use crate::;
// TODO: Should we just switch to truncated SHA512?
// https://bitcoin.stackexchange.com/questions/8443/where-is-double-hashing-performed-in-bitcoin
/*
To avoid this property, Ferguson and Schneier suggested using SHA256d = SHA256(SHA256(x))
which avoids length-extension attacks. This construction has some minor weaknesses
(not relevant to bitcoin), so I wouldn't recommend it for new protocols,
and would use HMAC with constant key, or truncated SHA512 instead.
*/