  An adaptive quantum image encryption method based on wavelet transform is
designed. Since the characteristic of most information is centralized in the
low frequency part after performing the wavelet transform, it reserves the
image low frequency information only, so as to reduce the encryption workload.
Then it encrypts the low frequency information by the random key stream
generated by logistic map, the encryption process is realized by implementing
XOR operation. In the decryption process, it carries out zero filling
operations for high frequency coefficient to recover the decryption images
which are equal to the plain images. At the same time, the relevant quantum
logical circuit is designed. Statistical simulation and theoretical analysis
demonstrate that the proposed quantum image encryption algorithm has higher
security and lower computational complexity. So it is adaptive to the scenes
that need to encrypt a large number of images during network transmission.
