Misha Solodovnichenko

Extracting stuff from provisioning profiles

added 11.mar.2017

Say, you’re in a Ruby script, for example, fastlane Fastfile and you need to extract information from .mobileprovision file, like UUID, Team Identifier, Code Signing Identity or whatever. Here’s how.

This all is targeted for iOS development on a mac, but (I think) it might be found usefull in unpredicted ways.

CMS encoded provisioning profile files

If you try to view some provisioning_profile.mobileprovision file contents:

cat provisioning_profile.mobileprovision

you’ll end up with garbage, because provisioning profiles are in Cryptographic Message Syntax (CMS) format. You need to decode it:

# cms - Encode or decode CMS encrypted message
# -D - decode a CMS message
# -i - use infile as source of data (default: stdin)
security cms -D -i provisioning_profile.mobileprovision

That gives you plist xml that you can inspect:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>AppIDName</key>
	<string>App ID Name</string>
	<key>ApplicationIdentifierPrefix</key>
	<array>
		<string>ABC123DEF4</string>
	</array>
	<key>CreationDate</key>
	<date>2042-10-15T15:20:42Z</date>
	<key>Platform</key>
	<array>
		<string>iOS</string>
	</array>
	<key>DeveloperCertificates</key>
		<array>
		<data>%Long human-unreadable Base64 encoded certificate%</data>
		</array>
	<key>Entitlements</key>
	<dict>
		<key>keychain-access-groups</key>
		<array>
			<string>ABC123DEF4.*</string>		
		</array>
		<key>get-task-allow</key>
		<false/>
		<key>application-identifier</key>
		<string>ABC123DEF4.com.your.bundle.id</string>
		<key>com.apple.developer.team-identifier</key>
		<string>U1R23TEAMID</string>
		<key>aps-environment</key>
		<string>production</string>
		<key>beta-reports-active</key>
		<true/>
	</dict>
	<key>ExpirationDate</key>
	<date>2044-10-15T15:20:42Z</date>
	<key>Name</key>
	<string>Profile Name</string>
	<key>TeamIdentifier</key>
	<array>
		<string>U1R23TEAMID</string>
	</array>
	<key>TeamName</key>
	<string>Your team name</string>
	<key>TimeToLive</key>
	<integer>364</integer>
	<key>UUID</key>
	<string>thats-your-profile-uuid-string</string>
	<key>Version</key>
	<integer>1</integer>
</dict>
</plist>

While in Ruby there are number of ways to perform shell commands, fastlane has sh action for shelling out. You can execute shell commands using sh("command") like this:

provision_profile_file_path = "provisioning_profile.mobileprovision"
output_plist_file = "profile.plist"

# Shell out
# This will decode provisioning profile into plist xml
# and save result into the file
sh("security cms -D -i #{provision_profile_path} > #{output_plist_file}")

Extracting plist values in Ruby

Now, when you have the plist file, you can read it and extract values. Since it is just xml, you can use any method you prefer, but I suggest using plist library, you use it like this:

require 'plist'

profile_plist = Plist.parse_xml("profile.plist")
profile_plist['key'] # this returns value for a key

Here are some examples used against plist given above:

require 'plist'

profile_plist = Plist.parse_xml("profile.plist")

profile_plist['UUID']
# => "thats-your-profile-uuid-string"

# `TeamIdentifier` is an array of strings, get the first item
profile_plist['TeamIdentifier'].first
# => "U1R23TEAMID"

Some data is incapsulated, for example, if you need Code Sign Identity or other certificate details, it won’t be surprising that you need to inspect certificates compatible with this provisioning profile.

Extracting code sign identity

List of compatible certificates is stored behind DeveloperCertificates key. It’s an array of Base64 encoded data chunks. You’ll need to Base64 decode them prior to use.

...
<key>DeveloperCertificates</key>
<array>
<data>UkdWamIyUmxJR2R2Yllpd2dibUZoYUMsIG5hYWgsIGp1c3Qgam9raW5nPSk=</data>
</array>
...

If you have Base64 encoded file, you can use this shell command to decode it:

# -D - decode
cat base64_encoded_file | base64 -D

or, without a file:

echo "base64_encoded_string" | base64 -D

But, luckily, if you use the plist library from above, you don’t even need to shell out:

# decode first certificate into string
certificate = profile['DeveloperCertificates'].first.string

If you try to use that string, you’ll notice that it is not much human-readable, also it is not xml. It’s a X.509 DER certificate, you need to decode it, for example via openssl:

# assume your X.509 DER certificate is in `x509_der_cert_file`
# x509 - specifies X.509 standard
# -inform DER - specifies X.509 DER format
# -noout - by default it outputs certificate, this disables it
# -subject - print subject distinguished name
cat x509_der_cert_file | openssl x509 -noout -inform DER -subject

This gives something we could work with:

subject= /UID=U1R23TEAMID/CN=iPhone Distribution: Company Blah/OU=U1R23TEAMID/O=Company LLC/C=RU

CN is code sign identity. I couldn’t resist to introduce more problems, that’s why I extracted CN value via regular expression and sed, here’s what I’ve come up with:

# Groove capture group in the middle, everything between "CN=" and "/"
^.*CN=(.*?)\/.*$

but it does not work with sed (even with -E), so I’ve updated it to:

# Everything between "CN=" and "/" that does not contain "/"
^.*CN=([^\/]*)\/.*$

with sed, if you use “basic regular expressions” you have to escape brackets:

# s for regular expression substitute
# s/regular expression/replacement/flags
# \1 - return capture group 1
sed 's/^.*CN=\([^\/]*\)\/.*$/\1/'

# If you use extended regular expressions you don't need to escape brackets
# -E - interpret regular expression as extended (modern)
sed -E 's/^.*CN=([^\/]*)\/.*$/\1/'

When you shell out from Ruby you’ll need to escape those backslashes again. Here’s a recap:

  1. take (base64 decoded) certificate file,
  2. decode it again assuming it is X.509 DER certificate
  3. extract CN value:
sh("cat #{decoded_cert_file_name} | openssl x509 -noout -inform DER -subject | sed 's/^.*CN=\\([^\\/]*\\)\\/.*$/\\1/'")
# => iPhone Distribution: Company Blah

Here’s also shell version of the complete Code Sign Identity extraction from the base64 encoded certificate file:

cat test_cert.base64 | base64 -D | openssl x509 -noout -inform DER -subject | sed 's/^.*CN=\([^\/]*\)\/.*$/\1/'

I gave you how, but I won’t give you why. Probably, if you need this, you rather doing something really specific or missing the correct and easy way. Make sure it is not the latter.

Bonus

Want Finder preview (select a file and hit Space) be more informative for provision profiles? Like this: ProvisionQL teaser

Than here’s ProvisionQL, it is very useful, and also works for .ipa files. See what it can do.


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