Patent ID: 7773746
Filing Date: 2010-08-10
Classification: H04L

Abstract:
1. An encryption system comprising an encryption device, which generates an encrypted text by encrypting a plain text according to a predetermined cryptosystem, and a decryption device which generates a decrypted text by decrypting the encrypted text according to the predetermined cryptosystem, wherein said decryption device includes: wherein said encryption device includes an encryption unit operable to generate the encrypted text by encrypting the plain text using the public key and an element r randomly selected from the ring R, wherein all of elements in an N-dimensional array of the N-dimensional arrays indicate 0 or 1, the N-dimensional array being the element f, g or r, or the plain text, wherein the ideal p and the ideal q are relatively prime, wherein the ideal q is expressed by q=(2^k)*R, where the ideal q is a set of multiples of (2^k) in the ring R, 2^k denotes a result of 1 multiplied k times by 2, and * denotes a multiplication of the ring R, wherein said key generation unit is further operable to wherein the ideal p is expressed by p=pg*R with respect to an element pg in the ring R, where the ideal p is a set of multiples of the element pg in the ring R, whereas the ideal q is expressed by q=qg*R with respect to an element qg in the ring R, where the ideal q is a set of multiples of the element qg in the ring R, and wherein the dimension N, the elements pg and qg, and the non-negative integers df, dg and d are derived based on a conditional expression indicating a condition for preventing an occurrence of decryption failure.