I understand that the iris is the most accurate biometric modality since it has a false acceptance rate of about 1 in 1,000,000. Fingerprint on the other had is about 1 in 1000.

These error rates seem too high in my opinion. If a fingerprint system makes an error after every 1000 tries, then this means airports can allow through a lot of fake people. At a busy airport, an error rate of 1 in 1000 could mean 10 to 50 bad guys going through per day.

Also, for iris, 1 in 1,000,000 seems too high. I thought iris had an error rate closer to zero than this. In a year, you could have a lot of bad guys going through if the error rate is 1 in 1 million.

Could I be missing something when it comes to interpreting these error rates in practice?

  • Yes, you're missing the fact that the bad guys don't know when the fingerprint reader will make a mistake. Aug 16, 2016 at 5:56

2 Answers 2


I don't know about the false acceptance rates of biometric devices.

At a busy airport, an error rate of 1 in 1000 could mean 10 to 50 bad guys going through per day.

Why would you assume that every false acceptance is a bad guy? If you were a bad guy, how could you be sure that you got through when the biometric reader was going to accept a false id (fingerprint/iris)?

Also, it is difficult, if not impossible, to create perfect (unbreakable) systems. There are way too many factors to consider.

This is an acceptable risk, in my opinion. Imagine what would happen if we dismiss the system due to this risk? That would create more problems.


The false acceptance figures of fingerprint biometric are mainly due to old low numbers of matching point and hash number storage, increasing more matching point hash will reduce the false acceptance level.

Currently, it is known truth that current biometric technology unable to make a direct imaging attempt the One-on-One true comparison, it is impossible to scan through millions of data(that will come to petabytes) to look for exact image match in 5 seconds. So retina scan just do the similar works of fingerprint : store selective attributes instead of getting the full data to do fast matching.

Nevertheless, increase biometric attributes matching point will not fix the both biometric problem, even to the level of capturing/matching the whole retina/finger print image will not help : All biometric can be fooled.

Besides the facts confirmed by Mythbuster finger print test, retina scan are not perfect either. And it is not difficult to defeat it when come to "international affair"(AKA Spies) , a contact lens can be crafted to do the job.

Some country storing the biometric info inside passport/identity card for quick data retrieval. That will not help if the wannabe bringing all stuff too fools the equipment that prepared documents from the beginning. You can never stopped an "unknown bad guy" with whatever biometric. That's why some country airport will look for "suspicious behaviour", with drug sniffing dog on duty(may also cause false positive).

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