A digital video camera includes an image sensor capable of producing a
frame of video data representing an image viewed by the sensor, an image
memory for storing video data such as previously recorded frame data in a
video frame location of the image memory, a read circuit for fetching the
previously recorded frame data, an encryption circuit having an
encryption key input connected to receive the previously recorded frame
data from the read circuit as an encryption key, an un-encrypted data
input connected to receive the frame of video data from the image sensor
and an encrypted data output port, and a write circuit for writing a
frame of encrypted video data received from the encrypted data output
port of the encryption circuit to the memory and overwriting the video
frame location storing the previously recorded frame data.