The uniqueness of everyone’s voice can now be used to lock up data extra securely on mobile phones and portable computers, thanks to a prototype system developed by US researchers. The system could render stolen devices useless.

Existing voice identification systems rely on a person’s voiceprint alone before granting security clearance. A typed password can also be used, but this must be easy to remember and so may also easy to guess.

The new system goes further by combining the two. It combines a spoken password and the voiceprint of the speaker to generate a cryptographic key. This is then used to encrypt data automatically.