I read online that it's useless and basically impractical to hash a password with multiple hashing algorithms (and not just one) before storing them in a database. I don't really understand why that is. If someone gets their hands on a list of hashes and he doesn't know which hash functions were used, how can the passwords be cracked? It would seem that using a combination of multiple hash functions would make the passwords more secure... but apparently they don't. Why not?
I'm referring specifically to the section titled "Double Hashing & Wacky Hash Functions" in this blog post.