I'm about to implement my very first crypto system probably using AES128. (still trying to figure which mode to use)
Is there a weakness in encrypting a plain text of which 50% is known by the attacker? Will an attacker be able to decrypt the unknown 50%.
Let me explain. In my project I need to encrypt dictionaries (list of key/value). I suppose that all the keys are known to the attacker (by reverse engineering), as such an attacker knows more or less half of the plain text. Would that make the encryption of the values weaker?
For what I have understood of chosen plain text attacks, knowing a part of the plain text should not be a problem. But the approval of someone smarter than me would relieve me from anxiety.