We show how to construct a practical secure signature padding scheme for arbitrarily long messages from a secure signature padding scheme for fixed-length messages. This new construction is based on a one-way compression function respecting the division intractability assumption. By practical, we mean that our scheme can be instantiated using dedicated compression functions and without chaining...

The South American knifefish (Apteronotus leptorhynchus), or brown ghost, produces a high-frequency (600-1000 Hz) sinusoidal electric organ discharge (EOD) with males discharging at higher frequencies than females. In addition, each fish has a unique EOD frequency within the frequency range of its gender. The electromotor circuit responsible for EOD production consists of a medullary pacemaker ...