A couple of things:
- As you can see on the key ring screen, only your Private Key for key 0x37C79606 is on the iPhone. You need to also import your Public key. Once you do, you'll read "ID: 37C79606 Public/Private Keys" under the key user ID/name.
- You cannot use key 0xBFEB029D for signing on the device, since only the Public Key is available. As a matter of fact, SecuMail shouldn't even allow you to select that key for signing. The Sign key selector should only let you select Private Keys. If this is not the case, please let me know.
This is how the signing/verifying process works:
- When signing, the Private Key is used to sign a digest of the message.
- When verifying, the Public Key is used to verify that the digest stored and the digest computed from the message matches.
So, in a nutshell, for signature verification you need public keys. To generate signatures you need private keys.
Let me know if you have any other questions.