Embodiments of the present invention provide systems, methods, and computer storage media directed to a proof and attestation service that can confirm the veracity of a claim or a statement of truth based on data dynamically-retrieved from various data repositories. A server device receives, from a client device, a request to determine the veracity of a claim or a statement of truth. The server device is generally a trusted computing device, having privileged-access to a variety of data repositories that the client device may or may not access. The server device can select one or more data repositories based on the claim, obtain results data from the selected one or more data repositories, and evaluate each result to determine whether it corresponds to or contradicts the claim. A veracity score can be calculated for the claim or for a result that corresponds to or contradicts the claim. The server device can generate an attestation notification that includes the claim or the result for communication to the requesting client device. In this way, the client device can utilize the proof and attestation service, facilitated via the server device, to determine a claim's veracity or its calculated likelihood of being true.