This is a database of SHA256 and SHA512 hashes of Apple firmware updates. Extracted from Apple firmware updates and OS updates.
Apple firmware updates website: https://support.apple.com/en-us/HT201518
There are no official signatures (yet) available from Apple. This would be a very useful thing for Apple to make available.
I'll keep adding older versions as I'm able to track them.
My PGP key is available here: https://reverse.put.as/wp-content/uploads/2008/06/publickey.txt
Key Fingerprint: 7B05 44D1 A1D5 3078 7F4C E745 9BB7 2A44 ED41 BF05