This question may be a basic question but it is not clear to me at the moment.
I have an Error Correcting Code (ECC) in a key-encapsulation scheme designed for post-quantum cryptography which operates on secret data.
The ECC I am using is constant time as long as the number of errors which need to be corrected is constant, and as long as those errors occur at the same positions in the message. The runtime does not depend on the secret data itself, only on the #errors and their positions in the secret data.
Does this leak any useful information? The # of errors which occur is not always constant in a real scenario...