تجزیه و تحلیل عملکرد مبتنی بر FPGA از رمزهای جریان ZUC، Snow3g، دانه V1، V2 میکی، Trivium و E0

In this paper, the hardware implementations of six representative stream ciphers are compared in terms of performance, consumed area and the throughput-to-area ratio. The stream ciphers used for the comparison are ZUC, Snow3g, Grain V1, Mickey V2, Trivium and E0. ZUC, Snow3g and E0 have been used for the security part of well known standards, especially wireless communication protocols. In addition, Grain V1, Mickey V2 and Trivium are currently selected as the final portfolio of stream ciphers for Profile 2 (Hardware) by the eStream project. The designs were implemented by using VHDL language and for the hardware implementations a FPGA device was used. The highest throughput has been achieved by Snow3g with 3330 Mbps at 104 MHz and the lowest throughput has been achieved by E0 with 187 Mbps at 187 MHz. Also, the most efficient cipher for hardware implementation in terms of throughput-to-area ratio is Mickey V2 cipher while the worst cipher for hardware implementation is Grain V1.

In communication systems cryptography is used in order to provide secrecy, authentication and integrity [1]. To achieve these services all the communication protocols use cryptographic algorithms (ciphers). There are two major categories of cryptographic algorithms. The algorithms which use secret keys (also known as symmetric algorithms) and the algorithms which use public keys (also known as asymmetric algorithms). In asymmetric cryptography the sender uses a public known key to encrypt the message. Then, the receiver uses his/her own secret key to decrypt the cipher text in order to read the initial message. In symmetric key cryptography, both sides have previously agreed on the same private secret key which will be used to protect their communication. Usually, for exchanging of this private secret key the asymmetric cryptography is used. Symmetric algorithms can also be categorized into block ciphers and stream ciphers algorithms [2]. Block ciphers manage the input data in form of N-bit blocks and then with the information of secret key generate N-bit blocks of encrypted or decrypted data. For the generation of ciphertext/plaintext sophisticated mathematical equations, permutations and some other techniques depend on the algorithm are used. On the other hand, stream ciphers (also called keystream generators) contain internal states and typically operate serially by generating a stream of pseudo-random key bits, the keystream. The keystream is then bitwise XORed with the data to encrypt/decrypt. One advantage of stream ciphers is that they do not suffer from the error propagation as it happens in block ciphers [3]. This is the result of the independent bit encryption and decryption. Another advantage is that they could be implemented easier in both software and hardware compared to block ciphers. So, stream ciphers have been the choice for several telecommunication protocols such as Global System for Mobile (GSM) [4], Long Term Evolution (LTE) [5] and Bluetooth [6]. Six stream ciphers were selected for the hardware comparison analysis in this paper. Three of them (ZUC, Snow3g and E0) have been used for the security part of well known protocols. Specifically, ZUC algorithm is part of the 128-EEA3 and the 128-EIA3 protocols used for confidentiality and integrity, respectively, in the wireless transmissions in LTE. This set of protocols has been developed by 3GPP [7] and GSM association. Snow3g algorithm is part of two sets of security protocols with the same purpose, confidentiality and integrity. The first set consists of the 128-EEA1 and the 128-EIA1, which have been developed by SAGE/ETSI [8] for the LTE standard. The second set consists of the UEA2 and the UIA2, which also have been developed by SAGE/ETSI for Universal Mobile Telecommunication System (UMTS) networks [9]. Finally, the E0 is the security algorithm used in Bluetooth protocol for packet encryption and granting confidentiality. The other three algorithms (Grain V1, Mickey V2 and Trivium) have been selected for the eStream portfolio for Profile 2 (Hardware) by the eStream project. The eStream portfolio provides secure cipher for usage in a wide range of applications. The algorithm implementations could be software or hardware oriented. However, because of the continuously growing requirements for high speed solutions the hardware implementations are more efficient. To achieve higher levels of secure communication the algorithms tend to be more sophisticated. This means that those algorithms have also higher demands for processing power. With software solutions this could cause bottleneck problems in data flow in high speed networks. Also, in these implementations the full bandwidth utilization could not be achieved. In this, paper the hardware implementations of the above six stream ciphers are presented. The performance metrics are the throughput, the area consumption and the efficiency for the hardware implementation in terms of throughput-to-area ratio. These metrics are basic for comparisons and analysis in hardware. For the implementation an FPGA device was used. This solution is a highly promising alternative because superior performances could be achieved. For design’s implementations the hardware description language VHDL was used. The software tools used for synthesize, simulation, measuring throughput and area consumption are ISE tool and Modelsim. The rest of the paper is organized as follows. In the next section the algorithms, their basic operations and technical characteristics are presented. The hardware implementations are given in detail in Section 3. For all the designs a description about their interfaces and the components are given. In Section 4 implementation results for the selected FPGA device and the experimental results are illustrated and analyzed. Finally, Section 5 concludes this paper.

In this paper, six well known stream ciphers are implemented in hardware and compared in terms of time performance, area consumption and throughput-to-area ratio. The highest throughput is achieved by Snow3g with 3330 Mbps. However, this causes high hardware resources of the design, which results to low throughput-to-area ratio. The same holds also for ZUC algorithm that achieves a high throughput but consumes high levels of hardware resources. The highest operation frequency is achieved by Trivium implementation with average hardware demands. The cipher which failed to present some remarkable results is Grain V2, which has the lowest value in terms of throughput. In terms of area consumption the lowest value is achieved by Mickey V2 with 98 logic slices. This lead to the best throughput-to-area ratio with 2.554 Mbps/#Slice compared to the rest of ciphers.