsr mslg gslm mhst itgi iehr cpal ktge mvwr leeq smwr life

2. 1. Apply either the Kasiski or Friedman test. (Just one, not both.) How long does the test say the password is?
   2. Decrypt the ciphertext. (It is not hard: my automated program did it just knowing that the password was 4 letters, and that the most common letters in English are ETAOINS.)
   3. What was the password?
3. Rectangular Transposition Cipher:

The following 80 letters have been enciphered with a rectangular transposition cipher. Note: Ignore the spaces.

izig rheo oiot nosp hbds eaye uyti nbot tosu rsut naeg ionl htws fnur piet eosi iasn toli ohni ttet

3. 1. Decipher it.
   2. How many columns were used?
4. Comparison:

Mono-alphabetic substitution ciphers leave the letter frequencies the same as in the plain text language, even if they change what the letters are. Transposition cipherspurposefully leave the letter frequencies the same. Please describe two ways that, by looking at the ciphertext only, one might guess if that text had been enciphered with aMono-alphabetic substitution cipher or a Transposition cipher.