Code Signing for macOS: what changed

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1	1		> Note: For Apple Notarization requirements for kernel extensions and applications from Mojave 10.14.5 onwards (for kernel extensions from 7 April 2019 and for developers whose first use of their code signing certificate occurred from 7 April 2019) and for all software from Catalina 10.15 onwards that is not distributed via the App Store, see [[Notarization for macOS 10.14.5+]]
2	2
3	3		## Introduction
4	4
5	5		[[Code signing]] ensures both authenticity and integrity of executables that have been downloaded from wide area networks like the Internet. The discussion below applies equally to App Store distribution and distribution outside the App Store.
6	6
7	7		Code signing is required in [[Portal:iOS\|iOS]]. On [[Portal:Mac\|macOS]] 10.7 and later, it enables programs downloaded from the Internet to be opened without any warnings (if they are signed with an Apple-issued certificate) and it is required when using certain functionality (eg APIs used by debuggers; note that in this case a self-signed certificate that is marked as "trusted" suffices). This functionality is performed by Apple's Gatekeeper software.
8	8
9	9		## The evolution of Gatekeeper
10	10
11	11		Gatekeeper, first introduced in Mountain Lion (10.8, 2012), is a Mac security feature that was designed to protect Apple computers from malicious software. Gatekeeper checks applications against the list of apps that Apple has approved for its App Store or have been code signed by developers who have Apple-issued certificates where the application is not offered through the app store. It does not perform any safety checks by itself, other than that the application wasn't changed since the developer signed it, nor does it offer any guarantees about the developer other than that they are paying Apple \$US 99 per year (aka an "Identified Developer").
12	12
13	13		The original Gatekeeper options introduced in Mountain Lion, accessed from Preferences \> Security and Privacy \> General, were:
14	14
15	15		- App Store
16	16		- App Store and Identified Developers
17	17		- Anywhere
18	18
19	19		By choosing the Anywhere option, the user was once able to entirely disable Gatekeeper. The default setting only allowed the launching of applications from the App Store or from a developer who had signed their application with an Apple-issued certificate.
20	20
21	21		When macOS Sierra was released in 2016, Apple made some important changes to Gatekeeper and limited the the Gatekeeper options to:
22	22
23	23		- App Store
24	24		- App Store and Identified Developers
25	25
26	26		However, you can restore the missing Gatekeeper Anywhere' option in Preferences by opening a terminal and executing the command:
27	27
28	28		$ sudo spctl --master-disable
29	29
30	30		which still works up to and including macOS Catalina. The better, as in more secure, alternative was to instead bypass Gatekeeper by opening the application from the right-click context menu or by control clicking on the application. This still triggered the alert dialog but it now contained an Open button to successfully launch the application. This method of bypassing Gatekeeper still works in macOS Catalina, except that on Catalina you need to launch the application a second time with the control-click or right-click to successfully bypass Gatekeeper - the first time you launch the application Gatekeeper cannot be bypassed whether you control-click or right-click or not.
31	31
32	32		### Big Sur and later on Apple M1 ARM64 processors
33	33
34	34		And then Apple changed the game.
35	35
36	36		When Big Sur is running on an Apple M1 (ARM64) processor, all native ARM64 code must be signed or the operating system prevents its execution; and this new Gatekeeper requirement cannot be bypassed by users. Developers can bypass it by running the following command in an Applications \> Utilities \> Terminal window:
37	37
38	38		`spctl developer-mode enable-terminal`
39	39
40	40		and then going to System Preferences \> Security & Privacy \> Privacy, scrolling down until you see an entry for "Developer Tools", authenticate and then tick the checkbox next to Terminal.
41	41
42	42		Intel executables being run under Big Sur on an Apple M1 processor via Rosetta 2 can still be run even though they are unsigned using the control-click or right-click method to bypass Gatekeeper.
43	43
44	44		For more details, see: [[macOS Big Sur changes for developers\|Big Sur changes for developers: Code signing - Intel vs M1]].
45	45
46	46		## Gatekeeper Dialogs
47	47
48		-	<File:load> security warning dmg leopard en.png\\|Simple warning after opening a downloaded application in Leopard. <File:load> security warning dmg mavericks en.png\\|Default settings are more strict in Mavericks, where they prevent downloaded unsigned apps from being started via double-clicking. <File:load> security warning mavericks context en.png\\|If the application is launched via context menu in Mavericks a simple warning is displayed similar to that of earlier versions. <File:simple> load security warning mavericks en.png\\|Gatekeeper shows a simplified warning, if a code-signed app has been downloaded and launched for the first time. In subsequent launches the program is starts immediately. <File:codesigning.png%7COverview> of code-signing a program written with Lazarus and Free Pascal
	48	+	![](/wiki-images/2/26/Load_security_warning_dmg_leopard_en.png)
	49	+
	50	+	Simple warning after opening a downloaded application in Leopard.
