Skein_512_InitExt
(void) Skein_512_InitExt(ctx, sizeof (zio_cksum_t) * 8, 0,
int Skein_512_InitExt(Skein_512_Ctxt_t *ctx, size_t hashBitLen, u64b_t treeInfo, const u08b_t *key, size_t keyBytes);