GOST, known as GOST-28147-89, was standardized as the Russian encryption standard in 1989. It is a lightweight-friendly cipher and suitable for the resource-constrained environments. However, due to the simplicity of GOST’s key schedule, it encountered reflection attack and fixed point attack. In order to resist such attacks, the designers of GOST proposed a modification of GOST, namely, 2-GOST. This new version changes the order of subkeys in the key schedule and uses concrete S-boxes in round function. But regarding single-key attacks on full-round 2-GOST, Ashur et al. proposed a reflection attack with data of on a weak-key class of size , as well as the fixed point attack and impossible reflection attack with data of for all possible keys. Note that the attacks applicable for all possible keys need the entire plaintext space. In other words, these are codebook attacks. In this paper, we propose single-key attacks on 2-GOST with only about data instead of codebook. Firstly, we apply 2-dimensional meet-in-the-middle attack combined with splice-cut technique on full-round 2-GOST. This attack is applicable for all possible keys, and its data complexity reduces from previous to . Besides that, we apply splice-cut meet-in-the-middle attack on 31-round 2-GOST with only data of . In this attack, we only need 8 bytes of memory, which is negligible.

中文翻译：

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改进了2-GOST的单键攻击

GOST，即GOST-28147-89，在1989年被标准化为俄罗斯加密标准。它是一种轻量级友好的密码，适用于资源受限的环境。但是，由于GOST密钥计划的简单性，它遇到了反射攻击和定点攻击。为了抵抗这种攻击，GOST的设计者提出了对GOST的修改，即2-GOST。此新版本更改了密钥计划中子密钥的顺序，并在回合功能中使用了具体的S盒。但是关于全回合2-GOST的单键攻击，Ashur等人。提出了的数据的反射攻击的弱密钥班级规模，以及固定的攻击点，也不可能反射攻击与数据所有可能的键。请注意，适用于所有可能密钥的攻击需要整个纯文本空间。换句话说，这些是密码本攻击。在本文中，我们提出了对2-GOST的单密钥攻击，该攻击仅涉及数据而不是密码本。首先，我们将二维中间相遇攻击与剪接技术相结合，应用于全程2-GOST。此攻击适用于所有可能的密钥，其数据复杂性从以前的降低到。除此之外，我们仅对数据进行了针对第31轮2-GOST的剪接式中间相遇攻击。在这种攻击中，我们只需要8个字节的内存，这可以忽略不计。