In a project that I'm currently working on, we are encrypting some data using AES with ECB mode in a database. Each piece of data being encrypted is very small, no more than 10 characters long.
Very importantly, each entry of that database is encrypted using a different and unique key. Would we gain any security if we switched to AES with CBC mode in this specific scenario?
Also, imagine now that we use AES in ECB mode to encrypt the data in the database, but we now use the same key to encrypt every single entry. If an attacker breaks into our database and steals our data, how many entries would he need to exploit ECB weaknesses and be able to decrypt the information?
For this last scenario, I guess that what I want to find out is if an attacker can decrypt some AES ECB encrypted data if he only has, let's say, around 10 encrypted messages.