# Tag Info

If I understand the question correctly, you are asking whether it's really needed to have the KEM be CCA secure, and maybe in the random oracle model it would suffice for it to just be an invertible one-way function. This would not be CCA2-secure. Specifically, let $f$ be any invertible one-way function, and construct $f'$ so that $f'(x)=0f(x)$ for every ...