Guardtime is a software company that developed a digital signature system based on blockchain technology. Company’s main partners are in the defense and aerospace industries. They provide anti-tamper hardware solutions for defending critical networks from nation-state level attackers. They design and tailor network defenses, providing end to end data-centric security for sensor platforms.

Guardtime was founded in Estonia in 2007 by Martin Ruubel, who brings knowledge from leadership roles in five different startups, and Ahto Buldas who is a professor at Tallinn University of Technology. In 2007 Estonia was subjected to mass cyberattacks in the wake of relocating a Russian World War II war memorial. The idea of going beyond defending the physical perimeter took root, and with a team of IT developers, security architects and cryptographers, Guardtime was founded.

KSI, or. Keyless Signature Infrastructure, is a blockchain technology that provides massive scale data authentication without the reliance on centralised trust authorities. It allows organisations to detect changes in the integrity state of monitored digital assets in real-time. A KSI service ingests a hash value representing data and returns a KSI Signature that can be used to independently assert the integrity of the data, the signing time and signing entity of that data.

Their main product, the Black Lantern Security Appliance, is a self-protecting security appliance technology that enables organisations to ensure the integrity of their networks, prevent the loss of critical digital assets and track data securely throughout its supply chain.  It defends itself against both remote and physical attacks, meaning that all operating software is signed and encrypted, and it reports any attempts of tampering.

Their KSI technology and anti-tamper hardware solutions are used in digital advertising, e-government systems, telecommunications, the defense and aerospace industries and in the financial markets.

The company also has a presence in the Netherlands and the US. Its key clients are Ericsson and two American defense giants, Lockhead Martin (a global aerospace, defense, security and advanced technologies company) and Raytheon (a defense contractor and industrial corporation).

Guardtime gained first place at the global startup competition, Innotribe, in 2011 and was awarded with an 1.8 million-dollar contract to formally verify a Blockchain-based integrity monitoring system.