I wish there could be added a signature to GDPR export, that can be validated. This way you can transfer data to a new platform and the new platform can trust

I wish there could be added a signature to GDPR export, that can be validated. This way you can transfer data to a new platform and the new platform can trust that the information is not manipulated. Let me and a couple of friends move out of Facebook and bring all our prior interactions with us. (The signature should be invalid after example one month to avoid the value of data breaches, with periodic signature key release)