file named "consolidated.db" that contained a record of iPhone users' locations. The file was added with the June 2010 iOS 4 update, though previous versions of iOS stored similar information in a file called "h-cells.plist". On April 20, 2011, The Guardian publicized research by Alasdair Allen and Pete Warden, who found that anyone with physical access to an iPhone could obtain a detailed record of its owner's location and movements over the past year. Moreover, the file was automatically backed up by iTunes onto any computer the iPhone was synchronized with. A Wall Street Journal investigation found that users' locations were still stored when location services are disabled. The controversy led to U.S. congressional scrutiny and an FCC investigation, and was dubbed "Locationgate" by the media. Apple responded on April 27, 2011, claiming that the data was used to cache nearby Wi-Fi hotspots and cell towers in order to improve location speed and accuracy. The company also claimed that locations being collected when location services were off, and being stored for more than a year, were both bugs. Apple issued an update for iOS (version 4.3.3, or 4.2.8 for the CDMA iPhone 4) which reduced the size of the cache, encrypted it, stopped it being backed up to iTunes, and erased it entirely whenever location services were turned off. Nevertheless, in July 2014, a report on state-owned China Central Television called iPhone tracking a "national security concern." Currently, iPhones contain a "Frequent Locations" database which records where users have been, along with exact times they arrived and left, raising concerns that the data could be used in court. This feature can be turned off. Child safety controversy In August 2021, Apple announced plans to scan iCloud Photos for child abuse imagery (through an algorithm called "NeuralHash"), and filter explicit images sent and received by children using iPhones (dubbed "Conversation Safety"), to be rolled out later that year. More than 90 policy and human rights groups wrote an open letter to condemn both features. Apple's plan to implement NeuralHash on-device rather than in the cloud led the EFF and security experts to call it a "backdoor" that could later be expanded to detect other types of contents, and would decrease users' privacy. Apple claimed the system was "misunderstood," but announced in December 2022 that the photo scanning feature would never be implemented. The other feature, Conversation Safety, was added in iOS