Just use RsaCtfTool:```cd /opt/RsaCtfTool./RsaCtfTool.py --publickey /media/DATA/CTF/yubitsec/RSA_II/PublicKey.pem --private --uncipher /media/DATA/CTF/yubitsec/RSA_II/ciphertext```After the launch it only remains to collect the flag:```gh0st3rs@leacher-pc:RsaCtfTool$ sudo ./RsaCtfTool.py --publickey /media/DATA/CTF/yubitsec/RSA_II/PublicKey.pem --private --uncipher /media/DATA/CTF/yubitsec/RSA_II/ciphertext-----BEGIN RSA PRIVATE KEY-----MIIQSgIBAAKCA6Y/////////////////////////////////////////////////////////////////////////////////////////////////////////////////.........AAAAAAAgAAAAAAAAgAAAAAAAAQAAAAAAAAQAAAAAAAAIAAAAAAAAIAAAAAAAAEAAAAAAAAEAAAAAAAACAAAAAAAACAAAAAAAABAAAAAAAABAAAAAAAAAgAAAAAAAAQ==-----END RSA PRIVATE KEY-----[+] Clear text : ?�?�?�;�?�z�?�:���??l�SM?�n?zӃ�ܠ�.??�o�Wy?|?��)3Z>7sC��?m�d(dO����?`ɗ�L�W���4;k�63۲?���?�����Dt��0?����.jp�i`4�??��HvZ'���$#��?2A	��$ʋ�F5ǃ�.Aj?�?�9U�l�e�F�I�R6V�Uv:U��׿?����g��	�?���                                                                             =tG4�2hT?W;)��{<pw����J(hӟ�_�)O�d?�Ыy��Ps?�o��z�W� #����)b�3�?o����,����*h��~$����(U`1��Q�ᯕ�E:]ҏ?�©���l�aQ��^�������-i`g��E�4�a   ��&�5!�?}�>��s�*�s;Pf�B1Lb�Z~��I������5����n�\�h?}��#�Y>�KuoJ(q4�r[?Kt2��Ji,���ɐi?#Iy����hsAe�?I569�e;?"�i�?�|���?4F���"�t����19���G_�xrp�*��쎈*Ԅ��������G*���w����m???CN[F-?�n��;�?mN�                                                                                             ��yL��?�[�\ݓ��t��:�d��+����y1���zHie�)V<� ٤S�<=�0�ix��ڲbkj?�t�p�Z^K�@q�y9_gȸ��EI���x       Z�Q�lˉ��2��2���݋         ?e`��wOl>�I                         �?��[v�??N��b���#� �(�U���ʝ�=;?�2��Pe�?�r�X0Iδ�yVɞ|�/���'�^I�?����B���|���pIzKu�`�8DC#��֮��2O���"�ց?!?\C��R?:l�����f��Q�'�]O�~YUBITSEC{G00D_J0B_BRO_Y0U_MUST_KN0W_H0W_D03S_1T_W0RKS}```
Flag: YUBITSEC{G00D_J0B_BRO_Y0U_MUST_KN0W_H0W_D03S_1T_W0RKS}