A new convertible designated confirmer signature based on elliptic curve is presented.The new scheme not only can resist all forgery attacks

but also has the properties of convertibility and retraction.The convertibility is that the designated confirmer signature can be converted into general signature if needed.The retraction is that the original signer can retract the right of the designated confirmer's signature verification if needed.The new scheme is constructed based on elliptic curve

therefore the scheme is possessed of the merits of higher security

higher efficiency

smaller key

and very simplicity etc.