http://www.corecipher.com/ciphertext/
Suppose you knew a message had been coded using a Substitution Cipher. Substitution Cipher is defined below?
THIS QUESTION COULD BE BASED ON PERMUTATION OR COMBINATION. Suppose you knew a message had been coded using a Substitution cipher. If it took you one second to try out each key, how many days would it take for you to try all possible keys on this message? Definition of SUBSTITUTION CIPHER from WIKIPEDIA:In Cryptography, a substitution cipher is a method of Encryption by which units of plaintext are substituted with ciphertext according to a regular system; the “units” may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth. The receiver deciphers the text by performing an inverse substitution.
Without the key or any guidelines, a human would never be able to crack a substitution cipher.
You wouldn’t know if the letter A was substituted with a number (like 7), a small group of letters (oGq), or a large group of letters and/or numbers (tU3EWdf98bvsw1dgJJ).
How To Send Secret Messages