London Telegraph 
July 30, 2013
A string of code from iOS 7 revealing ‘a fingerprint that changes colour during the setup process’ was posted online yesterday, sparking rumours that the new iPhone could contain a fingerprint sensor.
If the rumours are true, the latest iPhone will be the first Apple product to feature such a sensor, which could be used for unlocking the homescreen or confirming identity for payment from the App Store or other outlets. Any sensor would likely be embedded into the physical home button.
Earlier this year it was reported that a supply chain source in Taiwan said Apple had been forced to delay production of the next iPhone due to failure to find a coating material that did not interfere with the fingerprint sensor.