Most current cryptographic hash functions have no lookup tables, multiplies, or other data dependencies and are constant time even when used with a secret key a

Most current cryptographic hash functions have no lookup tables, multiplies, or other data dependencies and are constant time even when used with a secret key as in HMAC. Obviously variable input length varies run time as with all symmetric crypto. See the end of this long Stack Exchange answer by a well-regarded cryptography implementer: https://crypto.stackexchange.com/a/11305/8925 https://crypto.stackexchange.com/a/11305/8925