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	+	```text
39	39		spctl developer-mode enable-terminal
40	40		```
41	41
42	42		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.
43	43
44	44		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.
45	45
46	46		For more details, see: [[macOS Big Sur changes for developers\|Big Sur changes for developers: Code signing - Intel vs M1]].
47	47
48	48		## Gatekeeper Dialogs
49	49
50	50		![](/wiki-images/2/26/Load_security_warning_dmg_leopard_en.png)
51	51
52	52		Simple warning after opening a downloaded application in Leopard.
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54	54		![](/wiki-images/3/31/Load_security_warning_dmg_mavericks_en.png)
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56	56		Default settings are more strict in Mavericks, where they prevent downloaded unsigned apps from being started via double-clicking.
57	57
58	58		![](/wiki-images/2/20/Load_security_warning_mavericks_context_en.png)
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60	60		If the application is launched via context menu in Mavericks a simple warning is displayed similar to that of earlier versions.
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62	62		![](/wiki-images/c/c3/Simple_load_security_warning_mavericks_en.png)
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64	64		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.
65	65
66	66		![](/wiki-images/1/15/Codesigning.png)
67	67
68	68		Overview of code-signing a program written with Lazarus and Free Pascal
69	69
70	70		## Overview
71	71
72	72		The basic steps to sign an application that has been written with Lazarus and/or Free Pascal are:
73	73
74	74		1. Obtain a Developer ID from Apple and install it in your system's key chain.
75	75		2. Note the alphanumeric key of your Developer ID (aka TeamIdentifier).
76	76		3. Sign your application with the codesign command.
77	77		4. Sign your installer pkg with the productsign command.
78	78
79	79		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).
80	80
81	81		A macOS application distributed outside the Mac App Store will generally have 3–4 separate layers of signing:
82	82
83	83		- The application itself will be code signed using an application certificate.
84	84		- If the application has an installer, the package file will be signed using an installer certificate.
85	85		- The disk image containing the application or installer will be signed using an application certificate.
86	86		- 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.
87	87
88	88		## Gatekeeper requirements
89	89
90	90		- 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.
91	91
92	92		- All binary files inside MyApp.app should be code signed.
93	93
94	94		- All binary files should be located in standard locations inside the MyApp.app bundle folder. Refer to the table below.
95	95
96	96		\| Location \| Description \|
97	97		\|----\|----\|
98	98		\| Contents \| Top content directory of the bundle \|
99	99		\| Contents/MacOS \| Main executable; helper apps and tools \|
100	100		\| Contents/Frameworks \| Frameworks, dylibs \|
101	101		\| Contents/PlugIns \| Plug-ins, both loadable and extensions \|
102	102		\| Contents/XPCServices \| XPC services \|
103	103		\| Contents/Helpers \| Helper apps and tools \|
104	104		\| Contents/Library/Automator \| Automator actions \|
105	105		\| Contents/Library/Spotlight \| Spotlight importers \|
106	106		\| Contents/Library/LoginItems \| Installable login items \|
107	107		\| Contents/Library/LaunchServices \| Privileged helper tools installed by the ServiceManagement framework \|
108	108
109	109		Standard locations for code inside a bundle
110	110
111	111		Note: No non-binary files should ever be located in the folders specified in the table above.
112	112
113	113		## Using codesign to sign your application
114	114
115	115		1. Sign your application with:
116	116
117	117		``` bash
118	118		codesign -f -o runtime --timestamp -s "Developer ID Application: YOUR NAME (TEAM_ID)" /path/to/bundle.app
119	119		```
120	120
121	121		2. Display basic information about the result of the signing process:
122	122
123	123		``` bash
124	124		codesign -dv -r- /path/to/bundle.app
125	125		```
126	126
127	127		If your application was successfully signed this command will return information similar to this:
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129	129		Executable=/Users/apple/Desktop/your.app/Contents/MacOS/yourappname
130	130		Identifier=org.yourdomain.yourappname
131	131		Format=app bundle with Mach-O thin (x86_64)
132	132		CodeDirectory v=20500 size=101470 flags=0x10000(runtime) hashes=3164+3 location=embedded
133	133		Signature size=9063
134	134		Timestamp=7 Dec 2019 at 18:36:08
135	135		Info.plist entries=16
136	136		TeamIdentifier=<10 alpha numeric digits>
137	137		Runtime Version=10.14.0
138	138		Sealed Resources version=2 rules=13 files=45
139	139		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>
140	140
141	141		3. Verify your signature:
142	142
143	143		``` bash
144	144		codesign -vv /path/to/bundle.app
145	145		```
146	146
147	147		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.
148	148
149	149		## Using productsign to sign your pkg installer
150	150
151	151		1. Sign your installer pkg file with:
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153	153		``` bash
154	154		productsign --timestamp --sign "Developer ID Installer: YOUR NAME (TEAM_ID)" /path/to/unsigned.pkg /path/to/signed.pkg
155	155		```
156	156
157	157		2. Verify your signature with:
158	158
159	159		``` bash
160	160		spctl -vv --assess --type install /path/to/your.pkg
161	161		```
162	162
163	163		which should yield information similar to this if it was successful:
164	164
165	165		your.pkg: accepted
166	166		source=Developer ID
167	167		origin=Developer ID Installer: YOUR NAME (<10 alpha numeric digits>)
168	168
169	169		## Using codesign to sign your disk image
170	170
171	171		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.
