In an interview with The Dong-A Ilbo, lawyer and handwriting researcher Koo Bon-jin stated,
“Counterfeiting an entire handwriting style is virtually impossible. Ahn Jung-geun’s script is a quintessential form influenced by the Tang dynasty calligrapher Yan Zhenqing (709–785). The brushstrokes, ink tone, and various other elements match without the slightest room for doubt.”
https://www.donga.com/news/Culture/article/all/20250814/132182848/1