Aron Stacey, 38, of Accrington, east Lancashire, swapped child abuse images and videos with an Israeli man in an online photo sharing website and they discussed child abuse together.
Stacey, who ran Aztec Martial Arts in Accrington, was arrested in September 2017.
Safeguarding checks were made where Stacey held his martial arts classes and no complaints or disclosures were made by his students who included children. There was no evidence that Stacey had committed other offences.
Earlier this month at Preston Crown Court, Stacey admitted making 11 category A (the most severe) images of children, possessing one category B image, possessing 27 category C images, distributing one category A image, and possessing extreme pornography portraying sexual intercourse with an animal.
He also admitted failing to disclose the passcode to his phone.
Stacey made no comment to the majority of questions in interview with NCA officers.
But he claimed his laptop was bought second hand though he did not explain where from.
NCA investigators got into his phone to discover an added layer of encryption.
Stacey repeatedly refused to share his password.
NCA operations manager Hazel Stewart said: “Offenders cannot hide behind encryption and evade justice.
“Behind every sexual abuse image is a child whose life has been utterly devastated and men like Stacey are perpetuating that suffering. Their horrible interest fuels the market in child sexual abuse.
“UK referrals of child sexual abuse material are rocketing. They are up from 43,072 in 2016 to 113,948 in 2018.
“We and UK police arrest around 500 child sex offenders a month and safeguard about 700 children a month.”
Child Protection Charity The Lucy Faithfull Foundation runs the Stop It Now! helpline which offers confidential advice to anyone concerned about their own or someone else’s behaviour towards children.