A cyber jihadi who used a James Bond-style cufflink to conceal his support for Islamic State will be sentenced later.
Samata Ullah, 34, pleaded guilty to five terror offences, including membership of IS, training and preparation of terrorist acts.
At the time of his arrest in Cardiff on September 22 last year, he had a USB cufflink with a Linux operating system loaded on to it to conceal a hoard of extremist data.
British counter terrorism police had tracked him down after being passed intelligence from authorities in Kenya, who had arrested another man.
Ullah, who has been diagnosed with autism, was in regular contact with the man and discussed developing special skills to help in the IS campaign, Scotland Yard said.
Officers found he was an active member of IS and had helped other like-minded extremists by teaching them how to keep their activities secret.
From December 2015, he had provided instructional videos on how to secure sensitive data and remain anonymous online with the use of the Tor programme and PGP (Pretty Good Privacy) encryption.
He developed a website on computer hacking and kept numerous extremist documents and videos on electronic devices at his Cardiff home, including the USB cufflink.
Ullah admitted researching ZeroNet and developing a version of a blog site using the decentralised internet-like peer-to-peer network.
He also pleaded guilty to having a book entitled Guided Missiles Fundamentals AFM 52-31 and an electronic PDF version of Advances In Missile Guidance, Control And Estimation for terrorist purposes.
However, he denied a charge of directing terrorism between December 2015 and September last year contrary to section 56 of the Terrorism Act 2000, which will lie on court file.
Commander Dean Haydon, of the Met's Counter Terrorism Command (SO15), said: "Just because Ullah's activity was in the virtual world, we never underestimated how dangerous his activity was.
"He sat in his bedroom in Wales and created online content with the sole intention of aiding people who wanted to actively support Isis and avoid getting caught by the authorities.
"This is just the sort of information that may have helped people involved in planning devastating, low technical level attacks on crowded places as we have seen in other cities across the world.
Last month, Detective Superintendent Lee Porter, head of the Wales Extremism and Counter Terrorism Unit (WECTU), said: "Ullah's activities came as a shock for those who knew him, including his family and the local community.
"His actions and desires do not represent the people of Cardiff or Wales who have repeatedly voiced and demonstrated their resilience to extremist views."
Ullah will be sentenced by Judge Gerald Gordon at the Old Bailey later.