John Graham-Cumming doesn’t call me often, but when he does I take notice. By day, he is the CTO of security giant Cloudflare, but he is also a secular technology historian guided by a good compass. He is best known for successfully leading a campaign to force the British government to apologize to legendary computer scientist Alan Turing for prosecuting him for homosexuality and essentially harassing him until his death. So when he DMed me to say he had a “hell story” – promising “disposable pads! 8-bit computers! Flight attendants smuggle floppy disks full of random numbers into South Africa!” – I replied.
The story he shared centers around Tim Jenkin, a former anti-apartheid activist. Jenkin grew up as “an ordinary racist white South African,” as he described it when I contacted him. But when Jenkin traveled abroad – outside the filters of the police state government – he learned of the brutal oppression in his home country, and in 1974 he offered his aid to the African National Congress, a banned organization trying to overthrow the white regime. He returned to South Africa and became involved as an activist, distributing pamphlets. He always had a passion for gadgets and was adept at creating “leaflet bombs” – devices placed on the street which, when activated, fired anti-government leaflets into the air, which were spread by the wind. Unfortunately, he says, in 1978 “we were robbed.” Jenkin was sentenced to 12 years in prison.
Jenkin has the mind of a hacker – as a child he played with gadgets, and as a teenager he disassembled and assembled his motorcycle. These skills turned out to be his salvation. Working in a carpentry shop, he created models of enormous keys that could open prison doors. After months of secret carpentry and testing, he and two colleagues left prison and eventually made it to London.
It was the early 1980s and the ANC’s efforts were waning. Communication was the problem. Activists, especially ANC leaders, were under constant surveillance by South African officials. “The decision was made to bring the leaders back to the country to be closer to the activists, but to do that they still had to maintain contact with the outside world,” says Jenkin, who was given a mandate to solve the problem. Basic methods such as undetectable ink and sending codes via touch-tone dialing were not very effective. They wanted a communications system that was computerized and indestructible. The plan was called Operation Vula.
Working from his miniature council flat in London’s Islington – nicknamed GCHQ after the top-secret British intelligence agency – Jenkins began teaching himself coding. These were the early days of personal computers, and the hardware was ridiculously faint by today’s standards. The breakthrough in public key cryptography had occurred several years earlier, but there was no readily available implementation. Jenkin was suspicious of off-the-shelf cryptosystems, fearing they might contain backdoors that would give governments access.
Using Toshiba T1000 computer running an early version of MS-DOS, Jenkin wrote a system using the most secure form of cryptography, a one-time block that encrypts messages character by character using a shared key the length of the message itself. Using the program, the activist could type a message into a computer and encrypt it using a diskette containing a one-time set of random numbers. The activist could then convert the encrypted text into audio signals and play them on a tape recorder that recorded them. Then, using a public telephone, the activist could call ANC leaders in London or Lusaka, Zambia, for example, and play the tape. The receiver would exploit a modem with an acoustic coupler to capture the sounds, convert them back to digital signals, and decode the messages using Jenkin’s program.