A 38-year-old charity will be integrated into Apple’s newest operating system – The Economist

Aug 12th 2021

THE NATIONAL Centre for Missing & Exploited Children was established through an act of Congress in 1983, but it is not part of the American government. NCMEC (pronounced nic-mic) is a charity, one funded almost entirely by the Department of Justice, and which operates as a clearing house for information about abducted children. For the first few decades of its existence NCMECs focus was on abductions in America, helping investigations run across state lines. But as the use of the internet grew it started to turn its attention to the harm caused through online activity, specifically the trade of imagery depicting the sexual abuse of children.

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NCMECs role as an information clearing house has become far more technical as a result. In 1998 it started building a database of imagery known to depict sexual abuse of children based on the tips it had received. The technical term for this kind of data is CSAM (Child Sexual Abuse Material), mostly images or videos. Only NCMEC is shielded from liability to the extent that it can store CSAM and share it with law enforcement, but in 2006 the organisation began to think of ways that it might use the database to catch other CSAM trafficking. It came up with the idea of generating a long, unique string of letters and numbers known as a hash for each image in its database, then sharing those hashes with companies that wanted to scan their services for CSAM. By reversing the hashing process, companies could scan images on their services just for known CSAM, and report anything they found back to NCMEC.

This has led to an expansion of the number of tips that are sent to NCMEC, as technology companies scan automatically and voluntarily for CSAM. In 2010 NCMEC received 220,000 tips. By 2020 that number had grown to 21.7 million. And it is set to get bigger. On August 5th Apple announced that the next generation of its phone and laptop software would come with NCMECs hash database pre-installed, and would scan its users devices for CSAM automatically. Apples plans have stimulated fierce debate about whether the new system will provide an avenue for governments to expand their capacity to scan private devices for other illicit content. Many technology companies already used NCMECs hashes to scan their own cloud servers for CSAM, but Apple is taking this further with an encrypted system that runs scans on users own phones and laptops.

Yet the government could not easily force NCMEC or Apple to tweak this phone-scanning capability to look for other things. That is because any evidence thrown up by those compelled searches would be inadmissible in court for violating the Fourth Amendment. Crucially, none of the technology companies scanning for CSAM, nor NCMECs storage of it, does so, because the scans are done on a voluntary basis. The Fourth Amendment only protects against unreasonable searches by the governmentones that are carried out without a warrant. Arrests can be made only because of the voluntary nature of the CSAM scanning.

Most of the attention has focused on the technical details of Apples new CSAM scanning system. It will be released along with iOS15, the next update to its iPhone operating system, in September. Those technical details are important. Experts are poring over every available detail of the new software to determine whether it has introduced a security weakness to iPhones. But Apples ability to make this change also rests on the social norms that have underpinned the fight against child abuse in America for decades. The willing co-operation of third parties has long been all that makes it possible for law enforcement to track down child abusers in private spaces. Apple is now testing whether this willingness extends into the phones in Americans pockets.

This article appeared in the United States section of the print edition under the headline "Hashing ambiguous"

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A 38-year-old charity will be integrated into Apple's newest operating system - The Economist