	51	+
	52	+	![](/wiki-images/3/31/Load_security_warning_dmg_mavericks_en.png)
	53	+
	54	+	Default settings are more strict in Mavericks, where they prevent downloaded unsigned apps from being started via double-clicking.
	55	+
	56	+	![](/wiki-images/2/20/Load_security_warning_mavericks_context_en.png)
	57	+
	58	+	If the application is launched via context menu in Mavericks a simple warning is displayed similar to that of earlier versions.
	59	+
	60	+	![](/wiki-images/c/c3/Simple_load_security_warning_mavericks_en.png)
	61	+
	62	+	Gatekeeper shows a simplified warning, if a code-signed app has been downloaded and launched for the first time. In subsequent launches the program is starts immediately.
	63	+
	64	+	![](/wiki-images/1/15/Codesigning.png)
	65	+
	66	+	Overview of code-signing a program written with Lazarus and Free Pascal
49	67
50	68		## Overview
51	69
52	70		The basic steps to sign an application that has been written with Lazarus and/or Free Pascal are:
53	71
54	72		1. Obtain a Developer ID from Apple and install it in your system's key chain.
55	73		2. Note the alphanumeric key of your Developer ID (aka TeamIdentifier).
56	74		3. Sign your application with the codesign command.
57	75		4. Sign your installer pkg with the productsign command.
58	76
59	77		It is not possible to use certificates from third-party providers like Comodo because they will not pass Gatekeeper which requires an Apple developer issued certificate. Also note that you cannot sign Windows applications with the Apple developer certificate (this time you do need a third-party Comodo etc certificate).
60	78
61	79		A macOS application distributed outside the Mac App Store will generally have 3–4 separate layers of signing:
62	80
63	81		- The application itself will be code signed using an application certificate.
64	82		- If the application has an installer, the package file will be signed using an installer certificate.
65	83		- The disk image containing the application or installer will be signed using an application certificate.
66	84		- The disk image will [[Notarization for macOS 10.14.5+\|notarized]], and then the ticket generated by the notary service will be [[Notarization for macOS 10.14.5+\|stapled]] to it.
67	85
68	86		## Gatekeeper requirements
69	87
70	88		- Your application should be standalone with no unacceptable external dependencies. The only acceptable external dependencies are system libraries. All other dependencies should be copied to your MyApp.app bundle folder. Gatekeeper rejects any application that has non-system external dependencies.
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72	90		- All binary files inside MyApp.app should be code signed.
73	91
74	92		- All binary files should be located in standard locations inside the MyApp.app bundle folder. Refer to the table below.
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76	94		\| Location \| Description \|
77	95		\|----\|----\|
78	96		\| Contents \| Top content directory of the bundle \|
79	97		\| Contents/MacOS \| Main executable; helper apps and tools \|
80	98		\| Contents/Frameworks \| Frameworks, dylibs \|
81	99		\| Contents/PlugIns \| Plug-ins, both loadable and extensions \|
82	100		\| Contents/XPCServices \| XPC services \|
83	101		\| Contents/Helpers \| Helper apps and tools \|
84	102		\| Contents/Library/Automator \| Automator actions \|
85	103		\| Contents/Library/Spotlight \| Spotlight importers \|
86	104		\| Contents/Library/LoginItems \| Installable login items \|
87	105		\| Contents/Library/LaunchServices \| Privileged helper tools installed by the ServiceManagement framework \|
88	106
89	107		Standard locations for code inside a bundle
90	108
91	109		Note: No non-binary files should ever be located in the folders specified in the table above.
