^\S*(?=\S{8,})(?=\S*[a-z])(?=\S*[A-Z])(?=\S*[\d])\S*$
From the fine folks over at Zorched.
^: anchored to beginning of string\S*: any set of characters(?=\S{8,}): of at least length 8(?=\S*[a-z]): containing at least one lowercase letter(?=\S*[A-Z]): and at least one uppercase letter(?=\S*[\d]): and at least one number$: anchored to the end of the string
To include special characters, just add (?=\S*[\W]), which is non-word characters.
