| CPC H04L 9/0618 (2013.01) [H04L 9/0869 (2013.01)] | 22 Claims |

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1. An authentication system transmitting a ciphertext of authentication information from an authenticatee apparatus to an authenticator apparatus using homomorphic encryption with a public key encryption scheme, wherein
the authenticator apparatus issues a first random number to the authenticatee apparatus,
the authenticatee apparatus generates a second random number and transmits to the authenticator apparatus a first element generated with a public key using the first and the second random numbers and a second element generated with a public key using the second random number, and
the authenticator apparatus modifies the second element using the first random number to obtain a ciphertext of the authentication information.
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