He attended the Norwegian Institute of Technology, and graduated in chemistry in 1941. His professor was Leif Tronstad, a well-known resistance member during the German occupation of Norway since April 1940. In September 1940 the Secret Intelligence Service established two stations for radio communication; the so-called Skylark A in Oslo led by Sverre Midtskau and Skylark B in Trondheim led by Erik Welle-Strand. Skylark B was operated by students at the Institute of Technology, and after technical difficulties in the initial phase, they established regular contact with the intelligence in London in January 1941. Leif Tronstad was also affiliated with the group. When Welle-Strand left the country, Reksten took over as leader of Skylark B.