With Nicholas J. Hopper and John Langford , he was the first to provide rigorous definitions of steganography and to prove that private - key steganography is possible .
Von Ahn 's early research was in the field of cryptography .
With Nicholas J. Hopper and John Langford , Von Ahn was the first to provide rigorous definitions of steganography and to prove that private - key steganography is possible .
Von Ahn 's early research was in the field of cryptography .