A Timestamped Signature Scheme with Message Recovery

We propose a timestamped signature scheme which can be verified universally using signer's public parameters. A trusted third party, the Time-Stamping System provides timestamp to a signature without even knowing the content of the document. The proposed scheme can withstand active attacks, such as forgery attack and chosen cipher text attack. It also provides the message recovery feature, i.e., from the time stamped signature, the message can be recovered by the receiver. Hence, the message need not be sent with the signature. The suggested scheme do not require any hash function and there by reduces the verification cost as compared to existing schemes at the expense of marginal increase in signature generation cost. Further, the scheme is more secured as its security lies in solving three computationally hard assumptions.