Security researchers have released a tool that allows victims of the infamous CryptoLocker ransomware to unlock their computers at no charge.

DecryptoLocker from net security firm FireEye and threat intelligence company FoxIT offers a cure for the estimated 500,000 victims of CryptoLocker.

Victims need to upload a CryptoLocker-encrypted file onto the DecryptCryptoLocker portal in order to get the private keys necessary to decrypt files, as explained in a blog post by FireEye.

A FireEye spokesman told El Reg that a cache of private keys obtained from a commandeered command and control server was used to develop the decryption utility. That means CryptoLocker's encryption scheme remains unbroken, which, since it is based on best practices in cryptography otherwise used to protect e-commerce and privacy more generally, is actually a good thing.