Tamper-evident electric paper is made of two sheets of electric paper
bonded together, the bottom sheet of which includes a pattern. Any attempt
to erase a writing on the top sheet of electric paper results in the
pattern on the bottom sheet of electric paper being erased. Therefore any
tampering by erasure of a writing on the tamper-evident electric paper is
revealed by the absence of a portion of the pattern on the bottom sheet of
electric paper. Single sheet tamper-evident electric paper has a complex
pattern, such as an encryption, printed on a single sheet of electric
paper. Any attempt to erase a writing on the electric paper also erases a
portion of the encryption, thereby providing evidence of tampering.