One day after a judge ordered Apple to help the FBI access the locked iPhone that was owned by Syed Rizwan Farook, one of the San Bernardino shooters, CEO Tim Cook has spoken out against the decision, confirming that the company will appeal the order.

Judge Sheri Pym said in a ruling that Apple must give “reasonable technical assistance” to investigators attempting to unlock the data on the iPhone 5c. Authorities want Apple to create software that will circumvent the device’s security system, including a feature that erases all data on the iPhone if the passcode is entered incorrectly ten times.

“What the court is essentially ordering Apple to do is custom-build malware to undermine its own product’s security features, and then cryptographically sign that software so the iPhone will trust it as coming from Apple,” wrote Kevin S. Bankston, director of New America’s Open Technology Institute in an emailed statement to PCWorld.

The auto-delete feature has to be activated by the user, but authorities can’t tell if the function has been enabled in this case.

As prosecutors don’t know the passcode, they can’t access Farook’s work-issued iPhone. "Apple has the exclusive technical means which would assist the government in completing its search, but has declined to provide that assistance voluntarily," the prosecutors said.

Apple chief Tim Cook said in a letter to customers that, despite the order, the company won’t be building a backdoor to the iPhone.

We have great respect for the professionals at the FBI, and we believe their intentions are good. Up to this point, we have done everything that is both within our power and within the law to help them. But now the U.S. government has asked us for something we simply do not have, and something we consider too dangerous to create. They have asked us to build a backdoor to the iPhone. Specifically, the FBI wants us to make a new version of the iPhone operating system, circumventing several important security features, and install it on an iPhone recovered during the investigation. In the wrong hands, this software — which does not exist today — would have the potential to unlock any iPhone in someone’s physical possession. The FBI may use different words to describe this tool, but make no mistake: Building a version of iOS that bypasses security in this way would undeniably create a backdoor. And while the government may argue that its use would be limited to this case, there is no way to guarantee such control.

Cook went on to warn of the implications of the government's demands.

The government would have us remove security features and add new capabilities to the operating system, allowing a passcode to be input electronically. This would make it easier to unlock an iPhone by “brute force,” trying thousands or millions of combinations with the speed of a modern computer. The implications of the government’s demands are chilling. If the government can use the All Writs Act to make it easier to unlock your iPhone, it would have the power to reach into anyone’s device to capture their data. The government could extend this breach of privacy and demand that Apple build surveillance software to intercept your messages, access your health records or financial data, track your location, or even access your phone’s microphone or camera without your knowledge.

The December 2 shooting, perpetrated by Farook and his wife, Tashfeen Malik, resulted in 14 deaths and 22 serious injuries at the Inland Regional Center in San Bernardino. It reignited the debate over tech firms weakening their products’ encryption or providing backdoors so authorities can monitor suspects.

Last year, Apple said it would not perform data extractions in response to government search warrants on devices running iOS 8 and later because it could not access the data without the user’s passcode, which it does not possess. Apple added that it has never worked with any government to create a backdoor in any of its products or services, and it never will.