There are a few targeted inner questions within your main question, I'll call attention to each part as we go -- as always, I'll be happy to revise or clarify if I miss something. I suppose it is only a closely guarded secret because much of the reasoning for it working come back to cryptographic details as a function of the Public Key Infrastructure system that backs Apple's provisioning -- This stuff gets deep fast so it is considered by some to be [dark] magic. Hopefully this will shine some light on what is going on!
TL;DR Version
Yes you can, but it is technically an unsupported use case that may change at any time. This works because what information iTunes Connect chooses to validate does not include the single differentiating factor between an App Store and AdHoc distribution provisioning profile. Since this is technically not a permitted configuration, I'd advocate for at least having a backup plan since Apple may change iTunes Connect validation policy at any time breaking this submission edge case.
Now for the curious, the here is the rest of the story...
Can you submit Adhoc-signed IPA to Appstore / iTunesConnect, and have it pass Apple verification and eventually be distributed through Appstore[?]
As of this specific iteration of iTunesConnect and the Application Loader (4 Sept 2014 / Xcode 5.1.1), yes you can submit an AdHoc signed build and have it accepted through the pipeline. The eagle-eyed reader will note that my 'Yes' comes with a built-in escape hatch -- Because of the data encoded in AdHoc vs App Store provisioning profiles is nearly identical coupled with what parts of these files iTunesConnect is actually using for validation, an AdHoc provisioning profile presents to the delivery pipeline in the same manner as the AppStore version of the same app.
Should the provisioning format change between AdHoc and App Store files to explicitly differentiate the two types of Distribution provisioning profiles or should Apple iTunesConnect engineers change server-side validation rules, it is distinctly possible that this undocumented behavior will stop working. Of course we all know that we are supposed to use the App Store provisioning profile, as per Developer documentation in the App Distribution Guide > Submitting Your App > About Store Provisioning Profiles (https://developer.apple.com/library/ios/documentation/IDEs/Conceptual/AppDistributionGuide/SubmittingYourApp/SubmittingYourApp.html#//apple_ref/doc/uid/TP40012582-CH9-SW32) [emphasis added]:
A store distribution provisioning profile contains a single App ID that matches one or more of your apps, and a distribution certificate. For iOS apps, you need a store provisioning profile to submit your app.
...but this other avenue works for now. If you do choose to use this avenue, you just need to be aware that it is not the documented behavior and thus would be subject to change at any point in time, likely without advanced notice. Since it is skirting the edges of submission requirements it would probably be good to at least have a backup plan setup for the case of Apple changing provisioning or iTC validation requirements -- Murphy's law would dictate that these validation changes would happen at the most inopportune time.
Stepping off the 'Best Practice' Soapbox and turning to the technical side of things...
Why [does this work]?
As you may or may not know, provisioning profiles are composed of exactly 1 appId, one or more signing certificates, and zero or more test devices.
Related Reading: I've got a longer answer to What are code signing identities? that speaks in more detail to the parts of the codesign process.
In this case the question is 'why do AdHoc profiles work when the documentation says you need to have an App Store profile?'
The guts of a provisioning profile contain a cryptographically signed .plist that includes the information identified above, plus some additional metadata. On an OS X machine you can open Terminal and run:
security cms -D -i path/to/AdHoc.mobileprovision
...and in a separate Terminal window run the App Store profile equivalent:
security cms -D -i path/to/AppStore.mobileprovison
These commands will dump out the plist portion of the provisioning profile to their respective Terminal windows. When you scroll through the contents of both windows you will note that the following sections are identical:
- AppIDName
- AppliationIdentifierPrefix
- DeveloperCertificates
- Entitlements
- TeamIdentifier
- Version
The profile's metadata are different, but those are entirely expected differences that only matter for validating profile validity, or for humans interrogating the profile:
- CreationDate
- ExpirationDate
- Name
- TimeToLive
- UUID
The salient points to take away are:
- The
DeveloperCertificates blocks are identical between both profiles.
- The AdHoc profile only adds information (
ProvisionedDevices) to the structure and format of the App Store profile.
The contents of the DeveloperCertificates array is the DER encoded X.509 iPhone Distribution Certificate -- The exact same as the one in your keychain. Is is important to note that this DER data is only the public portion of your Distribution certificate public-private keypair, and it can only be used by others to authenticate the application's signature came from you -- It can not be used to resign a binary as you.
