Authentication Frequency and Challenge Type Based on Environmental and Physiological Properties

A system comprising:

• a processor;
• and
• a computer-readable storage medium storing instructions which, when executed by the processor, cause the processor to perform operations comprising:
• presenting a first authentication challenge on a device at a first time;
• obtaining a measurement of a physiological property associated with a user of the device at a second time later than the first time;
• and
• presenting a second authentication challenge on the device at a third time later than the second time, wherein a time interval between the first time and the second time is based on the measurement.

A computer-readable storage device storing instructions which, when executed by a processor, cause the processor to perform operations comprising:

• presenting a first authentication challenge on a device at a first time;
• obtaining a measurement of an environmental property associated with the device, at a second time later than the first time;
• and
• presenting a second authentication challenge on the device at a third time later than the second time, wherein a time interval between the first time and the second time is based on the measurement.