Lawyers for Szpyrka could not immediately be reached for comment.

LinkedIn stored passwords in "hashed," or encrypted format, but did not "salt" them as many websites do, meaning it did not add additional random characters to make the encryption more difficult to break. After being posted in their hashed format, some of the passwords were decrypted. LinkedIn has salting passwords.

According to the lawsuit, LinkedIn also relied on an outmoded hashing format to store passwords and did not adhere to "basic security checklists" supplied by the U.S. National Institute of Standards and Technology to prevent the type of attack, called a SQL injection attack, that allowed hackers to gain access.

The IDG News Service