A Dynamic Threshold Proxy Digital Signature Scheme by using RSA Cryptography for Multimedia Authentication

paper we propose a threshold digital signature scheme by using RSA cryptography to authenticate multimedia content. Multimedia authentication deals with genuineness of the structure and content of the multimedia such as text, image, audio, video etc. The proposed scheme uses an efficient key distribution scenario where, the private key of the group is distributed as unique shares among the group members. The shares are calculated and distributed based on the ID of the group members by using efficient Shamir's secret sharing scheme. For convenience the group members can be dynamically added or deleted. The private key of the group is updated if there is any violation in the threshold limit t due to variation of the number of group members in the group. The signer in the group will be able to reconstruct the private key from t or more shares given by the group members to sign the multimedia document. In this scheme any t or more group members can cooperatively generate the group signature where t-1 or fewer cannot do it. This scheme is also secure against conspiracy attack.