i wondered what the security implications are if I do the following. If I had a large file encrypted with a OTP and want to change only a few bytes in the plaintext. what security vulnerabilities do I get if I only generate a new OTP for the changing bytes leave the old OTP as is and substitute the new OTP, and do this every time i make a change to the plaintext.
To be clear:
- plaintext p;
- OTP o;
- cyphertext c
p = 1111 1111 1111 1111 o = 0001 0001 0001 0001 c = 1110 1110 1110 1110
p = 1111 1111 1111 __1010__
generate new OTP for the last 4 bit 0101 und substitute it in the "old" OTP…
o = 0001 0001 0001 __0101__ c = 1110 1110 1110 1111
What are the problems ( if there are any ) resulting from this?
I know that if I want to use OTP, I have to generate a hole new pad. But if I have a huge file (multiple GBs), it is hard to generate a new pad of this size if I only want to change a few bytes.
I haven't found material about this topic so far and analyzing attacks against some cypher application is a hard task, but maybe someone has read an article about that OTP application and why you should not do this.