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With the rapid evolution of data exchange in network environments, information security has been the most important process for data storage and communication. In order to provide such information security, the confidentiality, data integrity, and data origin authentication must be verified based on cryptographic encryption algorithms. This paper presents a new emerging trend of modern symmetric encryption algorithm by development of the advanced encryption standard (AES) algorithm. The new development focuses on the integration between Quantum Key Distribution (QKD) and an enhanced version of AES. A new quantum symmetric encryption algorithm, which is abbreviated as Quantum-AES (QAES), is the output of such integration. QAES depends on generation of dynamic quantum S-Boxes (DQS-Boxes) based quantum cipher key, instead of the ordinary used static S-Boxes. Furthermore, QAES exploits the specific selected secret key generated from the QKD cipher using two different modes (online and off-line).

Recently, two distinct ciphers for cryptography processes are defined, symmetric and asymmetric cipher [

Asymmetric encryption techniques are about 1000 times slower than symmetric encryption which makes it impractical when trying to encrypt large amounts of data [

Generally, symmetric technique divided into two broad categories: stream cipher and block cipher [

Moreover, a block cipher transforms 64; 128; 192 or 256-bit to string of the same length under the control of secret key [

This paper discusses the AES block cipher symmetric algorithm. Scalability, easy to implement and resistance against attacks are well-known features for such algorithm [

Unfortunately, most of modern encryption algorithms rely entirely on a complex mathematics computation in the key generation and distribution and management. So, it is vulnerable to quantum attack and the man-in- the-middle attack. Quantum computation especially QKD is the first solution to these problems.

QKD is an important practical application of quantum computation. It is based on laws of physics rather than computation complexity of mathematical problems. It can generate security keys between two communications and guarantee security of sensitive data (for more details see [

This paper discusses and analyzes the structure of Substitutions boxes (S-boxes) in the traditional AES. Moreover, based on a quantum cipher key, a dynamic quantum S-Boxes (DQS-Boxes) is generated. Finally, a new version of AES by integration between the enhanced version of AES and QKD in two implemented modes (on-line and off-line) is presented.

The rest of the paper is organized as follows: Section 2 surveys the existing study for AES optimization and cryptanalysis. The developed architecture for QAES and integration modes are given in Section 3. Section 4 explains the inferences obtained from the results and discussion. Section 5 presents the conclusion and future works.

Recently, there are few authors are focused on the enhancing and cryptanalysis of the AES algorithm, because most of AES attacks appeared lately.

For example, Sekar et al. [

Kazys et al. [

Cipher | Nk-words | Nb-words | Nr |
---|---|---|---|

AES-128 | 4 | 4 | 10 |

AES-192 | 6 | 4 | 12 |

AES-256 | 8 | 4 | 14 |

key generation. The authors described in details how to generate random S-Box, key-independent, and ratio of independence for the S-Box elements is computed. The breach of this study was not debating any type of cryptanalysis attacks.

Shaaban et al. [

However, contrast to above studies, the first cryptanalysis deployed by Alex B. et al. [

S. Hadi et al. [^{2}, the fastest attack of all the previous ones from time and pre-computation complexities points of views. This attack is the first related key impossible differential attack which is applied to 7-round AES-128. A fundamental point to construct such attack is using a special property of Mix Column operation of AES.

Other studies [

Finally, we can conclude that many studies have attempted to enhance the strength and efficiency of AES algorithm without changed in a core of AES structure. In other hand, not fully rounds hacked by the attackers, the best states reached to seven rounds (out of ten) for AES-128, and ten (out of 12 or 14) rounds for AES-192 and AES-256.

This section illustrates the QAES development steps based on two different modes (on-line and off-line modes). The main machine utilizes the Core i5 (4.8 GHz) with 8 GB of RAM with 500 GB-HDD, while, the simulator is programmed using Visual Studio Ultimate 2012 (VC#).

The QAES developed system incorporates both the QKD and an enhanced version of the AES in order to provide an unconditional security level [

The DQS-boxes enjoy the dynamic mechanism, in which the contents of each S-Box changes consequently in each round with the change of the key generation. Such dynamic mechanism aids in solving the mechanism problems associated with the traditional S-Boxes. Avoiding the off-line analysis attack, overcoming the DS-Box [

Since the unconditional security depends on the Heisenberg uncertainty principle (core feature in quantum theory) [

The integration between the enhanced AES and the QKD uses two different modes the online and the off-line is explained in this section.

During the negotiation between the two parties (master, slave), as shown in

The on-line mode follows the following steps:

・ The quantum secret key is generated over the quantum channel using BB84 protocol.

・ The master and slave parties check the online compatibility for the generated secret key.

