Terminal's "codesign" command trouble

Question

I've been trying to use the "codesign" command on Mail.app so that I can modify the info.plist using the "defaults write" command. It used to work, but after I re-installed Yosemite, I get this result when running the command:

/Applications/Mail.app: no identity found

I ran this command:

codesign -f -s /Applications/Mail.app

If anyone could tell me how I could properly run the codesign command on Mail.app so that I can modify the info.plist of Mail.app using the "defaults write" command, that would be nice! Thanks!

Answer 1

You're just missing a parameter here. I can re-codesign an app using --force and specifying exactly which signature I want to use:

$ codesign --force -s "Developer ID Application: Michael Dautermann" Mail.app
Mail.app: replacing existing signature

And if you want to verify that Mail.app is indeed signed, here is what my copy of Mail looks like before I forced my signature onto it:

$codesign --display --verbose=4 Mail.app
Executable=/Applications/Mail.app/Contents/MacOS/Mail
Identifier=com.apple.mail
Format=bundle with Mach-O thin (x86_64)
CodeDirectory v=20100 size=23743 flags=0x0(none) hashes=1179+5 location=embedded
Hash type=sha1 size=20
CDHash=a3920218afa4f082aac98bf486dd797b13fde588
Signature size=4097
Authority=Software Signing
Authority=Apple Code Signing Certification Authority
Authority=Apple Root CA
Info.plist entries=41
TeamIdentifier=not set
Sealed Resources version=2 rules=15 files=262
Internal requirements count=1 size=64