iOS S/MIME signing/encryption incompatible with multiple From addresses

Number:rdar://35507215 Date Originated:13-Nov.-2017 07:23 PM
Status:Open Resolved:
Product:iOS + SDK Product Version:11.1
Classification:Security Reproducible:Always
S/MIME signing and encrypting seems to be incompatible with multiple From addresses. I can successfully sign and encrypt mails as long as there's only one From address defined in my mail account. As soon as I add another address, iOS Mail complains that it doesn't find a signing or encryption identity. Encryption is still possible in some weird cases but signing never works.

Steps to Reproduce:
- Create an IMAP + SMTP Mail account with S/MIME signing. 
- Verify that signing and encryption works correctly. 
- Add a second From address to the account.
- Reboot (just to be sure).

Expected Results:
Signing and encryption should still work as long as the From address matching the cert is selected.

Actual Results:
Signing doesn't work (missing signing identity error), no matter what From address is selected.




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