PhotoDNA Lets Google, FB and Others Hunt Down Child Pornography Without Looking at Your Photos


Earlier this week it came out that Google turned over a man whose emails had contained an unstated amount of child pornography. And while the world as a whole seemed glad to have the perpetrator caught, there was some concern as to how whether Google dug through his emails to find these images, effectively killing the privacy of email.

However, it’s through a dedicated software that uses unique hashtags of sorts that drew Google to outing this individual. It’s called PhotoDNA and is developed by none other than Microsoft.


Working closely with the National Center for Missing and Exploited Children’s Cybertipline Child Victim Identification Program, Google, Facebook, Twitter, Bing, OneDrive and a number of other high profile sites use PhotoDNA to track down illicit photos. Using a database of known images, PhotoDNA runs only the metadata of images through for comparison, without ever actually touching someone’s inbox.

As described in a blogpost from Google,

Since 2008, we’ve used “hashing” technology to tag known child sexual abuse images, allowing us to identify duplicate images which may exist elsewhere. Each offending image in effect gets a unique ID that our computers can recognize without humans having to view them again. Recently, we’ve started working to incorporate encrypted “fingerprints” of child sexual abuse images into a cross-industry database. This will enable companies, law enforcement and charities to better collaborate on detecting and removing these images, and to take action against the criminals.

As mentioned above, Google isn’t the only service utilizing PhotoDNA. After reports of Google using the service came out, Facebook also confirmed that it keeps a lookout for sexually exploitive photos of children. In speaking with SlashGear, a Facebook spokesperson said, “There is no place for child exploitative content on Facebook. We use PhotoDNA to check that each image which is uploaded to our site is not a known child abuse image.”

This sort of technology is used far beyond just the scope of child exploitation, as it’s almost identical to the method Dropbox uses to detect when there’s copyrighted content being shared across its servers. However, Google has stated that they only use this technology to track cases of child sexual abuse.

So, while we were most definitely relieved to see the offender tracked down and turned over, we can now also rest assured that Google isn’t systematically going through our inboxes, searching through our private images.

(via PopPhoto)

  • CJ Jacobs

    I was shouted down in a post, slamming Google, trying to explain to people that Google wasn’t looking at the actual pictures but tracking known child porn via photo recognition software. Glad to see articles like this make that fact clear.

  • Jonathan Maniago

    “However, Google has stated that they only use this technology to track cases of child sexual abuse.”

    That leaves me wondering why this was limited specifically to child sexual abuse. Nothing else out there deserves special treatment?

  • Josh Zytkiewicz

    What else would you use it for?

    I can’t think of any other images that are illegal to posses under all circumstances in almost every single jurisdiction.

  • Thekaph


  • Jonathan Maniago

    Well, abuse doesn’t always have to involve sex or children. Besides that, maybe the usual security issues? Airports, government/military buildings, etc.

    Not that I want them to go for it; I’m just curious about their criteria.

  • Josh Zytkiewicz

    Not illegal. Images showing a murder have won the Pulitzer Prize.

  • Gannon Burgett

    My guess is most other material is transferred through text, not images, meaning this software would be irrelevant.

  • Thekaph

    Well I should have been more explicit: “A snuff film is a motion picture genre that depicts the actual murder of a person or people, without the aid of special effects, for the express purpose of distribution and entertainment or financial exploitation.”.

    When the murder is committed for the purpose of the picture the photography is illegal, isn’t it?

    (this is a real question though, I am not being sarcastical).

    EDIT: It is possession though. What about production? Could such software be use to locate the content provider (if I may use this expression)?

  • Josh Zytkiewicz

    Possessing images of a crime, or of something people disapprove of, or even “secure” areas is not illegal most of the time.

    Using a program like this on those kind of images would create too many false positives.

  • hansmast

    Great! Now with this publicity, child pornographers know they just need to strip the metadata to be safe. Hopefully it will soon be upgraded to also do a one-way hash of the actual image data with pattern recognition to recognize even down-sized and JPEG compressed images.

  • Burnin Biomass

    Been that way for awhile. For years photolabs usually had rules about reporting any child pornography, but nothing specific about other criminal acts.

  • Jason Yuen

    Google also uses this technology on youtube videos. Most notably on the audio of the video you upload. If it finds a match to copyrighted content (ie. music/songs), then it immediately notifies you. It’s not new technology.

  • Chang

    This would probably be contested as “free speech” by the Islamist-militant loving, freedom hating usual suspects in Western law circles. Not that other people don’t make snuff films, it’s just those are the ones you’re likely to find on LiveLeak or Ogrish.

  • Gannon Burgett

    The hashes that are scanned are unable to be removed.

