Galaxy: A Family of Stream-Cipher-Based Space-Hard Ciphers
Galaxy: A Family of Stream-Cipher-Based Space-Hard Ciphers
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Galaxy：一系列基于流密码的太空硬密码
DOI：
10.1007/978-3-030-55304-3_8
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Isobe Takanori
中科院分区：
文献类型：
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作者：
Koike Yuji;Sakamoto Kosei;Hayashi Takuya;Isobe Takanori
白盒密码学旨在确保密码算法的安全性，以对抗那些对其实施环境具有无限访问权限的对手。在ACM CCS 2015上，Bogdanov和Isobe提出了一个称为空间硬度的安全概念，并在白盒环境中提出了一个名为SPACE的安全块密码。SPACE是一种基于表的密码原语，其表包括分组密码（如AES）的输入对和相应的输出。与SPACE一致，提出了其他白盒密码方案，并提供了足够的安全性。然而，在加密和表生成的性能方面仍有改进的空间。在本文中，我们提出了一个新的家庭的白盒密码原语称为银河，以提高性能的加密和表生成。Galaxy使用流密码而不是块密码来生成表。将Galaxy在白盒环境下抵抗密钥提取攻击的安全性归结为流密码在黑盒环境下的密钥提取问题。此外，我们利用第二类广义Feistel网络的最佳洗牌层的银河算法，以提高加密性能。Type-2广义Feistel网络实现了Galaxy算法中的并行查表。结果，我们成功地将加密速度提高了1.3-15倍。此外，当我们使用chacha为其他现有的基于分组密码的白盒方案的Galaxy和AES的表生成时，我们可以比其他现有的白盒方案快1.5-10倍地创建Galaxy的表。
Whitebox cryptography seeks to ensure the security of cryptographic algorithms against adversaries who have unlimited access to the environments for their implementation. At ACM CCS 2015, Bogdanov and Isobe proposed a security notion called space hardness and a secure block cipher named SPACE in the whitebox setting. SPACE is a table-based cryptographic primitive whose table comprises the pairs of inputs to a block cipher such as AES and the corresponding outputs. In line with SPACE, other whitebox cryptographic schemes were proposed and offer sufficient security as SPACE does. However, there is still room for improvement in the performance of their encryption and table generation. In this paper, we propose a new family of whitebox cryptographic primitives called Galaxy to enhance the performance of the encryption and table generation. Galaxy employs a stream cipher to generate the table instead of a block cipher. The security of Galaxy against key-extraction attacks in the whitebox setting is reduced to the key-extraction problem for the stream cipher in the blackbox setting. Additionally, we utilize type-2 generalized Feistel network with optimal shuffle layers for the algorithm of Galaxy to improve the encryption performance. Type-2 generalized Feistel network enables parallel table lookups in the algorithm of Galaxy. As a result, we successfully increase the speed of encryption by 1.3–15 times. Besides, when we use chacha for table generation of Galaxy and AES for other existing block-cipher-based whitebox schemes, we can create the table of Galaxy 1.5–10 times faster than that of other existing whitebox schemes.