Apple’s battle with the F.B.I. over unlocking an iPhone used by one of the San Bernardino shooters has ended after the government said on Monday that it had managed to access the data on its own. But the resolution of the legal drama raises a new question: If the F.B.I. can unlock the phone, can anyone else?

The answer is a potential public relations black eye for Apple, which brags about its iPhone encryption as an effective wall against hackers. On the other hand, the F.B.I.’s technique, which went undescribed in court papers, could merely work on the one phone in the case, a 5c with an iOS 9 operating system.

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It’s not clear from the little details provided by the F.B.I. whether the bureau discovered a universal flaw in Apple’s software that it was able to exploit or a workaround limited to the disputed device. Additionally, it’s uncertain if the F.B.I. was able to use some sort of physical method to open up the phone’s case, and retrieve and read encrypted data from the device’s memory chips.

However, one thing is clear: Apple has been steadfast in its belief that its operating systems are nearly impervious to hackers.

Apple previously told a U.S. judge in another lawsuit that recent security upgrades to its technology have made it “impossible” for the company to unlock devices running with mobile operating systems iOS 8 and higher. However, the fact that the F.B.I. was able to retrieve the data it sought indicates that what Apple aapl once said was impossible, is in fact possible.

If the F.B.I., with the help of a third party, has indeed discovered a flaw in Apple’s mobile operating system, it’s likely that Apple engineers will work overtime to try to discover the vulnerability. A law enforcement official told media outlets on Monday that the F.B.I. would not comment on whether it will tell Apple how it broke into the phone.

It’s also unclear how the F.B.I.’s announcement will play into roughly a dozen other cases in which the F.B.I. has compelled Apple to help it break into other encrypted iPhones. If whatever method the F.B.I. used to obtain the data from the San Bernardino shooter’s iPhone can be applied to other cases, Apple’s iPhone security credibility will be further damaged.

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Now the pressure is on Apple to prove to customers that its upgraded iPhone operating systems are as secure as the company claims. The legal battle may be over for Apple, but a new one to reassure the public is likely just getting started.