Hanna is among at least a dozen girls believed to have been abducted by the group in the 12 months before April's mass abduction at Chibok boarding school. She spent two months as a hostage, including periods where she was tethered like an animal and beaten for refusing to convert to Islam.
"They tied a rope around my neck and pulled me to the ground," she said in an interview outside the Nigerian capital, Abuja, with America's CBS News.
"They said they would slaughter me."
After receiving weapons training, she was taken three times into battle with the group when they attacked Nigerian security forces. "They took me along with them, strapped bullets to me and told me to lie down whenever they exchange gunfire with Nigerian soldiers," she said.
Details of Hanna's ordeal match other accounts given by women kidnapped by Boko Haram.
In one account given to a news agency last year, a female hostage told how she was forced to attract the attention of civilians working with the army. When five men approached her, they were ambushed.
"They cut their throats, one at a time. I thought my heart would burst out of my chest, because I was the bait," she said.
Francois Hollande, the French President, was due to meet Goodluck Jonathan, his Nigerian counterpart, and the leaders of neighbouring African states for a summit in Paris yesterday.