92	110
93	111		## Using codesign to sign your application
94	112
95	113		1. Sign your application with:
96	114
97	115		``` bash
98	116		codesign -f -o runtime --timestamp -s "Developer ID Application: YOUR NAME (TEAM_ID)" /path/to/bundle.app
99	117		```
100	118
101	119		2. Display basic information about the result of the signing process:
102	120
103	121		``` bash
104	122		codesign -dv -r- /path/to/bundle.app
105	123		```
106	124
107	125		If your application was successfully signed this command will return information similar to this:
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109	127		Executable=/Users/apple/Desktop/your.app/Contents/MacOS/yourappname
110	128		Identifier=org.yourdomain.yourappname
111	129		Format=app bundle with Mach-O thin (x86_64)
112	130		CodeDirectory v=20500 size=101470 flags=0x10000(runtime) hashes=3164+3 location=embedded
113	131		Signature size=9063
114	132		Timestamp=7 Dec 2019 at 18:36:08
115	133		Info.plist entries=16
116	134		TeamIdentifier=<10 alpha numeric digits>
117	135		Runtime Version=10.14.0
118	136		Sealed Resources version=2 rules=13 files=45
119	137		designated => identifier "org.yourdomain.yourappname" and anchor apple generic and certificate 1[field.1.2.840.113635.100.6.2.6] /* exists / and certificate leaf[field.1.2.840.113635.100.6.1.13] / exists */ and certificate leaf[subject.OU] = <10 alpha numeric digits>
120	138
121	139		3. Verify your signature:
122	140
123	141		``` bash
124	142		codesign -vv /path/to/bundle.app
125	143		```
126	144
127	145		If your app was successfully signed this command will return the strings "valid on disk" and "satisfies its Designated Requirement", respectively, after the path to your application.
128	146
129	147		## Using productsign to sign your pkg installer
130	148
131	149		1. Sign your installer pkg file with:
132	150
133	151		``` bash
134	152		productsign --timestamp --sign "Developer ID Installer: YOUR NAME (TEAM_ID)" /path/to/unsigned.pkg /path/to/signed.pkg
135	153		```
136	154
137	155		2. Verify your signature with:
138	156
139	157		``` bash
140	158		spctl -vv --assess --type install /path/to/your.pkg
141	159		```
142	160
143	161		which should yield information similar to this if it was successful:
144	162
145	163		your.pkg: accepted
146	164		source=Developer ID
147	165		origin=Developer ID Installer: YOUR NAME (<10 alpha numeric digits>)
148	166
149	167		## Using codesign to sign your disk image
150	168
151	169		Beginning in macOS 10.11.5, you can apply a code signature to read-only, compressed disk images that you use to distribute content. In this case you do not need to separately sign your application.
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153	171		1. Sign your disk image with:
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155	173		``` bash
156	174		codesign -f -o runtime --timestamp -s "Developer ID Application: YOUR NAME (TEAM_ID)" /path/to/YourImage.dmg
157	175		```
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159	177		2. Verify your signature with:
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161	179		``` bash
162	180		spctl -a -t open --context context:primary-signature -vv /path/to/YourImage.dmg
163	181		```
164	182
165	183		which should yield information similar to this if it was successful:
166	184
167	185		YourImage.dmg: accepted
168	186		source=Developer ID
169	187		origin=Developer ID Application: YOUR NAME (<10 alpha numeric digits>)
170	188
171	189		After 3 February 2020 Apple is fully enforcing notarization for macOS 10.14.5+ (Mojave) with the consequence that the above verification of your disk image will now return information similar to this:
172	190
173	191		YourImage.dmg: rejected
174	192		source=Unnotarized Developer ID
175	193		origin=Developer ID Application: YOUR NAME (<10 alpha numeric digits>)
176	194
177	195		See [[Notarization for macOS 10.14.5+]] for more details.
178	196
179	197		## Updating a signed file
180	198
181	199		Whenever you update a signed file, create a new file. Do not copy a new signed file over an old signed file.
182	200
183	201		Specifically, the code signing information (code directory hash) is hung off the vnode within the kernel, and modifying the file behind that cache will cause problems. You need a new vnode, which means a new file, that is, a new inode. Documented in WWDC 2019 Session 703 All About Notarization - see [slide 65 (PDF)](https://devstreaming-cdn.apple.com/videos/wwdc/2019/703yqvyjv9mi5ur6/703/703_all_about_notarization.pdf).
184	202
185	203		## Ad hoc signing
186	204
187	205		This is especially important on ARM64 M1 Apple processors which require all native code to be validly signed (if only ad hoc) or the operating system will not execute it, instead killing it on launch. To ad hoc sign an application:
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189	207		` codesign --force --deep -s - lazarus.app`
190	208
191	209		or to ad hoc sign an executable file:
192	210
193	211		` codesign --force -s - lazarus`
194	212
195	213		A single dash/hyphen on its own for the identity makes it an ad hoc signature with no certificate.
