I have a couple of questions pertaining to a RSA problem. I need to decipher some ciphertext and find out what the original plaintext was.
Modulus: $n = 2537$ and exponent: $a = 11$
Encrypting function: $E(x) = x^{11} \mod 2537$
Using Fermat's Little Theorem to start, I have successfully encrypted some plaintext and decrypted it, so I do know what the other required numbers in this particular RSA system are, however if initially I am only given $n$ and $a$ can I:
Mathematically work out some plaintext, if the ciphertext, $n$, and $a$ are known? If so would I basically step through the encryption process in reverse?
If not, what is the best/most effective cryptanalysis method to work out what the original plaintext is, if $n$ is relatively small (2537) and $a$ is relatively small (11)?
Note: This is needs to be calculated using the 'maths' behind the system and not a specific computer function.