WMJS LX BN HCBMSQF MHXTAJJ UO GJNOQXURDYF HRB UHH HJPKJS PUT (UM) VTGTZFSE ZTSKV
WMJS LX BN HCBMSQF MHXTAJJ UO GJNOQXURDYF HRB UHH HJPKJS PUT (UM) VTGTZFSE ZTSKV. decrypted reads:
THIS IS AN EXAMPLE MESSAGE TO DEMONSTRATE HOW THE CIPHER PRO (TM) SOFTWARE WORKS.
I found this by
Assuming it's a Vigenere cipher
and performing Kasiski's examination on the ciphertext. This tells us that the key is either 44, 22, 11, 4 or 2 characters long.If we assume 4 is the correct length, and then analyzing the letter frequency of each "row" (i.e. groups of letters that are 4 characters away from each other), we eventually arrive at the key
Edit: Turns out the only repeating substring has actually a distance of
44. So I basically found the solution by mistake :).
This of course is a very unsatisfying answer, and even with known plaintext & key I still don't know how to get the key from the image (assuming nothing else is hidden in the image!). I'll try again later, and maybe someone else figures it out faster with known key now.
By the way, "Cipher Pro (TM)" isn't a real software as far as I googled... Probably just a story-related fabricated name.
P.S.: Maybe another plaintext is hidden in the image? I somehow have the feeling the shown ciphertext isn't everything to solve...