A protoype algorithm: PINVOX ("Personal
Identification Number by Voice") for on-line certification is
introduced to guarantee that scholars have followed, i.e.,
listened and watched, a complete recorded lecture with the
option of earning a certificate or diploma of completion
after remotely attending courses. It is based on the injection
of unique, randomly selected and pre-recorded integer
numbers (or single letters or words) within the audio trace
of a video stream at places where silence is automatically
detected. The certificate of completion or "virtual
attendance" is generated on-the-fly after the successful
identification of the embedded PINVOX code by a video
viewer student