  • hansmast

    The article says, “PhotoDNA runs only the metadata of images through for comparison, without ever actually touching someone’s inbox.”

    Metadata can be easily stripped from the photo before it is emailed, thus easily circumventing the software.

  • hansmast

    The tech Google uses is actually much more advanced than this. According to PetaPixel all that PhotoDNA does is “runs only the metadata of images through for comparison” while the Google tech actually does an analysis of the audio content to create a fingerprint/pattern recognition hash.

  • Matt

    Sorry, but e-mail is NOT private. You have to encrypt it inorder to be private. Otherwise, it is available to the public and there is a trail (and copies) of it going from email syste to email system. Kind of like sending a physical post card through the regular postal service, anyone could read it along the way. Of course, the chance of someone wanting to read your email is really low.
    Sure, the big companies say they respect your privacy. But, the reality is it is up to you to ensure your own privacy. Do I encrypt? No, no need, I realy do not care if someone reads my emails. I do not put anything in email that I would not say in public, because it kind of is public.

  • Biff

    Sounds about right:

    Those conservative religious Imams would contest this.

    So would the conservative Taliban.

    As would those conservative Islamic religious extremists.

    The Southern, conservative, bigots in the KluKluxKlan would fight to preserve their freedom to spew hate-speech.

    All these conservatives would be muzzled into silence if not for those pinko, commie liberals defending everyone’s freedom of speech.

    Those freedom-hating liberals should just pipedown and allow us to gag hate-mongers such as those conservative, Republican Neo-Nazi groups & the Southern Republican KKK.

    And after we gag these hate-groups: we can start gagging everyone who disagrees with us.

    In the name of “freedom.”

  • Chang

    I have no idea what you are supporting. Are you then a fan of child pornography as free speech? Because one could argue it is somewhat less damaging to a person than being the star of a snuff film.

    Freedom has some limits in civil society.

  • Biff

    I noticed you addressed child porn, but had nothing to say about your conservative “Islamist” brethren & the KKK.

    I have no problem with limits on child porn.

    But it seems you got problems with those supposed “Islamist-lovin” liberals.

    So I wanted to see if you realized that those religious fundamentalist extremists belong on the right wing of the political spectrum.

    They are conservatives.

    Just like their conservative Neo-Nazi counterparts and the KKK.

    The sooner you know where groups belong in the political spectrum, the sooner you can start loving your brothers in Islam and the KKK.

  • Chang

    There are at least three problems with your post. One, an intellectually sloppy conflation of medieval, murderous religious fundamentalism and “conservatism” (whatever you mean by that.) There is nothing in Salafist Islamic law remotely resembling Austrian economics, freedom of conscience, or freedom of speech. They are actually much more into state/church control of everything, making them more Wilson Democrats than anything right-wing.

    Two, the similar mischaracterization of racism as a “conservative” trait. Remember Senator Rebecca Felton ( a Democrat) was an outspoken proponent of women’s suffrage, school and prison reform, and the lynching of black men. Real Nazis were proponents of nationalized industry, national health care, and a strong welfare state (hence the “Socialist” part many progressives like to ignore) on top of being racists. Racism is a plague on both left and right political extremes, and it is intellectually dishonest of you to purport otherwise.

    And three, you make the unfounded supposition that because I oppose the defense of terrorists’ “free speech” rights in posting snuff films on the internet, that I somehow have something deeply in common with them. Reasonable limits to the exercise of rights have been debated since Rousseau, at least, and probably before though not in a modern context. Arguing a snuff film isn’t one hardly makes a person into cross-burning zealot.

    The sooner you learn to honestly engage with others, and attempt to reason without blanket presuppositions about their intent or beliefs outside those directly at hand, the sooner you will be a productive citizen.

  • Biff

    > “hence the “Socialist” part many progressives like to ignore”

    You lost your credibility there.

    You don’t suddenly make Nazis into liberals just because of “nationalization.”

    “First they came for the Socialists, and I did not speak out—
    Because I was not a Socialist.
    Then they came for Trade Unionists, and I did not speak out—
    Because I was not a Trade Unionist..”

    Ask yourself why Nazis targeted the same groups targeted by Republicans today.

    “You only need to look at who supported Hitler, Mussolini, and Franco to get an idea of whether they were Right or Left.

    Franco drew his support from the military, the Catholic Church, the religious, and well-off landowners. He opposed secularist forces, trade unions, and socialist parties.

    Mussolini got support from patriots/nationalists, his primary financial backing came from armaments firms, and the party that most consistently partnered with him was the pro-Church Italian People’s Party.

    And the Nazi’s Enabling Act was strongly opposed by the left-wing Social Democrats and Communists and supported by the Catholic Center Party and the conservative German National People’s Party (the party of the junkers and wealthy industrialists).

