Even the strongest algorithms may become weak in the hands of a human who does not understand the basic principles that underlie the tools/mechanisms he/she is working with. A good example is the LAN Manager (LM) hash, one of the first password hashing algorithms used by Windows operating systems, and the only version to be supported up until the advent of NTLM hashes used in Windows 2000, XP, Vista, and 7. Read about how the LM hashing worked and why it was weak by design at this link from techgneix: