A cryptographic key is generated using biometric data and a hierarchy of biometric descriptors. The hierarchy of biometric descriptors includes multiple levels, wherein a biometric descriptor at a first level is associated with a subset of the biometric descriptors at the next lower level. To generate a cryptographic key, biometric data is collected and compared to the biometric descriptors at the first level of the hierarchy. One of the biometric descriptors is selected at the first level, and a first key component is generated based on the first selected biometric descriptor. The biometric data is then compared to the subset of biometric descriptors at the second level of the hierarchy associated with the first selected biometric descriptor. This process of selecting a biometric descriptor and generating a key component continues for each level of the hierarchy. The key components are then used to generate a cryptographic key.