XOR reversibility operation task

Question

I heard somewhere that using XOR is not reversible (they talked about encryption), but I don’t understand how it was intended? AFAIK, even with the OR operation, you cannot find out which of the two bits was 1. Please, could someone who knows how this was intended explain it to me? Thanks you

Answer 1

I think you probably quoted them incorrectly.

They probably meant that using a one-time pane is unbreakable, because if you don't have a copy of one time pad, there is absolutely no information in the ciphertext that you can use to recover plain text. You cannot use statistical analysis or even brute force search, because all the inputs can give a result with equal probability, and there is no way to find out which input is correct.

Disposable gaskets are usually implemented using XOR, but the irreversibility is that it is a disposable panel, and not because of the XOR operation.

Answer 2

if you do

z = x XOR y

then

x = z XOR y

so yes its reversible

Answer 3

You probably mean " XOR encryption is unbreakable without a key"

If the key is random and as long as the message (so it never repeats), the XOR cipher is more secure. A keystream generates a pseudo random number generator, the result is a stream cipher. With the key, this is a truly random result, a one-time panel that is unbreakable even in theory.

Answer 4

They probably meant that XOR is reversible, unlike AND or OR. For encryption, this is interesting primarily for Vernam ciphers - those where your cipher creates the key stream that you XOR with the data stream. On the receiving side, you can XOR an encrypted stream with the same key stream and return the text back.

It is also interesting in terms of cryptanalysis. For example, if two streams were encrypted with the same key stream, XORing them with each other gives you the XOR of two plaintext streams, and all the effects of the key stream are deleted. At this stage, you can use the "sliding window" technique: XOR, in your opinion, can be in one message at different points with this stream, and if it is there, the result will be an understandable text of another message.