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Hitachi Crypto Technology

What is HIME(R)?

  • HIME(R) is the public-key cryptosystem and based on a modular squaring (Rabin's public-key encryption scheme) over Z_N, where N=p^dq (p and q are prime integers, and d>1), and utilizes the fast calculation method for decryption. With HIME(R), security is additionally enhanced by the OAEP converting method.
  • HIME(R) has the following exceptional features:
    1. It is proven to be semantically secure against an adaptive chosen-ciphertext attack(IND-CCA2) in the random oracle model under the factoring assumption of N.
    2. It has a very fast encryption speed.
    3. The decryption speed (1536 bits) is about two-and-a-half times faster than that of RSA-OAEP (1024 bits).
    4. The plaintext space is sufficiently large.
    5. The amount of computation for the encryption and decryption increases only slightly compared with previous schemes, even if the size of N increases in the future.