I think you may be misuderstanding the Public Key advice.
- Back at base, you generate a public/private key pair. (Using say; Crypt::RSA.
- You give the public key to the laptop users.
- Within the script on the laptop, you use that public key to encrypt the numbers and you store the encrypted data in their DBs.
You discard the numbers immediately.
- When they return to base, you can use the private key to decrypt those databases.
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.