All these changes are impressing security experts, even those who have been critical of Apple in the past.
"Your iPhone running iOS 8, properly configured in 3 minutes, is most likely more secure than your laptop, and backed up regularly too," tweeted Nick DePetrillo, of New York security company Trail of Bits.
"If I were [Apple CEO] Tim Cook's second-grade teacher, I'd bump his grade up from a D to a B," Zdziarski told Tom's Guide.
The new security features include: a way to quickly "un-trust" all computers to which a device has been connected; the ability to limit the amount of data your apps collect from you; and the ability to change the default Web browser on the iOS Safari browser.
Perhaps best of all, these new changes won't significantly impact the iOS user experience. That's largely because iOS 8 enables most of its new security features by default instead of possibly confusing users by asking them to set up security measures on their own, as DePetrillo and colleague Jay Little, also of Trail of Bits, told us.
Users need only to manually implement the two-step verification for their iCloud accounts. Once they do, logging into iCloud will take a few seconds longer than it used to, but this extra layer of security will help prevent data theft such as the nude selfies stolen from female celebrities earlier this month.
"Apple hasn't sacrificed much in terms of usability, but I am very surprised nonetheless they made the concessions they did," Zdziarski said. "Overall, I think they're wise decisions, and show Apple's serious about security."
However, Apple could still do more to improve its transparency over security issues. "Apple releases their security and privacy policies in a manner which is difficult to compare to previous revisions. Apple should provide a summary of changes whenever they publish updates to these policies," DePetrillo and Little told us.
No search warrants allowed
Since Edward Snowden's NSA leaks began revealing in June 2013 that many tech companies assist government investigations by turning over suspects' data, privacy advocates have kept an eye on the access that Apple, Google and others have to user accounts and data.
To achieve this, iOS 8 stores users' encryption keys on individual users' own devices, not on Apple's servers. Nothing changes for customers using the phones, but all customer data that passes through Apple's servers will be encrypted from the moment it leaves the user's device to the moment it returns, and Apple will not be able to read or decrypt it.
Even if Apple is served with a subpoena, search warrant or National Security Letter, it won't be capable of complying (with iOS 8 data at least), since it will have no information to turn over to law enforcement.
Apple certainly isn't the first company to think of placing encryption keys on user devices instead of on its own servers. As Zdziarski pointed out on his blog, law-enforcement agencies still have other means by which to access data on iPhones and iPads.
Other experts have pointed out that, should U.S. law change, Apple's policy may have to change as well.
"How long until they [Apple] are required to change this by law? A new CALEA?" tweeted security expert Cris Thomas, a.k.a. Space Rogue.
CALEA refers to the 1994 Communications Assistance for Law Enforcement Act, which mandates that telephone service providers and networking-equipment manufacturers build in backdoors to permit government wiretapping. For several years, the FBI has been seeking White House and Congressional approval to expand CALEA to cover Internet services such as those provided by Apple, Google, Facebook and the like.
Boarding up backdoors
Prior to iOS 8, Apple's mobile operating systems contained "backdoors" that let a knowledgeable party bypass Apple's security measures in order to access and download users' data.
Zdziarksi, who documented the backdoors, said of the discoveries in July: "I am not suggesting some grand conspiracy. There are, however, some services running in iOS that shouldn't be there, that were intentionally added by Apple as part of the firmware and that bypass backup encryption while copying more of your personal data than ever should come off the phone for the average consumer."
Apple responded to Zdziarski, calling the backdoors "diagnostic functions [that] ... provide needed information to enterprise IT departments, developers and Apple."
Nevertheless, a good number of the backdoors have been patched (or perhaps "removed," depending on who you ask) in iOS 8. However, documentation for these changes is not included in the list of iOS 8 security improvements (opens in new tab). That's because the backdoors were technically patched not in the final release of iOS 8, but in a beta version of iOS 8 pushed out to Apple developers earlier this month.
As Zdziarski documented on his blog, Apple did not fix every backdoor and flaw he discovered. Contemporary forensic tools can still be used to copy data from iPhones attached via USB cables to computers. (Previously, they could be accessed over Wi-Fi as well.)
Jill Scharr is a staff writer for Tom's Guide, where she regularly covers security, 3D printing and video games. You can follow Jill on Twitter @JillScharr and on Google+. Follow us @tomsguide, on Facebook and on Google+.