The block cipher CRYPTON has been proposed as a candidate algorithm for the Advanced Encryption Standard (AES). To fix some minor weakness in the key schedule and to remove some undesirable properties in S-boxes, we made some changes to the AES proposal, i.e., in the S-box construction and key scheduling. This paper presents the revised version of CRYPTON and its preliminary analysis. L. Knudsen (Ed.): FSE'99Byte Transposition τ It simply moves the byte at the (i, j)-th position to the (j,

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... position, i.e., B = τ (A) ⇔ b ij = a ji . Note that τ −1 = τ . Key Xoring σ For a round key Round Transformation ρ One round of CRYPTON consists of applying γ, π, τ and σ in sequence to the 4 × 4 data array. More specifically, the odd and even round functions are defined (for round key K) by ρ oK = σ K • τ • π o • γ o for odd rounds, ρ eK = σ K • τ • π e • γ e for even rounds.