If you paste the contents of DeveloperCertificates:Array:Data element into an ASN.1 decoder (http://lapo.it/asn1js/) and compare the elements of the output to the information encoded in the Distribution certificate included in the Keychain, you'll find that it is an exact copy of the public Distribution certificate you downloaded from Apple after submitting your Certificate Signing Request though the Certificates, Identifiers, and Profiles tool.
Because both the AdHoc and App Store provisioning profiles use the same public key certificate as their signing identity, they are inherently using the same private key when generating the application's signature. This means that the signature generated when signing with an AdHoc profile is functionally identical to one generated when signing with the App Store profile
When Apple performs a signature validation on iTunes Connect during the submission process, both and AdHoc signed cryptographic signature and an App Store signed cryptographic signature will successfully validate against the Distribution Certificate Apple has on file as both provisioning profiles are backed by the same Distribution Certificate.
So the signatures match, but why doesn't the extra information in AdHoc profiles trip up the submission?
Your original question suggests that you have familiarity with iOS' app install policies. For the benefit of someone stumbling across this answer in the future I'll briefly summarize:
iOS operates on a 'deny-all unless specifically permitted' policy. That is, iOS assumes you are not allowed to install an app unless a specific 'grant' has been allowed. For devices coming from the App Store, the app's signature includes Apple's App Store identity for which iOS has a specific 'grant' privilege. AdHoc installs by default fall under the 'deny' policy and the ProvisionedDevices section of a Development or AdHoc profile are the specific 'grant' privileges. The app will install outside of the App Store if all of the following hold true:
- The application's cryptographic signature is valid
- The application's embedded provisioning profile's cryptographic signature is still valid (the profile hasn't been tampered with)
- The application's embedded provisioning profile's
ExpirationDate hasn't passed and the current time isn't before the CreationDate
- The embedded profile or a profile installed to the device match the AppId being proposed for installation.
- The embedded profile or a profile installed to the device contain an entry in
ProvisionedDevices that exactly match the device's UDID.
As we saw above, the app identity and signing information is identical between an App Store profile and and Ad Hoc profile -- the addition of ProvisionedDevices serves only to add these 'grant' privileges for an external (outside of App Store) distribution mechanism. It turns out that iTunes Connect / Application Loader validation is currently only validating that a Distribution profile was used for the app's signature, not that the profile that was used was an App Store profile instead of an AdHoc profile.
This boils down to the fact that the as of Version 1 (ala Version block in the plist) the only differentiating factor between AdHoc and App Store distribution profiles is the presence or absence of the ProvisionedDevices block. It turns out that as of today, this is not a detail that Apple looks for when interrogating the profile that was used, thus the binary passes the automated portions of app verification. They definitely do check that the AppId in the profile matches what the App claims, that the signing identity matches what was used to sign the binary, expiration dates, and any entitlements used match what is found in the automated scan of the app, in addition to the items you highlighted in your original question (version checks between iTunes Connect and the info.plist, iconography presence, iconography sizes, etc.)
Hypothetically, in a subsequent iTunes Connect / Application Loader update, they could start checking for the absence of this key in the embedded.mobileprovision profile that exists within the submitted binary and auto-reject the submission on the grounds that an App Store profile was not used. Similarly, if the provisioning profile format was updated (ex. Version=2) they could add a new element that explicitly calls out the type of profile and auto-reject if it isn't an App Store type. It could perhaps look like this:
<key>ProfileType</key>
<integer>1</integer>
Where the integer value could be 1, 2 or, 3 depending on the type of profile in use, consistent with the formats used in things like Info.plist for identifying supported device families (iPhone-only, iPad-only, or Universal). This would clarify other questions that have been asked about identifying the type of build.
Related Reading:
So, this makes me think Apple just strips out mobile provision when distributing through Appstore.
Yes they do! If you look at archived versions of the apps you submitted you'll find that the contents of the app contain embedded.mobileprovision -- if you then go download the same version from the App Store, you'll find that file missing. Apple only uses embedded.mobileprovision to verify the contents of your app during the submission and review process. When the app is 'Processing for App Store' the final package is assembled and the embedded profile is removed.
