Consider bumping minimum iOS / tvOS version to 13

[vcsjones]

Today our floor for iOS version support is 12.2.

runtime/Directory.Build.props

Line 42 in b87db0a

<iOSVersionMin>12.2</iOSVersionMin>

Over at #116511 we are looking at implementing support for SHA-3 using CryptoKit.

While SHA-3 is Apple 26 and later, MD5/SHA-1/SHA-2 have been in CryptoKit since it was introduced in iOS 13.

If our iOS floor is iOS 13 (and tvOS) then we can implement SHA-3 with CryptoKit, and we can implement all of the other hash algorithms in terms of CryptoKit as well. This would substantially reduce the complexity of introducing SHA-3, as we won't have two different implementations of hash algorithms. The CommonCrypto one will just go away, and the SHA-3 implementations will just light up using if #available(iOS 26, etc, *).

This also benefits HMAC as well.

[dotnet-policy-service]

Tagging subscribers to 'os-ios': @vitek-karas, @kotlarmilos, @steveisok, @akoeplinger
See info in area-owners.md if you want to be subscribed.

[dotnet-policy-service]

Tagging subscribers to 'os-tvos': @vitek-karas, @kotlarmilos, @steveisok, @akoeplinger
See info in area-owners.md if you want to be subscribed.

[vcsjones]

Any early feedback on this would be appreciated. If this is possible then great, but if we want to stick with 12.2 it's not a deal breaker, but knowing earlier will help figure out the t-shirt size between Medium and Large.

[vitek-karas]

@davidortinau any idea of impact on MAUI?

[vcsjones]

My understanding of this would be the following devices would not longer be "supported".

1. iPhone 5s (2013)
2. iPhone 6 / 6 Plus (2014)
3. iPad Air gen 1 (2013)
4. iPad mini 2 (2013) and iPad mini 3 (2014)

[vitek-karas]

Adding @rolfbjarne - we need to align this with MAUI/iOS-SDK support policy, whichever way we go.

[rolfbjarne]

Personally I wouldn't be opposed to this, but I think we need some numbers on how many users this would affect.

• https://iosref.com/ios-usage: iOS 12 = ~0.8%
• https://telemetrydeck.com/survey/apple/iOS/majorSystemVersions/: iOS 12: ~0,016% (it's invisible in the graph, so I had to get the CSV to calculate this).

Another point is that iOS 12 is a bit weird, because it got updates from Apple way after iOS 13 and iOS 14 last got updates: https://endoflife.date/ios (last iOS 12 update was 23 Jan 2023).

CC @davidortinau any thoughts?

[akoeplinger]

I think we're fine with bumping to iOS13 given the numbers for iOS12 today and when net11 will actually be released.