A tangible, non-transitory, machine-readable medium storing instructions that when executed by one or more computing devices effectuate operations, comprising:
- receiving, with a first computing device, a request to authenticate a user of the first computing device;
- obtaining, with the first computing device, an unstructured-data authentication input, the unstructured-data authentication input being a signature drawn by a user of the first computing device or other biometric measurement of the user of the first computing device;
- extracting, with the first computing device, from a plurality of different portions of the unstructured-data authentication input, a plurality of features exhibited by respective portions of the unstructured-data authentication input, the extracted features forming a structured-data representation of the authentication input;
- determining, with the first computing device, a first instance of a value that deterministically varies between authentication attempts;
- and
- determining, with the first computing device, a first encrypted value based on both the structured-data representation of the authentication input and the first instance of the value that deterministically varies;
- sending, with the first computing device, the first encrypted value to a second computing device,
- wherein the first encrypted value is sufficient to authenticate the user based on the signature or other biometric measurement without sending a reusable copy of the signature or other biometric measurement during authentication;
- receiving, with the second computing device, the encrypted value;
- obtaining, with the second computing device, in unencrypted form, a second instance of the value that deterministically varies;
- accessing, with the second computing device, a previous structured-data representation based on a user identifier, the previous structured-data representation having features extracted from a previous signature or other biometric measurement of the user;
- determining, with the second computing device, a second encrypted value based on both the second instance of the value that deterministically varies and at least some of the previous structured-data representation;
- and
- comparing, with a computing device other than the first computing device, the second encrypted value and the first encrypted value to authenticate the user.