I have a worksheet which contains a dozen ciphertexts where the goal is to decrypt the encrypted English sentence(s). No information is given about what the text contains or what cipher methods are used.
I've reach the last question but am stuck on them and have spent several hours stuck on trying to figure out which cipher was used. I've tried to run frequency analysis on them and trial and error'd some different keys for things like Caesar shifts, but was unsuccessful.
So basically, I don't know how to start approaching these problems. I'm unable to identify which cipher was used and what its key is. Could you please help me here?
- DGFMVXCRLCWMIDHDRLCHHDHVKLCAKYMAIHCAHEFIHZDRLHMUDRLFMVZSLIHLGGMZHLRLAHVCEEFFMVODEEMRLZYMQLFMVZDQQLKDCHLWZMSELQICAKGDAKFMVCZLZLCKFGMZUZLCHLZYXCEELAULI
Thank you in advance.
The first is a substitution:
{'a': 'n', 'c': 'a', 'b': 'k', 'e': 'l', 'd': 'i', 'g': 'f', 'f': 'y', 'i': 's', 'h': 't', 'k': 'd', 'j': 'j', 'm': 'o', 'l': 'e', 'o': 'w', 'n': 'q', 'q': 'm', 'p': 'x', 's': 'b', 'r': 'v', 'u': 'g', 't': 'z', 'w': 'p', 'v': 'u', 'y': 'c', 'x': 'h', 'z': 'r'}
the cleartext is
"if you have a positive attitude and constantly strive to give your best effort eventually you will overcome your immediate problems and find you are ready for greater challenges"
I ran the ciphertext against a genetic algorithm thing I threw together until the "if you have a positive attitude" bit jumped out at me, at which point getting the rest was pretty easy by hand. If you're interested in the code see https://github.com/frrad/cipher/blob/master/tools.py (it's really hacky)
edit: updated code can usually decrypt the message by itself
edit2: If you google "cryptogram solver" you can find other tools online like http://www.blisstonia.com/software/WebDecrypto/index.php