Another thing that I was thinking about is limiting the keyspace:
If we suppose that each plaintext is more likely to contain each char (that it is composed of) only 1 or 2 times and we had an algorithm that checks these keys of plaintext first that could save a lot of time.
e.g. take a look at these plaintexts:
Code: Select all
A plaintext eighter has a limited charset (because of double chars) or it has limited double chars.
So you will need two attack types:
1. check with small charsets (especially frequent chars, such as vowels and "123")
2. if the key allready contains two instances of "A", eleminate "A" from the charset in use. the rest is brute force