[aiiane]

No, the daily key is not broadcast; instead it's used to generate a series of rolling identifiers to broadcast. The rolling identifiers change much more frequently. The daily keys don't leave the device until/unless filing a positive diagnosis report.

[xiphias2]

As we know from the Bitcoin wallet problems, generating random private key and verifying that it's random is an extremely hard problem. For this reason I wouldn't use any contact tracing app that is not open source.

[rubatuga]

You should be happy to know that it's opt in