I figured that a really secure password would be an AES 128 key. If this key were to be base 64 encoded, I could replace 4 random bytes in it in order to make it unusable unless you know which bytes were replaced and by what.
The process would be like this:
- generate a key:
- base64 encode it to make it readable:
- replace 4 random bytes of it
- I would remember what the 4 bytes are i.e. the password
- the computer would remember which bytes got changed (in this case: 13, 6, 19, 15) and in what order
My question is: how difficult (how many attempts) would it be to guess the correct key if you got hold of the original.
Another way of asking this is: how long has the key to be in order to make it difficult (several decades of guessing with a super computer) with changing just 4 random bytes.
I guess there is a simple mathematical formula to calculate this. But I don't know it.
thank you for your support