A tool called Spire from developer "chpwn" can enable iPhone 4 users to run Apple's personal assistant application, Siri, on their handset. Apple still requires authorization for use of Siri, so users must work around this by inserting information from an iPhone 4S and using a proxy server address.
"Spire uses a new method to obtain the files necessary for Siri, so it doesn't have the copyright issues encountered by previous attempts," they wrote. "Similarly, rather than directing all of your traffic through a specific proxy server (and the associated privacy issues), Spire allows you to specify your own proxy server."
The Siri hack was made possible because of a new build of iOS 5.0.1 that Apple quietly released for the iPhone 4S, but quickly pulled. Hackers subsequently discovered that the update allowed a user to collect the files needed for a Siri port without having to break Apple's copyright.
Hackers had previously cracked Siri and offered the ability to port the voice recognition software to the iPhone 4 and fourth-generation iPod touch. But that previous method relied on tools that may have broken Apple's copyrighted works.
Those methods also required users to rely on a fixed proxy server in order to have Siri communicate with Apple's own servers. But this raised privacy concerns, as a user's voice data could be unknowingly intercepted by a third party.
But now the files come directly from Apple's servers, which has led hackers like "chpwn" to believe they are not infringing on the company's copyright. And users can set up their own proxy server to avoid potential security issues.
Bringing Siri to an iPhone 4 requires that users "jailbreak" their device, a term used to describe hacking iOS to allow users to run unauthorized code. Jailbreaking is a potentially warranty voiding process that allows greater customization and freedom, with new features like themes and applications not approved by Apple, but it can also lead to security issues for less experienced users.
Users can set up their own proxy if they already own an iPhone 4S and want to have Siri functionality on another iOS device, or if they have a friend with an iPhone 4S that would share their authentication tokens. The hacker responsible for the Spire tool said they believe some for-pay service will begin to crop up online, allowing users to rent space on a Siri proxy server attached to an iPhone 4S device.
Another possibility, they said, is hackers might find a way to replace Siri entirely, and instead rely on something like Google Chrome's speech recognition application programming interface.
"Spire is far from perfect, but at least at this point in time, it's the best that I can do," they said. "Maybe in the future someone will find a way to evade the authorization requirement, but from my position here that's unlikely."