196	214
197	215		You can check the validity of an ad hoc signed executable with:
198	216
199	217		` codesign -dv -r- lazarus`
200	218
201	219		which should produce output similar to the below:
202	220
203	221		`Executable=/Users/trev/lazarus-src/lazarus`\
204	222		`Identifier=lazarus`\
205	223		`Format=Mach-O thin (arm64)`\
206	224		`CodeDirectory v=20400 size=336137 flags=0x2(adhoc) hashes=10498+2 location=embedded`\
207	225		`Signature=adhoc`\
208	226		`Info.plist=not bound`\
209	227		`TeamIdentifier=not set`\
210	228		`Sealed Resources=none`\
211	229		`# designated => cdhash H"2e6f474452344d6fa42feee3db14a05c14d595a3"`
212	230
213	231		In cases where you have compiled the executable yourself, the macOS linker will ad hoc sign the executable for you in which case you need do nothing. You can check the validity with the command above in which case the CodeDirectory output line will indicate that the linker signed the executable with an ad hoc signature as follows::
214	232
215	233		` CodeDirectory v=20400 size=336032 flags=0x20002(adhoc,linker-signed) hashes=10498+0 location=embedded`
216	234
217	235		## Code signing an x86_64 binary on an aarch64 machine
218	236
219	237		## How to install certificates on a second computer
220	238
221	239		There are two ways to do this:
222	240
223	241		1. using the Keychain Access application; and
224	242		2. using Xcode.
225	243
226	244		### Using the Keychain Access application
227	245
228	246		- On the first computer which has the certificates, open the Keychain Access application and create a new keychain. Now select your existing login keychain, and then My Certificates. Your certificates should be shown on the right. There should be a disclosure arrow on the left side, and selecting that should reveal your private key. Select each certificate, and copy and paste (do not drag or you'll remove it from your login keychain) it into your new keychain.
229	247
230	248		- Copy the newly created keychain from your first computer to your second computer, open it with the Keychain Access application and copy/paste/drag the certificate to your second computer's login keychain.
231	249
232	250		### Using Xcode
233	251
234	252		- On the first computer which has the certificates, open Xcode and go to Preferences \> Accounts, select your account, select the gear symbol in the bottom left, choose Export Apple ID and Code Signing Assets, and then save the file.
235	253
236	254		- Copy the developer profile file you saved on your first computer to the second computer, open Xcode, go to Preferences \> Accounts, select your account, select the gear symbol in the bottom left, and then choose Import Apple ID and Code Signing Assets.
237	255
238	256		## How to check what certificates are installed
239	257
240	258		Once you have created or imported the certificates on your computer, you can check for their presence by opening an Applications \> Utilities \> Terminal and executing the following command:
241	259
242	260		`$ security find-identity -p basic -v`
243	261
244	262		This command will list all available certificates on this computer. Make sure that you can see the presence of the Developer ID Application and Developer ID Installer certificates. If you are a member of more than one team, you may see multiple certificates for each team.
245	263
246	264		You can identify the certificates by the hexadecimal number or by the descriptive name, eg "Developer ID Application: Your Name (AB123456DE)"
247	265
248	266		The ten character alpha-numeric code at the end of your name is your Developer Team ID. If you are a member of multiple developer teams, you will have multiple certificates and the team ID will help you distinguish them.
249	267
250	268		## See also
251	269
252	270		- [[macOS Big Sur changes for developers\|Code signing: Intel vs Apple Silicon]]
253	271		- [[Apple Developer Certificates]]
254	272		- [[Notarization for macOS 10.14.5+]]
255	273		- [[Hardened runtime for macOS]]
256	274		- [[Sandboxing for macOS]]
257	275		- [[Signing and Notarization FAQ]]
258	276		- [[macOS Gatekeeper Debugging Tips]]
259	277
260	278		## External links
261	279
262	280		- [Apple Developer portal](https://developer.apple.com/)
263	281		- [Apple: Code Signing Overview](https://developer.apple.com/support/technical/code-signing/)
264	282		- [Apple: Code Signing Guide](https://developer.apple.com/library/mac/documentation/Security/Conceptual/CodeSigningGuide/)
265	283		- [Apple: TN2206 - macOS Code Signing In Depth](https://developer.apple.com/library/archive/technotes/tn2206/_index.html)
266	284		- [Apple: Code signing x86_64 binaries on aarch64](https://developer.apple.com/forums/thread/673323).
267	285
268	286		---
269	287		From the Free Pascal wiki, page "Code Signing for macOS", as it stood on 2022-02-13 after a change by Trev, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).

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