Nikon Image Authentication Software Cracked, Rendered Useless

by on April 29, 2011

in Nikon

Image authentication doesn’t quite mean what it used to.  It was just back in November 2010 that Russian forensic software firm, ElcomSoft, cracked Canon’s image authentication software.  Now, it’s done the same to Nikon’s $500 Image Authentication Software.

Nikon states that its Image Authentication Software allows users to “Verify JPEG, TIFF and NEF (RAW) data taken using a compatible Nikon digital SLR. This secure software checks if an image has been processed or edited after taken.”

The authenticity of a photograph is of the utmost importance in court cases and other commercial and industrial applications.  The discovery of vulnerabilities in Nikon’s software adds yet another hurdle to a previously proven method of image authentication.

ElcomSoft claims that it has notified Nikon of this vulnerability; however, ElcomSoft noted that “Nikon has provided no response nor expressed any interest in the existence of the issue.”

Note that Canon Europe posted a request of users of its software to contact the company to discuss the issue.

More details on this development in Elcomsoft’s statement below.

Moscow, Russia – April 28, 2011 – ElcomSoft Co. Ltd. researched Nikon’s Image Authentication System, a secure suite validating if an image has been altered since capture, and discovered a major vulnerability in the manner the secure image signing key is being handled. In turn, this allowed the company to extract the original signing key from a Nikon camera. The vulnerability, when exploited, makes it possible to produce manipulated images with a fully valid authentication signature. ElcomSoft was able to successfully extract the original image signing key and produce a set of forged images that successfully pass validation with Nikon Image Authentication Software.

ElcomSoft has notified CERT and Nikon about the issue, and prepared a set of digitally manipulated images passing as originals when verified with Nikon’s secure authentication software. Nikon has provided no response nor expressed any interest in the existence of the issue.

About Nikon Image Authentication System

Combined with digital signature modules featured in Nikon’s top of the line digital SLRs, the purpose of Nikon Image Authentication Software was to enable users determine whether an image has been altered after being shot. By Nikon’s claims, the system was to provide proof of image authenticity for the purpose of law enforcement and government agencies, insurance companies, businesses, and news agencies. As demonstrated by ElcomSoft, claims made by two major digital camera vendors, Canon and Nikon, have so far not lived up to the hype.

Background

Credibility of photographic evidence may be extremely important in a variety of situations. Courts, news agencies and insurance companies may accept digitally signed photographs as valid evidence. If such evidence is forged, consequences can be severe. The most famous fakes include cases of fraud committed by enthusiast photographers, photo journalists, editors, political parties, and even the US Army.

To address the issue, major manufacturers of photographic equipment such as Canon and Nikon developed their own proprietary versions of image authentication systems. In 2010, ElcomSoft performed a security analysis of Canon’s proprietary image authentication system. Similar to Nikon’s, the system was supposed to prove image authenticity in the eyes of the media, law enforcement, government, and business organizations. As demonstrated by ElcomSoft, a major security flaw exists in Canon’s implementation, which has not been addressed in any way even today, after half a year after discovery.

Almost half a year later, ElcomSoft has discovered that a similar vulnerability exists in digital SLR cameras manufactured by Nikon. The existence of this vulnerability proves that image authentication data can be forged, and thus Nikon Image Authentication System cannot and shall not be relied upon. As a consequence, successful image verification as reported by Nikon Image Authentication Software cannot be used as a proof of authenticity.

The Issue with Nikon’s Security System

When designing a digital security system, it is essential to equally and properly implement all parts of the system. The entire system is only as secure as its weakest link. In the case of Nikon’s Image Authentication System, the company has not done at least one thing right. The ultimate vulnerability lies in the way the image signing key is being handled. As the signing cryptographic key is handled inappropriately, it can be extracted from the camera as shown by ElcomSoft researchers. After obtaining the signing key, one can use it to sign any picture, whether or not it’s been altered, edited, or even computer-generated. The signed image will then successfully pass as a valid, genuine piece when verified by Nikon Image Authentication Software.

The vulnerability exists in all current Nikon cameras supporting Nikon Image Authentication, including Nikon D3X, D3, D700, D300S, D300, D2Xs, D2X, D2Hs, and D200 digital SLRs.

ElcomSoft will share some technical details on one of the security conferences in near future. Full detail will not be disclosed in the interests of public responsibility. The vendor and CERT Coordination Center have been notified of the issue. While ElcomSoft has contacted most Nikon’s branches, including Nikon USA, Nikon Europe and Nikon Japan, the company provided no meaningful response and did not appear concerned about the issue in the least.

ElcomSoft has performed the extraction of the signing key, and, as a proof of concept, prepared a set of forged images that pass as fully genuine. The fakes successfully passing validation with Nikon Image Authentication Software are available at http://nikon.elcomsoft.com

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{ 4 comments }

1 David Dillard April 29, 2011 at 8:49 am

To be clear, it’s not the they cracked the Nikon software – they didn’t, nor did they need to. They managed to extract the private key from a camera. The private key is used to digitally sign the image that the authentication process uses. As the name implies, the private key is supposed to be private. If it becomes public then all is lost.

Given this, this hack may not affect all Nikon camera models that support Image Authentication. Different camera models may have different hardware which may require different methods of extracting that private key – and some may not be vulnerable. Of course, I’d be skeptical that any model is safe at the moment.

Unfortunately, their blog post doesn’t say how they extracted the key. Does it require specialized hardware and disassembly of the camera? Or can it be done over USB? There’s a big difference between the two.

2 Martin April 29, 2011 at 4:12 pm

Dear David,

After checking on nikon.elcomsoft.com for additional information, the EXIF data of all 4 forged sample images lists a D3X camera, this might support that the signing key from 1 camera (i.e. a D3X) has been extracted and used.

However, Elcomsoft state explicitly that all current Nikon cameras with image authentication are affected. Additionally, Elcomsoft state in their blog (blog.crackpassword.com/2011/04/nikon-image-authentication-system-compromised): ‘The private signing key has been compromised, which automatically invalidates digital signatures placed by all current models manufactured by Nikon.’

To me this indicates that the same signing key is used by all current Nikon cameras, and not only that the signing key can be extracted from all cameras. Consequently, Nikon’s current authentication system as a whole, including all cameras, is severely compromised.

3 David Dillard April 29, 2011 at 5:03 pm

Hmm… I’m starting to wonder if Nikon did something incredibly stupid and used the same public/private keys in ALL of their cameras with this feature. That would make manufacturing the cameras much easier, but it’s a total disaster from a security perspective.

The sad thing is that once Canon had been compromised Nikon had to know they’d be the next target and thus would have examined their system to see if it was vulnerable or not. Hopefully, they have a fix in the works, but I doubt it will work in any existing models.

4 George Norkus May 7, 2011 at 1:02 am

Remember when you could say; “My word is my bond.”? The digital age threw that one out the window!

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