Tool Open source
Let's Seal is an open standard, reference implementation, and free service for proving that a file is unaltered, existed by a certain date, and was sealed by a specific certificate. It preserves native signature formats such as PAdES/X.509 signatures for PDFs and uses OpenTimestamps to anchor time to Bitcoin. Each seal is also recorded in an append-only transparency log with a Bitcoin-anchored root, allowing independent auditing. The project provides a hosted web app, the `sealbot` command-line tool, a REST API and SDKs, and a self-hosted engine with its own certificate authority; verification is available online or offline without an account. The repository states that the engine, SDKs, and standard are open source under the Apache-2.0 license.
1 use taken from transcripts — each links to the moment in the video.
Signs files so others can verify that they have not changed, when they existed, and which certificate sealed them. It preserves native signatures for formats such as PDFs and images, anchors time to Bitcoin, and records seals in an append-only Merkle log.
1 in the library.