| 摘要 |
This decryption condition addition device (300) acquires an original ciphertext ctS, for which a secret sharing matrix M has been set as information stipulating a decryption condition, and an additional access structure S+, which is a restriction condition that restricts the decryption condition for the original ciphertext ctS. The decryption condition addition device (300) adds, to the secret sharing matrix M that has been set for the original ciphertext ctS, a row and column indicated by the additional access structure S+, and generates an updated ciphertext ctS' in which the decryption condition for the original ciphertext ctS is restricted. |