172	172
173	173		1. Sign your disk image with:
174	174
175	175		``` bash
176	176		codesign -f -o runtime --timestamp -s "Developer ID Application: YOUR NAME (TEAM_ID)" /path/to/YourImage.dmg
177	177		```
178	178
179	179		2. Verify your signature with:
180	180
181	181		``` bash
182	182		spctl -a -t open --context context:primary-signature -vv /path/to/YourImage.dmg
183	183		```
184	184
185	185		which should yield information similar to this if it was successful:
186	186
187	187		YourImage.dmg: accepted
188	188		source=Developer ID
189	189		origin=Developer ID Application: YOUR NAME (<10 alpha numeric digits>)
190	190
191	191		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:
192	192
193	193		YourImage.dmg: rejected
194	194		source=Unnotarized Developer ID
195	195		origin=Developer ID Application: YOUR NAME (<10 alpha numeric digits>)
196	196
197	197		See [[Notarization for macOS 10.14.5+]] for more details.
198	198
199	199		## Updating a signed file
200	200
201	201		Whenever you update a signed file, create a new file. Do not copy a new signed file over an old signed file.
202	202
203	203		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).
204	204
205	205		## Ad hoc signing
206	206
207	207		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:
208	208
209		-	~~```~~
	209	+	```text
210	210		codesign --force --deep -s - lazarus.app
211	211		```
212	212
213	213		or to ad hoc sign an executable file:
214	214
215		-	~~```~~
	215	+	```text
216	216		codesign --force -s - lazarus
217	217		```
218	218
219	219		A single dash/hyphen on its own for the identity makes it an ad hoc signature with no certificate.
220	220
221	221		You can check the validity of an ad hoc signed executable with:
222	222
223		-	~~```~~
	223	+	```text
224	224		codesign -dv -r- lazarus
225	225		```
226	226
227	227		which should produce output similar to the below:
228	228
229		-	~~```~~
	229	+	```text
230	230		Executable=/Users/trev/lazarus-src/lazarus
231	231		Identifier=lazarus
232	232		Format=Mach-O thin (arm64)
233	233		CodeDirectory v=20400 size=336137 flags=0x2(adhoc) hashes=10498+2 location=embedded
234	234		Signature=adhoc
235	235		Info.plist=not bound
236	236		TeamIdentifier=not set
237	237		Sealed Resources=none
238	238		# designated => cdhash H"2e6f474452344d6fa42feee3db14a05c14d595a3"
239	239		```
240	240
241	241		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::
242	242
243		-	~~```~~
	243	+	```text
244	244		CodeDirectory v=20400 size=336032 flags=0x20002(adhoc,linker-signed) hashes=10498+0 location=embedded
245	245		```
246	246
247	247		## Code signing an x86_64 binary on an aarch64 machine
248	248
249	249		## How to install certificates on a second computer
250	250
251	251		There are two ways to do this:
252	252
253	253		1. using the Keychain Access application; and
254	254		2. using Xcode.
255	255
256	256		### Using the Keychain Access application
257	257
258	258		- 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.
259	259
260	260		- 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.
261	261
262	262		### Using Xcode
263	263
264	264		- 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.
265	265
266	266		- 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.
267	267
268	268		## How to check what certificates are installed
269	269
270	270		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:
271	271
272		-	~~```~~
	272	+	```text
273	273		$ security find-identity -p basic -v
274	274		```
275	275
276	276		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.
277	277
278	278		You can identify the certificates by the hexadecimal number or by the descriptive name, eg "Developer ID Application: Your Name (AB123456DE)"
279	279
280	280		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.
281	281
282	282		## See also
283	283
284	284		- [[macOS Big Sur changes for developers\|Code signing: Intel vs Apple Silicon]]
285	285		- [[Apple Developer Certificates]]
286	286		- [[Notarization for macOS 10.14.5+]]
287	287		- [[Hardened runtime for macOS]]
288	288		- [[Sandboxing for macOS]]
289	289		- [[Signing and Notarization FAQ]]
290	290		- [[macOS Gatekeeper Debugging Tips]]
291	291
292	292		## External links
293	293
294	294		- [Apple Developer portal](https://developer.apple.com/)
295	295		- [Apple: Code Signing Overview](https://developer.apple.com/support/technical/code-signing/)
296	296		- [Apple: Code Signing Guide](https://developer.apple.com/library/mac/documentation/Security/Conceptual/CodeSigningGuide/)
297	297		- [Apple: TN2206 - macOS Code Signing In Depth](https://developer.apple.com/library/archive/technotes/tn2206/_index.html)
298	298		- [Apple: Code signing x86_64 binaries on aarch64](https://developer.apple.com/forums/thread/673323).
299	299
300	300		---
301	301		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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