Controlled Delegation in e-cheques Using Proxy Signatures

A proxy signature scheme allows one user to delegate his/her signing capability to another user called a proxy signer in such a way that the latter can sign messages on behalf of the the former. After verification the verifier is convinced of the original signer's agreement on the signed message. We have come up with a scheme to control delegation of financial power to a proxy signer. The scheme satisfies the basic requirements of a secure proxy signature scheme. Using our scheme the proxy signer will be able to submit an e-cheque for only the amount he is entitled to by the original signer. Any cheating by the original signer or the proxy signer is identified by the verifier i.e. the bank. We have considered Forgery by the original signer, Impersonating and framing attack to prove the security of our scheme. Any discrete log based signature scheme can be used to sign the messages. Here we use the digital signature algorithm (DSA).