A by director Vicente Silveira revealed that LinkedIn has not received any reports of unauthorised account access in the wake of the security breach.

The company also revealed that passwords of the service's users are now salted as well as hashed. "That transition was completed prior to news of the password theft breaking on Wednesday," Silveira wrote.

Ty Miller, chief technology officer of penetration testing firm Pure hacking, said that although the salting of password hashes has been around for a long time, "we find that many Web applications either do not hash their passwords at all, or use common hashing algorithms, such as MD5, without a salt".

"Social and professional networking sites such as LinkedIn are major targets for hackers," Miller said. "Combining this with the complexity of these types of web applications, the chance of a critical vulnerability being present is likely. This means that a defence-in-depth approach should be a necessity for LinkedIn, which includes protecting passwords with strong cryptographic methods."

Miller said that social networking services such as LinkedIn store a wealth of personal information about their users and have a responsibility to implement a very high standard of security, with security measures, such as salting password hashes, implemented as part of application design.