I'm looking for a detailed description of the internal format of signed binaries on OS X. For Windows executable files Microsoft has published the specification but I'm unable to find the equivalent documentation for OS X applications (Mach-O binaries). The man page for the codesign command doesn't describe how the files are modified.
Anyone know where to find this information?
When I faced the same problem I wasn't managed to find any description. It seems that the best way to find out the format is to check out sources of codesign utility. The sources can be found at
http://www.opensource.apple.com/source/security_systemkeychain/security_systemkeychain-55191/src/codesign.h
P.S. It's quite tricky to build them and I failed to do it.
Update: Take a look at the project isign at https://github.com/saucelabs/isign/ in which Apple's codesign was reimplemented in Python and can be run on Linux.