Conflict of interest

QIFM values is around 91, which is considered that the extracted text have

C-NOT gates. The complexity of embedding circuit is:

¼ 320n � 64 þ 4608 ¼ 320n þ 4544

QIFM values of the extracted text and their original secret text.

Advances in Quantum Communication and Information

¼ 320n � 64 þ 768 ¼ 320n þ 704

The circuit complexity depends on the number of the elementary quantum gates. Thus, we take C-NOT gate as the basic unit. For our proposed scheme, the circuit complexity consists of two parts: embedding and extracting. In embedding part, the scrambling circuit complexity is 7. The embedding circuit is composed of eight QE circuits with three control qubits and eight embedding blocks with one control qubit. As the literature [42] pointed out, only 4ð Þ k � 8 2-C-NOT gates are needed to construct one k-C-NOT gate. Again, one SWAP gate is equivalent to three

Stego image QIFM values of two texts

Stego-Lena 91.0899 Stego-airplane 91.5049 Stego-cameraman 91.6392 Stego-pepper 91.1998

8 � ½4n � ð Þþ 4 � 4 � 8 ð Þ 4 � 2n � 8 � þ 8 � ½ � 16 � 3 � ð Þ 4 � 5 � 8

8 � ½4n � ð Þþ 4 � 4 � 8 ð Þ 4 � 2n � 8 � þ 8 � ½ � 8 � ð Þ 4 � 5 � 8

Therefore, the circuit complexity of the proposed scheme is 640 ð Þ n þ 5262 ,

This chapter proposes a new grayscale image steganography scheme which using NEQR representation to represent a 2<sup>n</sup> � <sup>2</sup><sup>n</sup> cover image and presenting an improved representation of quantum text to store secret text with 2<sup>n</sup>�1þn�<sup>2</sup> symbols. The Gray code of the highest three qubits of the gray value of the cover image is used as a judgment condition in embedded procedure. The acquisition

of secret text is a process of extracting and reorganizing and inversely scrambling eight bit-planes, and it is worth mentioning that the process is absolutely blind. In addition, simulation results about the visibility quality and robustness of the proposed scheme are provided. And the circuit complexity is

blocks with one control qubit. The complexity of extracting circuit is:

In extracting part, the complexity of descrambling circuit is 7, and the extracting circuit is consist of eight QE circuits with three control qubits and eight extracting

(21)

(22)

a good fidelity.

Table 2.

i.e., Oð Þ n .

6. Conclusion

analyzed at last.

26

5.3 Circuit complexity

The authors declare no conflict of interest.
