The idea is that in typical assymetric cryptosystem you do some variant of bitwise exponentation of “large values” (ie. slow) and both the power envelope and ti

The idea is that in typical assymetric cryptosystem you do some variant of bitwise exponentation of “large values” (ie. slow) and both the power envelope and timing is directly related to individual bit values of the private key. This trivially works for RSA and also anything involving integer-like groups and then even for “classic” ECC, things like 25519 are intentionally designed to mitigate this kind of side channel.