1. A biometric authentication system comprising: a biometric enrollment system configured to determine, for each person in a group of multiple, different people, a similarity score that represents a similarity between a biometric image of at least a portion of the corresponding person from the group of multiple, different people and a reference image and sort biometric data that includes all of the determined similarity scores using the determined similarity scores, wherein the reference image is used in determining all of the similarity scores included in the biometric data; a data storage system configured to maintain, for the group of multiple, different people, biometric data that includes all of the sorted similarity scores; and a biometric verification system that includes at least one processor, the biometric verification system being configured to: access a particular biometric image of at least a portion of a particular person; access the reference image used in computing all of the similarity scores maintained in the data storage system; compute a particular similarity score that represents similarity between the accessed particular biometric image and the reference image; search, using the computed particular similarity score, the sorted similarity scores included in the biometric data for the group of multiple, different people; determine whether the data storage system includes data for the particular person in the biometric data based on the search of the sorted similarity scores included in the biometric data using the computed particular similarity score; and output a result based on the determination of whether the data storage system includes data for the particular person in the biometric data.