Weak Keys for IDEA
نویسندگان
چکیده
Large classes of weak keys have been found for the block cipher algorithm IDEA, previously known as IPES [2]. IDEA has a 128bit key and encrypts blocks of 64 bits. For a class of 2 keys IDEA exhibits a linear factor. For a certain class of 2 keys the cipher has a global characteristic with probability 1. For another class of 2 keys only two encryptions and solving a set of 16 nonlinear boolean equations with 12 variables is sufficient to test if the used key belongs to this class. If it does, its particular value can be calculated efficiently. It is shown that the problem of weak keys can be eliminated by slightly modifying the key schedule of IDEA.
منابع مشابه
Differential-Linear Weak Key Classes of IDEA
Large weak key classes of IDEA are found for which membership is tested with a differential-linear test while encrypting with a single key. In particular, one in every 2'' keys for 8.5-round IDEA is weak. A related-key differential-linear attack on 4-round IDEA is presented which is successful for all keys. Large weak key classes are found for 4.5to 6.5-round and 8-round IDEA for which membersh...
متن کاملNew Weak-Key Classes of IDEA
This paper presents a large collection of new weak-key classes for the IDEA cipher. The classes presented in this paper contain 2−2 weak keys (as compared with 2 differential weak keys presented by Daemen at CRYPTO’93 and 2 differential-linear weak-keys presented by Hawkes at EUROCRYPT’98). The novelty of our approach is in the use of boomerang distinguishers for the weak-key class membership t...
متن کاملA Note on Weak Keys of PES, IDEA, and Some Extended Variants
This paper presents an analysis of the PES cipher in a similar setting as done by Daemen et al. at Crypto’93 for IDEA. The following results were obtained for 8.5 round PES: a linear weak-key class of size 2; two distinct differential weak-key classes of size 2; two differentiallinear weak-key classes of size 2. For 17-round PES (double-PES): a linear weak-key class of size 2, and a differentia...
متن کاملGenetic Symmetric Key Generation for IDEA
Cryptography aims at transmitting secure data over an unsecure network in coded version so that only the intended recipient can analyze it. Communication through messages, emails, or various other modes requires high security so as to maintain the confidentiality of the content. This paper deals with IDEA’s shortcoming of generating weak keys. If these keys are used for encryption and decryptio...
متن کامل