Convert Base64 to .htaccess

My line is like in .htaccess

Header set Content security policy "script-src & # 39; self & # 39; & # 39; nonce -% {UNIQUE_ID} e & # 39 ;; style-src & # 39; self & # 39; & # 39; nonce -% {UNIQUE_ID} e & # 39 ;;

Please, let me know how to convert % {UNIQUE_ID} e in the base64 value in .htaccess.