Cryptographically attestable anti-tampering sensors

To be able to securely report a reading (from any kind of sensors), the combination of the following is necessary:

• a cryptographic attestation of the sensor reading, authenticating the origin of the measure: each device has a private key signing outgoing payloads (with a nonce to avoid replays)
• an anti-tampering installation of the reader device, rendering it inoperable (by wiping the private key) in case of manipulation attempt (connect to another object, inject false stimuli, etc.)

These secure reading devices are called Hardware Oracles, and are the gateways from the physical work to the Blockchain realm.

Source: Hardware Oracles: bridging the Real World to the Blockchain