・ The master and the slave choose the appropriate key length (128; 192; 256 bits) through the classical channels in order to perform the encryption/decryption process.

・ The two parts deploy the selected final quantum secret key (q_{k}) to the symmetric encryption algorithm (AES).

・ The system automatically creates the DQS-Box based on the secret key generation with length 256-bits.

・ Encrypt the first block input file (P1-128 bits) by the AES stages―using qk_{1} which generate by QKD round1.

・ Finally, Encrypt final block input file by the AES stages―using qk_{n} which generate by QKD round_{n}, where

・ The decryption process start with the end of the encryption process (inverse methodology).

Due to the key availability (KA) associated with QKDs [

Finally, this mode can be used with any type of encryption modes such as cipher feedback (CFB) mode, output feedback (OFB) mode, and the counter (CTR) mode.

Despite of many positive criteria for QKD such as KA, key distribution and management, they depend on exchanging photons between parties over limited distances (314 km) [

As shown in

The off-line mode follows the following steps:

・ Generate the random qubits from QKD, these qubits act as secret key (k).

・ Based on this K, the system creates DQS-Box.

・ Using classical AES-key scheduler, the sub-keys for each AES-round are generated.

・ Finally, steps (4, 5, 6, 7 and 8) in the on-line mode are typically performed.

Due to the results of the random tests implementation mention in [

In this section the ratio of independency for DQS-Box and the time of encryption process have been implemented, measured and analyzed based QAES. After then, the results are compared when the same processes are implemented based classical AES.

The ratio of independent mainly depends on Equations (1)-(4), these equations are used for the classical S-boxes correlation and independency computations [

where CORR is a ratio of correlations.

For example, regarding to the simulation environment for QKD, two DQS-Boxes are generated with 256 bits (matrix 16 × 16). According to Equations (1)-(4), the ratio of correlation functions and independence between DQS-Box1 and DQS-Box2 are shown in

As shown in the above figures, the ratio of correlation (CORR) coefficient is 6.606%, while the ratio of independence is 93.359%. Exactly, the ratio of independent ranging between (72.78% - 100%) for each corresponding row between two DQS-Boxes, [for more details see Appendix], which indicates that the QAES provides a highly unrelated Box that led to a more secured connection. Moreover, the DQS-Box generation process enjoys the advantage that the intermediate generation done during the encryption/decryption process which avoids the offline analysis attack associated with the S-Box.

In the following analysis, both the AES and QAES algorithms have been implemented using several input files

sizes: 500 kb, 1000 kb, 1500 kb, 2000 kb, and 3500 kb.

Comparing the QAES with traditional AES encryption algorithms reflects a higher security level. However, as shown in Equation (5), and _{QKG}) and time required for the encryption/decryption process T(Enc(P)).

where T_{qenc} = Total encryption based QAES and P_{n} = plain file.

As showed in

Generally, we can conclude that the QAES is a little bit slower than the AES. For example, according to Figures 8-10, and Equation (5), the encryption time of AES-128 bits is 0.101 ms for file size 3500 kb. While, QAES-128 bits takes 0.23 ms for key generation has length 200-qubits and 0.100 ms for file encryption. So, the total time for QAES-128 is 0.123 ms and 0.135 ms for QAES-192.

Finally, since the QAES follows the same architecture of the AES, the input file size has always changed during encryption process and the details of the processed file remain unchangeable.

In this paper a developed version of AES algorithm, annotated as QAES, based on quantum encryption mechanism and dynamically S-Boxes have been introduced, implemented and discussed. The paper shows that the QAES development and design do not contradict the security of the AES algorithm, since all the mathematical criteria remain unchanged. The QAES symmetric encryption algorithm has been revealed depending on the integration between the AES and the QKD using two different modes, the On-line and the Off-line. The experimental results and the analysis show that the QAES produces more complicated un-breakable keys, hard to be predicted by attackers than the keys generated by the AES. However, the speed of encryption of the QAES is tiny higher (0.409 seconds) than that using the AES. The strength of the QAES lies in its ability of generating a high ratio of independence between DQS-Boxes, see Appendix; this ratio aids in achieving a more secured environment against most types of cryptanalysis attacks.

In the future, in order to assure the strength of the QAES, the algebraic and quantum attacks are going to be implemented, and the results are going to be analyzed.

Omer K.Jasim,SafiaAbbas,El-Sayed M.Horbaty,Abdel-Badeeh M.Salem, (2015) Evolution of an Emerging Symmetric Quantum Cryptographic Algorithm. Journal of Information Security,06,82-91. doi: 10.4236/jis.2015.62009

This appendix contains the two randomly DQS-boxes, and relations between them.