You can sign it. Actually, ownership of keys doesn't prove this at all. It proves you have the keys now, but not that you owned them at the time.
This is why you sign it using your identity. Keys are not identity.
What the chain says
- Block
- 678 138
- Time
- 2021-03-12T17:48:12Z
- Signer
- 1M7VtozkKiQiAVTBjupkVMxCibUcmQPh3
- App
- twetch
- Type
- post
- Content type
- text/plain
Fields the transaction did not carry are omitted. Open the payload to see the bytes as stored.
Signed by
1M7VtozkKiQiAVTBjupkVMxCibUcmQPh3 Verified