    If you look at the areas that the Nazis were strong in during the Weimer Republic, those areas in the present day support parties broadly acknowledged as conservative or right wing. Nazis/fascists, of course, were always the most anti-Communist of all the parties and explicitly believed in using government policy to re-enforce traditional gender roles.

    The proof’s in the pudding, as they say. Look at who opposed the Nazis and by and large they were the Left; look at who supported them, and they were by and large the Right. If you want to say Nazis and fascists weren’t right-wing, then you at least have to concede that right-wingers and conservatives saw them as supporting their interests.”-Zephyurs

  • Biff

    I grew up supremely ultra-conservative with a highly militaristic world-view.

    And even in those circles, we pegged the Nazis as conservative.

    Hell, after the war: the German nation themselves pegged the Nazis as conservatives.

    European consensus is that they were conservative. Even by their own conservatives.

    Which is why it blows European minds when they hear that there are Americans who think Nazis were liberal.

    When you think Socially Conservative, you think of Burkas, conservative clothing, uniforms, religion, tradition, Patriarchy, obedience, restrictions, exclusiveness, xenophobia, anti-immigration.

    When you think of Socially Liberal, you think openness, acceptance, tolerance, anarchy, rebellion.

    Now which one fits the Nazis.

  • Lance Mitaro

    Kennedy’s brains explode!

  • Tiglath Philizar

    Anybody ever wonder why there are so many child porn(CP) busts? Anyone?
    Other than, ” perv” comments NO one seems to ask Why? How? Where? instead people focus on the words “CP” and allow their angst and antipathy to do the rest. The entertainment industry has a CP database (THORN). So called Vigilantes(perverted justice), GOOGLE, NCMEC, the FBI and ICE as well have them as well. They use CP hash tags to embedd (steganography) into the content some P2P downloads. These embedded hash-tags are picked up by law enforcement software who record the IP address and the rest is HELL for whom the bell tolls. With current CP laws much can be considered CP even clothed children and after the police arrive at your door, and they will something on your computer could be considered CP even a SEARCH TERM. .

    During the fight to pass the infamous “$700 Billion BANK Bailout” plan (a.k.a. HR 1424), Congress added $300 million to finance the current CHILD PORN WITCH HUNT. Spending money this nation doesn’t have only for it to be paid back by our children’s children now that is Child Abuse.Our nation is running on BORROWED money while thousands are going to jail for VICTIM-LESS crimes on the nations credit card around $35,000/yr/inmate. People in jail who downloaded CP intentionally or not, THOUSANDS. 24 per day, 168 per week, 672 per month, over 8000 per year and those numbers are on the low end.

    In 2004 the FBI launched along with a myriad of other law enforcement personnel Operation Peer Pressure. They conducted 166 undercover on-line sessions using P2P networks in which FBI Agents download CP from offender’s computers. The FBI states that operation netted over 300 search warrants to be executed; out of those 300 warrants 69 subjects were indicted and 63 subjects were arrested, and over 40 convictions were achieved. Let us break that down. Out of the 166 on line searches 300 search warrants were issued there by destroying 300 lives including the lives of the people in those homes searched. Out of those 300 only 69 were indicted and 231 were not. The newspapers only reported their arrests and are complicit in destroying their lives as well. Only 63 were arrested out of the 300 and 40 convictions achieved. So the FBI believes it is OK to destroy 260 peoples lives to convict 40 people for doing nothing more than look at pictures. You never hear that in newscasts DO YOU? People are committing suicide over this only to find they were abused themselves. Why is it those that have the loudest bark have the biggest problem?

    Think logically for just one minute. If front of me I have a voodoo doll I stick that voodoo doll with a pin and the person I curse is injured. CP Voodoo logic; Someone possesses a photo of a child, in the form of 0′s and 1′s in a computer file. When s/he looks at the medium, the individual depicted in the photo, video or both gets victimized and hurt. While I can appreciate that actual creating CP victimizes children, I cannot agree that looking for, viewing, or collecting CP actually victimizes anyone. If you were to apply the same reasoning to any other crime, then looking at a photo of any crime would be re-victimizing someone.

    Use that same voodoo logic and the same reasoning law enforcement uses and apply it to murder and terrorism. If anyone looks for, views images or video footage of 9/11, nazi war crimes, or autopsy photos, etc, they would be guilty of having re-victimized people viewed in that medium being a photo, video or both. Where was the child abuse industry when the bombs were killing thousands of children in Iraq and Afghanistan; now that my friend is child porn!! If the simple act of viewing an image of someone is harmful perhaps an appropriate punishment would be to simply take a photo of the perpetrator in jail, then set them free, but have some look at the photo that was taken while they were in jail.