This is the most secure authentication method ever. Why, because its utilize yourself, your body parts as the tool to authenticate yourself. This method was created because people was starting to forget their password, and losing their stuff for the authentication. Currently this method is only implemented in a large and sensitive corporation to prevent something or someone from the outside to access their assets. Some body parts that usually used for this kind of authentication are face, retina, fingerprint, voice, or even DNA.
Attackers will likely having difficulty to bypass this authentication method. If the authentication need to scan the fingerprint of the owner, the attacker must either steal the finger or the fingerprint of the owner. Whereas stealing the finger without making the owner notice is difficult except killing the owner first. And stealing the fingerprint is not very hard to do. I bet you already seen some technique to steal fingerprint in some movies.
Although this method of authentication is very secure, it still have some problems. First is the reliability. This method is highly depends on the physical condition of the user. Just a little change on the physical condition of the user may result in the rejection of authentication from the system. Second is the cost. This kind of method need a lot of money to be implemented. And for some people who don’t want to pay much money certainly will prefer using password than their body parts to authenticate himself/herself. And the third is the inability to interact with the sensor input devices.Although this is rare, but some people don’t have fingers or even eyes to be scanned by the devices. This make them feels bad and not good for the corporation.
This method of authentication store all of its lets say fingerprint database records on a server. It is possible to compromise the database system itself to add someone else fingerprint in it. Or if the attacker is smart he/she can dump all fingerprint database to be used to impersonate somebody else.