We use SHA512 instead of MD5 and SHA1.
*/
-bool prf(const char *secret, size_t secretlen, char *seed, size_t seedlen, char *out, size_t outlen) {
+bool prf(const char *secret, size_t secretlen, const char *seed, size_t seedlen, char *out, size_t outlen) {
assert(secret);
assert(secretlen);
assert(seed);