Nate uses a scytale to decrypt some messages. It is a very weak encryption method - but it is still useful in cases where the recipient can act faster than the opponent can decrypt (and understand) the message.
Source novelist Jason Matthews may not have encountered a real-life Dominika in his work with the CIA, but "honeypot" school was indeed part of Soviet intelligence training. "In the Soviet Union, they had a school that taught young women the art of entrapment, the art of seduction, for blackmailing intelligence targets," Matthews explained. "They had a Sparrow School in the city of Kazan, on the banks of the Volga River, where young women were taught how to be courtesans. They were called 'Sparrows'."
Based on a 2013 novel of the same name by retired CIA operative Jason Matthews. Before the novel was even finished, Matthews sold the film rights for a seven figure sum. The novel is the first book in a trilogy, with the others being Palace of Treason and The Kremlin's Candidate.
To prepare for the role, Jennifer Lawrence did ballet and practiced a Russian accent for four months, spending three hours a day working with the Hollywood ballet instructor Kurt Froman. She said it was difficult because she had never wanted to dance ballet.
The Russian dub changes Dominika's name to "Veronica," since the name Dominika is practically unheard of in Russian speaking countries.