| 摘要 |
A secret sharing system and a storage medium where each of the n shareholders P1 to Pn holds a (n, n) share di (0<=i<=n), turns the share di into t(r+1) partial random numbers Sj of the (t, n) type, shares r+1 partial random numbers Sj to the respective shareholders P1 to Pn on the basis of a t-ary representation (value k at the t<j>-th digit, 0<=k<=t-1, 0<=j<=r) of the identification number z of each of the shareholders Pi, and puts together the shared partial random numbers for each digit t<j >in the t-ary representation to obtain r+1 shares dj,k. Then, the user unit U selects t shareholders TZ and transmits encrypted data C to the selected t shareholders TZ. The t shareholders Tz perform an operation on the encrypted data C on the basis of the share dj,k to obtain partial outputs XZ and return the partial outputs XZ to the user unit U. Then, the user unit U combines the t partial outputs XZ to obtain the result of decryption.
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