The following ciphertext was made with a substitution cipher. Decrypt as much of

Question

The following ciphertext was made with a substitution cipher. Decrypt as much of the ciphertext as you can. Then give as much information as you can about the encryption as you can about the encryption key. (that is, the permutation of the alphabet used to make the ciphertext). Hint: Letter "e" is not the most common letter in the orginial message

FYNJS AJYFV SPJSQ FBKSK FSBQA SNPEA SDDCV SBYVE JBFVC HJRGA XGFDD CVVSP KCBJ

I was wondering if someone could help me because I am not sure what to do

Explanation / Answer

substitution cipher::

A simple substitution cipher is a method of concealment that replaces each letter of a plaintext message with another letter.

Here is the key to a simple substitution cipher:

Plaintext letters: abcdefghijklmnopqrstuvwxyz

Ciphertext letters: EKMFLGDQVZNTOWYHXUSPAIBRCJ

The key gives the correspondence between a plaintext letter and its replacement ciphertext letter. (It is traditional to use small letters for plaintext and capital letters, or small capital letters, for ciphertext. We will not use small capital letters for ciphertext so that plaintext and ciphertext letters will line up vertically.) Using this key, every plaintext letter a would be replaced by ciphertext E, every plaintext letter e by L, etc. The plaintext

message simple substitution cipher would become SVOHTL SAKSPVPAPVYW MVHQLU.

The key above was generated by randomly drawing slips of paper with letters of the alphabet written on them from a bag that had been thoroughly shaken to mix up the slips. The first letter drawn E became the substitution for a, the second letter drawn K became the substitution for b, etc.

Encryption (or enciphering) is the process of using the key to produce ciphertext from plaintext. Decryption (or deciphering) is the process of using the key to produce plaintext from ciphertext.

To encrypt a message requires knowing two things: the method of encryption (in our case, simple substitution) and the key (in our case, the letter substitutions). Notice that if we believed that our messages were no longer secure, we could leave the method unchanged (simple substitution) but change the key (use different letter substitutions).

Here is a message to decrypt. It has been encrypted with a simple substitution cipher with key:

Plaintext letters: abcdefghijklmnopqrstuvwxyz

Ciphertext letters: HUFRCOGMTZXLKPNWYVABQSIEDJ BMC XTP MHBM PNBC NO HLL BMHB BMCD TPBCPR, UD TPBCVFCBTNP IMTFM BMCD RVCHK PNB NO.

Decrypt the message. Knowing the key, this should not be a problem. Although it might be useful to have the ciphertext letters in alphabetical order for decryption, the key is the same for encryption and decryption.

Plaintext letters: steyxdgawzmlhofnudvibrpkqj

Ciphertext letters: ABCDEFGHIJKLMNOPQRSTUVWXYZ

But, how would a person solve the message not knowing the key? Solving the message not knowing the key is called cryptanalysis. Cryptanalysts take up the “implied challenged to the ingenuity” that is tossed down by secret writing, and they find, when successful, satisfaction of their “not uncommon desire to discover a secret.”

FYNJS AJYFV SPJSQ FBKSK FSBQA SNPEA SDDCV SBYVE JBFVC

tlwae nalto edaem tirer teimn ewdun eppso eilou aitos

HJRGA XGFDD CVVSP KCBJ

faycn gctpp sooed rsia

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