“Padding is invalid and cannot be removed” using AesManaged

Question

I\'m trying to get simple encryption/decryption working with AesManaged, but I keep getting an exception when trying to close the decryption stream. The string here gets en

Answer 1

This exception can be caused by a mismatch of any one of a number of encryption parameters.

I used the Security.Cryptography.Debug interface to trace all parameters used in the encrypt/decrypt methods.

Finally I found out that my problem was that I set the KeySize property after setting the Key causing the class to regenerate a random key and not using the key that I was initially set up.